SBO Handbook

Sommers-Bausch Observatory Handbook
Tenth Edition
DEPARTMENT OF ASTROPHYSICAL AND PLANETARY SCIENCES
University of Colorado at Boulder


Comments from the Manager
After twenty years of teaching TA workshop and trying to include everything that needs to be said in the short period of time alloted for training, Keith Gleason (former observatory manager) decided to augment the learning experience with this short and very useful training manual.
Much of the material has simply been assimilated from a number of previously written sources - principally for the ASTR 1010 and ASTR 1030 lab manuals, but also from miscellaneous handouts that have been generated over the years. It is always a work in progress, and by the time this booklet is published, there will likely be some changes that will have made some portions obsolete. But that's not a bad thing ... change means progress, and change is the only thing that is absolutely certain in the field of astronomy.
Our thanks to the late Dr. Roy Garstang, the CU Archives, and the High Altitude Observatory for much of the information and photographs of the early years of SBO. Thanks also to the Denver Library for information and photos of Elmer Sommers, Ed Kosmicki of Summit Magazine for the 16-inch night photograph, and Casey Cass of the University of Colorado Photo Department for the image of the new dome slit being installed. Special thanks go to Eric McNeil for the cover picture design.
We’d like to acknowledge the dedication and enthusiastic efforts of the long line of undergraduate Observatory Assistants: Randy Meisner, Andy Danielson, Stephanie Fawcett, Aaron Ceranski, Fabio Mezzalira (now the SBO manager), Kati Eason, Stacey Rugenski, and Eric McNeil. And our appreciation also goes to the departmental Lead TAs who have always been proactive in promoting the educational mission here at Sommers-Bausch: Kelsey Johnson, Cori Krauss, John Weiss, James Roberts, Quyen Hart, Colin Wallace, Jesse Lord, Julia Kamenetzky, and now Amandeep Gill.
We would also like to bid a warm hearted farewell to our former manager Keith Gleason whom has dedicated thirty years of his life to the success and betterment of this wonderful observatory and for all the young lives he has changed on the way.
Fabio Mezzalira


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Table of Contents
Introduction ................................................................................................... 4 History of Sommers­Bausch Observatory..................................................... 6 Room Location Guide.................................................................................... 10 The Resources Room..................................................................................... 12 Recommended Resources List....................................................................... 13 Telephones at SBO......................................................................................... 14 Parking at SBO.............................................................................................. 15 Audio/Video and Computer Connections...................................................... 16 Keys and Access............................................................................................ 18 Safety and Security ....................................................................................... 20 Friday Open House........................................................................................ 22 Frequently Asked Questions
Lost & Found, Emergencies, First Aid, Telescope Probs.................. 23 Shutdown, Malfunction Report, Scope Personal Use........................ 24 Climate Control, Cleaning Up........................................................... 25
Telescopes and Observing Equipment
Permanent Pier­Mounted................................................................... 26 Portable Field Telescopes.................................................................. 27 Ancillaries for Field Trips.................................................................. 28
Appendices
Appendix I: Celestial Coordinates................................................................ 29 Appendix II: Telescopes & Observing.......................................................... 37 Appendix III: Solar Observing at SBO......................................................... 45 Appendix IV: The SBO Catalog of Objects.................................................. 55


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Introduction
Sommers-Bausch Observatory (SBO) on the University of Colorado campus is operated by the Department of Astrophysical and Planetary Sciences (APS) to provide observational experience for CU undergraduate students, and hands-on training in astronomical observations and instrumentation for departmental majors and graduate students. Telescopes include 16, 18, and 24-inch Cassegrain reflectors and a 10-inch aperture heliostat.
The Observatory is used by approximately 2000 undergraduate students each year to view, and in some cases photograph, celestial objects which would otherwise only be seen on the pages of a textbook or discussed in classroom lectures. The three major astronomical telescopes are all controlled via Windows- based Telescope Control Systems (TCS), which are also interfaced to TheSky planetarium-style "click-and- go" pointing software.
The primarily telescope for student visual observing is the DFM Engineering 16-inch telescope. However, newly acquired small eyepiece-mountable spectrograph and CCD camera units (SBIG DSS-7 and ST- 402ME, respectively) are currently being assembled for use on the 16-inch for low-dispersion spectroscopy applications such as stellar classification.
The DFM 18-inch telescope is outfitted with a new large-format thermoelectrically cooled SBIG ST- 2000XCM (CCD) color camera mounted on an 8-inch piggyback telescope, so students can image celestial objects electronically while simultaneously detecting photons with their own eyes at the eyepiece of the 18- inch. The USB format permits rapid download of images, while the integral color mask makes color imaging almost as easy as black and white. A color printer has been added on deck to permit students to take home a hardcopy of their work.
In 2006, the 10.5-inch Bausch lens that was the optical heart of the solar telescope cracked from thermal stress. In the summer of 2007 we received a 10-inch replacement achromat courtesy of Big Bear Solar Observatory and the diligent efforts of Alan Kiplinger. The new lens has a slightly shorter focal length than the old, and necessitated a complete renovation of the optical layout of the heliostat bench. A new protective insulated shelter and remotely-operated aperture control system was completed in the summer of 2010. Finally,in2011,weacquiredanultra-narrow-band(0.5Angstrombandwidth)Hallehydrogen-alpha filter, plus a solar spectroheliograph, from the NOAO labs in Boulder, acquired once again through the hard work of Alan Kiplinger. During the spring of 2012 we successfully broadcast live video images of the partial solar eclipse and Venus transit over the internet using the newly-installed Halle filter on the heliostat.
The 24-inch Boller & Chivens telescope is primarily used for instruction in observational astronomy for our upper-division undergraduate majors and graduate students. When not in use as a training instrument, the telescope is utilized for research projects not feasible with larger telescopes because of time constraints or scheduling limitations. The telescope supports imaging, stellar spectroscopy, and eyepiece observing. Large-format SBIG ST-1001E and Apogee 1109 CCD cameras serve as the primary detectors for imaging and spectroscopy, respectively, with additional CCD cameras used for slit-viewing and autoguiding. Flip- mirror imaging capability permits rapid switching between the two telescope modes. In 2005 the original narrow multiple dome slit doors were replaced with a single wide-slit over-the-top aperture, with additional cooling windows around the dome periphery to improve telescope "seeing”. In the summer of 2010, Fabio Mezzalira converted the old unused 24” Coude Room into a new 24” Control Room, including camera surveillance and monitoring of the telescope. A new ultra-large format SBIG STX-16803 imaging camera has been acquired for the telescope and will be integrated into the system in the Fall 2012.
In addition to the telescope and administrative computer facilities, the Observatory houses COSMOS, one of the most successful and heavily used computer labs on campus. The lab is comprised of a number of Dell and SunRay workstations, a data-reduction server named “scorpius.colorado.edu”, and the main linux server server named "cosmos.colorado.edu".


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Recent improvements include new audio/video equipment and wireless campus internet service now available throughout the building. Work the past several years has emphasized modernizing building's physical appearance: new carpeting for the Observing Deck and Dome Room, new paint for the Dome Room, Astronomy Lab, and Machine Shop, new window coverings and improved lighting for the Astro and Cosmos Labs; and new furniture, optical bench, whiteboards, and overhead projection systems. The new Student Lounge is a place for students to relax, rest during an all-nighter at the telescopes, or for TAs to hold office hours; it boasts new paint, furniture, window coverings, floor coverings, and lighting. New lighting and carpeting are planned for the Astro Lab and Cosmos Lab for the Fall of 2012 thanks to the classroom remodeling program of the College of Arts & Sciences.
SBO Website
http://sbo.colorado.edu
General Contact Information
Observatory Manager: Fabio Mezzalira
Phone Office Phone Cell Fax
E-Mail
303-492-6732
720-329-4482
303-492-2051 [email protected]
Free Open Houses for public viewing through the 16-and 18-inch telescopes are held every Friday evening that school is in session, hosted primarily by APS grad students and faculty. Students, families, groups, and the general public are all welcome.
The Observatory is located on the hill just east of Fiske Planetarium, near the corner of Regent Drive and Kittridge Loop. Look for the medium-sized smooth dome above the crinkled geodesic dome of the planetarium.
SBO Coordinates
Latitude Longitude Altitude
(24-Inch Telescope)
+40° 00' 13.4"
+105° 15' 45.0" 1653 meters ASL
Observatory Director: Seth Hornstein
Phone Duane Phone SBO
Fax E-Mail
303-492-5631 303-492-9105
303-492-2051
[email protected]


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History of Sommers-Bausch Observatory
General Astronomy classes were instituted in the very early years of the University, but not until 1946 did the University possess a significant telescope. In that year the Bausch & Lomb Company gave to the University a 10.5-inch refractor, formerly the property of Carl L. Bausch. The telescope was designed by George Saegmuller, a B&L designer, in 1912 and had stood on the top of a B&L building in Rochester, New York, until about 1941.
The telescope acquisition was negotiated by Dr. Walter Orr
Roberts, acting on behalf of the High Altitude Observatory of
Harvard University. HAO had established the western
hemisphere's first solar coronograph near Fremont Pass near Climax, Colorado, and was looking for new instrumentation to improve their capability. It was soon decided, however, that the B&L telescope would better be suited for sunspot observations from Boulder where the HAO had offices on the CU campus.
Housing for the telescope became possible in 1949 using a bequest of $49,054 from the estate of Mrs. Mayme Sommers in memory of her husband Elmer E. Sommers, a prominent 1920’s Denver oil businessman and avid supporter for Colorado tourism and transportation
development.
The Sommers-Bausch Observatory was built in adapted rural Italian style to match most of the buildings on campus. The new building was dedicated on August 27, 1953, during the 89th meeting of the American Astronomical Society.
The Observatory was first operated under the directorship of Walt Roberts and the management of Dorothy Trotter, and was jointly
owned by the University of Colorado and the High Altitude Observatory of Harvard. Not only was the Observatory used for research and CU classes, but also for free public Friday Night Open Houses, a tradition which has continued uninterrupted for 60 years to the present day.
In 1957 the University formed the Department of Astro- Geophysics (a name chosen to reflect the seminal HAO work in solar physics, space weather, and terrestrial climate effects) and the first graduate courses were taught at SBO. Sunspot observations were made in conjunction with the coronagraph at Climax; the room under the dome was used for radio communication with Climax and the observatory at Sacramento Peak, New Mexico (founded by Roberts and Jack Evans of HAO). Solar flare patrol monitoring was also an ongoing activity at SBO in conjunction with the 1957/58 International Geophysical Year (IGY).


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During the late 1950's, SBO and HAO served as a major center for solar research in the United States, and ultimately led to spin-off facilities such as the National Center for Atmospheric Research, and attracted related institutions such as NOAO and the National Bureau of Standards (now NIST, the National Institute for Standards and Technology).
Teaching and research in astronomy greatly developed in the 1960's, under the acting directorships of various faculty members of the A-G Department (now the Department of Astrophysical and Planetary Sciences), including Dr. Roy Garstang, long-time proponent and supporter of observational astronomy at CU. As the General Astronomy classes steadily increased in size it became obvious that additional facilities were needed to provide training for graduate students before they went to a larger observatory for observing runs.
In 1971 the University received a grant from the Science Development Program of the National Science Foundation to purchase a new telescope, the 24-inch
Cassegrain reflector from the Boller & Chivens Company (a division of Perkin-Elmer Corporation). The telescope was installed in 1973 in the original SBO dome.
The Bausch telescope was dismantled and removed, the mounting being placed in the lobby of the newly-constructed Fiske Planetarium as an exhibit where it remains today. The 10.5" objective glass was extracted and used for the optics of a solar telescope installed on the roof of the Duane Physics Building, and operated under the direction of Dr. Don Billings, a member of the original HAO solar observing group. The heliostat main housing was built by Carson Astronomical Instruments, with the remainder of the instrument custom-made or integrated by department personnel.
Dr. Bruce Bohannan became Observatory Director in 1974,
and in 1979 secured a grant of $360,000 from the Max C.
Fleischmann Foundation to construct a 4,000 square foot
addition to the building. Ground breaking took place on
January 24, 1980, and construction was completed in 1981.
The addition provided four darkrooms (the original darkroom
being converted into a reading room), a laboratory, several
offices, a workshop, and a large open observing deck. The Bausch refracting solar telescope was moved back from the Duane Physics Building and was remounted on the open observing deck of SBO, with optical feed to the laboratory room below.


Sommers­Bausch Observatory 8
The Fleischmann Foundation also granted funds for the purchase of an 18-inch Cassegrain reflector from DFM Engineering of Longmont, Colorado. The new telescope was installed in 1982 on the observing deck under a temporary roll-away shed instead of a dome.
In 1986 the University funded construction of a roll-off roof over 1200 square feet of the new addition observing deck, affording better protection for the 18-inch and providing cover for a second telescope. A 16-inch DFM reflector was subsequently acquired with University funds; the roof and telescope were dedicated in 1987.
That same year a Texas Instruments 800x800 pixel charge-coupled detector (CCD) – a twin to the first Hubble Space Telescope imaging detector - was acquired from the NSF and installed in a Photometrics camera control unit and interfaced to a Sun 3/180 computer. Support ancillaries for the new detector included a cryogenic cooling system, UV-sensitizing vacuum apparatus, and a QE measurement facility. The acquisition of a state-of-the-art CCD enables the Observatory to enter the modern age of electronic astronomy.
In 1989 the APS Department initiated a combined lab/lecture introductory astronomy course series, now called ASTR 1010/1020, which greatly expanded both the daytime and nighttime involvement at the Observatory by undergraduate students. The new series added 20 hours of
daytime student use and 6 hours of nighttime telescope use of the Observatory each week.
Dr. Catharine Garmany became the new Director of Sommers-Bausch Observatory and Fiske Planetarium in 1991, and working with Observatory Manager Keith Gleason continued to promote improved facilities for undergraduate astronomy education. The next several years saw a heliostat upgrade to provide narrowband two-color imaging of the solar chromosphere; the construction of an open-air 3-meter spectrograph for multi-person viewing of the solar spectrum; and extensive new undergraduate lab equipment including an SBIG ST-6 CCD. In the summer of 1994, a refurbishment of the aging 18-inch telescope control system was performed; and in the fall of 1995, a similar upgrade was made to the 16" telescope. The improvements occurred in time for the newly-introduced Accelerated Introduction to Astronomy series, ASTR 1030/1040, which held lab sessions in the Observatory classroom.
In 1997 the Observatory was renovated to provide space for a lab of Mac/PC computers; two years later that lab was converted to server-client technology using Sun (Unix) and Dell (Windows) servers; funding came from grants acquired by Drs. Fran Bagenal and Dick McCray.
About that same time the Department first offered a Bachelor's degree in Astronomy, which dictated that we also provide additional new observational courses at SBO: Observations & Instrumentation I/II, ASTR 3510/3520. The 24-inch telescope became dedicated to serving just this series of classes.
To support the new observational needs, new large format CCD cameras were integrated with the 24-inch telescope, which was also retrofitted with a new DFM control system similar to those available on the 16- inch and 18-inch telescopes. During this period of time, Dr. Erica Ellingson served for two years as interim


Sommers­Bausch Observatory 9
director of the Observatory, followed for four years by Dr. Doug Duncan, and five years by Observatory Committee Chair Dr. John Bally.
The year 2005 saw the culmination of decades of planning to modernize the 52-year-old dome. Ever since the 24-inch was installed over 30 years
earlier, observers have had to battle the
heat-trapping, seeing-disruptive,
vignetting effects of a too-narrow
observing slit – not to mention the
mechanical problems inherent in a system
involving 10 separate motors and 18
doors and flaps! The old slit was widened
an additional 8 inches and replaced with a
single-motor over-the-top slit designed
and built by Meyers Construction
Company. Eight cooling vents were also
added around the periphery of the dome to
help the telescope reach ambient
temperature more quickly at the beginning
of an observing run. Although this
modification somewhat changes the
exterior appearance of the Observatory,
few people will mourn the passing of the original and unique slit design, which at the time was thought to represent the wave of the future!
________
Today, six decades after its founding as a research extension of HAO, Sommers-Bausch Observatory provides daytime classroom and laboratory facilities for ten different sections of ASTR 1010 and four sections of ASTR 1030 or 1040; serves as a computer laboratory for lower and upper division classes including ASTR 2600 and 3800; is occupied almost nightly for telescope and instrumentation practice for majors in ASTR 3510 or 3520; provides nighttime observing opportunities for students taking the ASTR 1010, 1020, 1030, 1040, 1000, 1200 and 2000 courses; offers public viewing of the heavens every Friday evening when school is in session; and hosts summer instructional workshops, school tours, Science Discovery classes, an annual Astronomy Day public celebration, and special public observing events whenever interesting celestial happenings occur in the sky.
The introduction of Dr. Seth Hornstein as new director, and of Fabio Mezzalira as manager; building on a long, exemplary and distinguished career by Keith Gleason, will usher in a new future full of exciting opportunities for Sommers-Bausch Observatory and the students and community it serves.
For a pictorial synopsis of the history of SBO, visit the on-line Photo Gallery Scrapbook at
http:/sbo.colorado.edu/sbo/sboinfo/scrapbook/scrapbook.html


Sommers­Bausch Observatory 10
Room Location Guide


Sommers­Bausch Observatory
11
Main (Entrance) Level
Resources Room N175 Lounge N170 Director's Office N125 Manager's Office C150 Assistant's Office N101 Machine Shop N150 Workshop (Electronics) N101 Building Services
New Wing Electrical C101 Elevator & Telecom C103 Old Wing Heating N141 Custodial N161
Restrooms
Unisex Restroom N149
Unisex Restroom N151
Top (Dome) Level
24-Inch Telescope Dome N250 Storage C250 Darkroom #1 C201
Middle (Observing Deck) Level
Roll-Off Roof Deck S250 Open Deck Patio
Darkroom #2 C265
Lower (Laboratory) Level
Astronomy Laboratory S175 Computer Laboratory S125 Lab Supplies Room S160 New Wing Mechanical S165 Water Fountain Stairwell
Amenities & office supplies & fax machine Relaxation/ reference area for SBO users Seth's place
Fabio's place
Student assistant's place
Mechanical, large tools, storage Electronics, assembly, repair, supplies
Electrical breakers, water heater Telephone, fire, and elevator services Gas heating furnace
Cleaning & maintenance
Original restroom ADA compliant
Boller & Chivens research/training telescope Never enough space
AKA the "The Yellow Room"
16-inch and 18-inch telescope observing Heliostat, small telescopes, naked-eye observing
AKA the "Not-So Darkroom"
Main instructional astronomy laboratory
Cosmos & Scorpius computer lab, archival literature Lab apparatus and demonstration material
Heating and air conditioning for new addition Watering hole


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Resource Room
The Resources Room N175 is located just north of the Main Entrance to SBO. Access is by SBO BFDA2 building key, located in the adjacent lockbox.
Support equipment, office consumables, and teaching supplies are available in this room for use by instructors, TAs, LAs, and staff. You'll also find limited kitchen amenities.
The following can be found in the Resources Room:
Coffee Maker Microwave Refrigerator Copier
Papercutter First Aid Kit
Entrance Signs Office Supplies
CameraEquipment Checkout Log
Consumables (coffee, tea, hot chocolate, cream & sugar, cups, plates, plastic silverware, etc) are located in the cabinet below the pot. Donations to cover out-of-pocket costs are appreciated!
Users are responsible for cleaning up their splatter and messes! Same rule applies to coffee pot and refrigerator ... and everything else, for that matter. Maid service is not available!!!
Temporary storage of food and beverage. Please remove your stuff before it becomes a penicillin factory. Not responsible for use/consumptionbyothers. Freezerisunavailable(filmstorage).
TA, instructional, and administrative use. Student use allowed by permission only. Currently we do not require usage log, but please be frugal with supplies. User is responsible for reloading paper (bottom right shelf of supplies wall) as needed.
Caution! Please dispose of detached digits in trash, wipe up blood.
Located on top right supplies shelf. Additional First Aid Kits are located in the Equipment Storage room S160 and the Observing Deck closet.
Wall storage at entrance above light switch. Use or make signs as appropriate. Replace SBO Welcome sign when you are through!
On north wall bookshelves. Paper, envelopes, pens and pencils, paperclips, rubber bands, staples and staplers, tape, notepads, etc. Feel free to use the usual office stuff as needed for teaching support, but please notify the SBO staff if supplies run low. Also blank CD-ROMs and cases, 3-ring binders, astronomy observing aids, etc. Specialized materials may be reserved for specific class use; ask if in doubt.
Digital camera, camcorder, MP-3 Copy Camera. Right-hand cabinet beneath microwave. Contact Fabio for instructions.
Located on top of the microwave oven. You must sign out anything and everything that leaves the building, and sign it back in again when it is returned. See wall instructions. No exceptions, no leeway, no pardons, no mercy!


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Recommended Resource List
All items are available in SBO Lounge and/or at Telescopes. For complete list see http://sbo.colorado.edu/sbo/sboinfo/readingroom/readingroom.html
Celestial Object Information
SBO Catalog of Objects – 225 object listing including computer codes, sorted by
increasing right ascension. Includes the Messier and M&M listings plus others.
Finest Deep-Sky Objects (Mullaney & McCall) – the best objects for open houses and introductory student observing.
Burnham’s Celestial Handbook – 3 volumes, arranged by constellation. Everything you ever wanted to know about things in the sky, and then some.
The Messier Album - descriptions and photos of all Messier objects.
The Messier Card – coordinates and object types on a single card.
Sky Catalog 2000.0 - Hirshfeld, Sinnott
Vol I: Stars to Magnitude 8.0
Vol II: Double Stars, Variable Stars, Nonstellar Objects Webb Society Handbooks - listings and descriptions by object types.
Atlases and Skymaps
Norton’s Star Atlas – the most famous of the introductory atlases. Sky Atlas 2000.0 (Tirion) – the modern observer’s general atlas. Uranometria 2000.0 – for more detailed and fainter sky searching TheSky (software) – available on SBO PC machines & at telescopes Voyager (software) – available on SBO Mac machines
Periodicals and Annuals
Astronomical Almanac – tables of just about everything for the current year: Sun,
Moon, planets, satellites, eclipse details, twilight, etc.
Observer’s Handbook –more popular and readable than the Almanac Astronomy Magazine – monthly info on what’s up, popular
Sky & Telescope Magazine – more monthly info, popular to semi-technical Scientific American - Special topics and essay articles frequently on astronomy


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Telephones at SBO
The following phone lines are present in the building:
Observing Deck 24” Dome Student Lounge Computer Room Main Office Director's Office FAX/Resource
2-2020 From off-campus: 303-492-2020 Room S250, 16" & 18" Telescope
2-1946 From off-campus: 303-492-1946 Room N250, 24" Telescope
5-6003 From off-campus: 303-735-6003 Room N170, TA and Reference Area
2-2699 From off-campus: 303-492-2699
Room S125, COSMOS Lab and Reading Room
2-6732 From off-campus: 303-492-6732
Room C-150, Fabio Mezzalira (720-329-4482)
2-9105 From off-campus: 303-492-9105 Room N125, Seth Hornstein
2-2051 From off-campus: 303-492-2051 Room N175
Phones exist for University and Observatory business. Observers and students are welcome to use the lines for occasional personal use provided that the called are limited to 10 minutes or less. Long distance calls may not be placed from on-campus telephones unless the caller has been issued a long distance Authorization Code.
Most telephones at SBO are equipped with Abbreviated Dialing (also called "speed dialing") for emergency night contact of the appropriate personnel. The numbers that have been per- programmed for that phone are listed on the set. Recall that these numbers may awaken individuals (and their families) at home, and so should be used with prudence!
WWVTimeService(recordingfromNIST). UsefultoverifyUTTime.
Fabio Mezzalira, SBO Manager. Telescope troubleshooting, computer assistance. Alternate SBO contact (varies with semester). Emergency use only.
Current ASTR 3510/3520 instructor (varies with semester).
Current ASTR 3510/3520 TA (varies with semester).
UnixOps (2-6096). Report trouble with COSMOS Lab computers. PoliceNon-Emergency(2-6666). Inemergencydial911.
Facilities Management Service Desk (2-5522). Building and access problems.


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Daytime Parking
Parking at SBO
The Service Entrance Driveway (north end of the building) can be utilized for SBO staff, teaching assistants, LAs, and APS instructors provided all the following criteria are met:
(1) The owner/driver of the parked vehicle must be engaged in an activity directly supporting the Observatory's educational, research, or outreach functions, be maintaining the physical plant, or be providing for needed safety/security; and
(2) Be physically present within the Observatory building and available to move your vehicle as needed to provide access for service, delivery, or emergency vehicles, and also to permit vehicular ingress/egress by other SBO users. By special arrangement, exceptions may be allowed if the individual surrenders his/her car keys to the Observatory staff so that the vehicle can be moved if necessary; and
(3) Leave a sign in the automobile's window with the owner's name (and cell phone number if appropriate) so that they may be contacted to move the vehicle as needed.
Students are not permitted to use the Service Entrance Driveway for class attendance parking!
Bear in mind that this parking area is the sole vehicular service entrance for deliveries and maintenance at Sommers-Bausch Observatory. Even more significantly, the driveway/parking area provides the only emergency vehicle access (fire engines, ambulances, police) - to our building.
Because of the emergency and service nature of this area, anyone whose vehicle occupies an Observatory parking space or the service driveway for more than 15 minutes (the standard service parking limit) must comply with the above criteria. A flagrant repeat violator of these practical and reasonable rules runs the risk of losing his/her privilege to use the parking area entirely, and in extreme cases, may have their vehicle subjected to tow.
Nighttime Parking
Because of safety and security issues, nighttime observers and teaching assistants who conduct late- night sessions are encouraged to make use of the service parking area at the north doors of SBO. The short walking distance from building to vehicle was a prime factor in convincing Parking Management to allow SBO users to have use of this area. However, this parking area is not available for general student use even at night. The rules for daytime parking still apply.
Additionally, the hilltop parking area #419 immediately to the east the Speech & Hearing building is generally available for night parking (a lot permit is required 7:30 am to 5:00 pm M-F), and involves only a 1-minute walk to get to the Observatory. (Warning ... you may not park in the area marked #418 (Kitt Zone) or in handicapped parking spaces, day or night, without the appropriate hang tag.)
Occasionally Lots 418/419 are used for evening Coors Event Center special events parking (at a $5 charge) and hence may not be available for general public use on a particular night. TAs who are holding evening observing sessions and need vehicular access to the SBO service entrance should simply explain their situation to the parking attendant ... almost inevitably they will allow you to pass with no charge and with no hassle. If your valid access is denied, however, please let Fabio know about the situation, and we will work with Parking Management to remedy the problem in the future.


Sommers­Bausch Observatory 16
Audio, Video, & Computer Connections UCB Campus Wireless
Wireless via the CU campus computer network is available throughout the building. Some locations inside metallic areas (such as the dome) may have poor reception. All students and CU staff should have access via their Identikey login; temporary guest accounts can also be established. For more details see campus Information Technology Services (ITS) http://www.colorado.edu/its/wireless/index.html
Overhead Projector – Astronomy Lab S-175
The Remote (labeled “LCD Projector”) turns projector on/off (red button) and selects an input from one of the following:
 A/V Cabinet feed - press Video button on the remote
 Front-Desk Cosmos Computer - press Comp 1 button on the remote
 Auxiliary Laptop Computer - press Comp 2 button on the remote
If using the Auxiliary connection (Comp 2), connect your laptop secondary video output to the spare VGA video port. If you have a Mac, you may need a video adapter (kept in the SBO Storage Room S160; contact Fabio if you can’t find it) to convert from VGA to your particular video output (DVI/HDMI).
Warning: successful projector connections are very machine-dependent. Don’t expect the SBO staff to be familiar with your particular laptop connection quirks and how to overcome them! Test making a connection in advance; attempting a last-minute untested hookup is an invitation for delay and frustration. The SBO staff will be happy to help you as best we can, but you know that old saying about “poor planning on your part ....”!
In general, it’s good practice to connect your secondary video output before booting your laptop, but after the projector is set to expect an input from that source – this permits your laptop’s auto- detect system (if so equipped) to find the projector. Also, most laptops will not provide a second- video feed if operating from battery power, so be sure bring your charger cord. Finally, you may have to force your laptop to drive the second video feed via a Special Function key command – but again, don’t ask us how, it’s your computer, not ours!
Overhead Projector – Cosmos Lab S-125
The Remote (labeled “PROJ)” turns projector on/off
The Switchbox selects an input from one of the following:
 The Cosmos computer at the instructor’s desk - select A
 Auxiliary Laptop Computer – select B
If using the Auxiliary connection (B), connect your laptop secondary video output to the VGA video cable from the Switchbox. If you have a Mac, you may need one of the white video adapters from the S160 Storage Room to convert from VGA to your particular video output (DVI/HDMI).


Sommers­Bausch Observatory 17
Audio/Video Cabinet – Astronomy Laboratory S-175
The A/V cabinet is an extremely versatile system with up to 8 separate A/V signal inputs able to be simultaneously routed to as many as 8 separate A/V output devices. However, with versatility comes a bit of complexity. Not only does the user need to understand how to use the 8x8 Kramer Switching System, but also s/he needs to understand how to utilize the particular A/V components that are being utilized. There is a detailed A/V user’s manual in the cabinet, which describes our system and includes all component manuals. First-time users are strongly advised to consult both the manual and the SBO staff before attempting a class presentation!
Possible signal sources can be derived from
 Television Receiver – the closed-circuit campus cable network, any valid channel
 DVD player, VCR tape player or the TLR (time lapse recorder) tape playback
 Heliostat video feed (real-time sun images from SBO’s solar telescope)
 Spare Auxiliary Input, Laserdisk Player (obsolete)
 CD Player/ Radio Receiver (audio channel only)
Each of those signals can then be switch-directed to one (or more!) of the following outputs
 LCD Overhead Projector
 Television - Video 1 port, Video 3 port
 VCR and/or TLR tape recording
 Feed to Fiske Planetarium Theater
 Spare Auxiliary Output
 SBO Lab Room Speaker System (audio only)
 Repeat above sequence for each input/output pair. Many things routed simultaneously.
SINGLE INPUT CONFIGURATION (Simplest; one input is directed to all 8 outputs):
 Press the ALL button (bottom left of Kramer Switcher) – all channel LEDs blink
 Press the one INPUT device button (bottom row) that will provide the signal source
 Turn on only those output devices that you really want to use for your presentation; the
other channels don’t matter!
For example, to route a movie playing on the DVD (Input 2) to the LCD Projector (Output 2) with good Speaker Sound (Output 8), select “ALL 2”, then turn on and load the DVD player, the LCD Projector (see above), and the CD/Receiver/AudioAmp unit set to “Aux” – which powers the lab room speaker system.
MULTIPLE INPUT CONFIGURATION (can get complicated!)
 Select the OUTPUT device first (top row) – the corresponding channel digit will blink
 Select the INPUT device second (bottom row) – the channel digit shows your choice
 Repeat the above two steps for additional simultaneous routing as needed.
Warning! Unless you’re a broadcast systems engineer proficient in doing voice-overs, stay away from the “Take – Video – Audio – AFV” buttons: if the AFV (“audio follows video”) button stays lit, signals will probably go where you want them to!


Sommers­Bausch Observatory 18
Keys and Access Gaining Access to the Building and Rooms
Most access arrangements are made with incoming personnel at the beginning of the new Fall semester's SBO Workshop. No new or updated clearances will be issued to any user for any reason whatsoever until s/he has complete an SBO User Information Sheet and has had his/her photograph taken for inclusion therein!
Buff-One Card
The Buff-One Card is the principal form of building access available to most users. The card readers are programmed by SBO staff to only permit access to currently-approved CU personnel. Individuals not directly affiliated with CU may request Buff-One cards under special circumstances. Generally, card access privileges will be terminated at the end of the school year if the user does not have ongoing affiliation with the Observatory and/or the APS Department.
Cards provide access to the following via the card readers next to the doorways:
 Front (Main East) Entrance
 Astronomy Laboratory (S-175)
 Cosmos Computer Laboratory (S-125)
 Observing Deck, 16” & 18” Telescopes (S-250)
 24” Telescope Dome (N-250)
To Use the Card: Remove the card from the RTD protective sleeve, if applicable. Orient the card as though you were going to read it, then tilt it vertically to the left (counterclockwise) and swipe it through the slit. (If you get no response, the magnetic stripe was oriented incorrectly.)
Keypad Alternative: Press CMD/ENT, followed by the last seven digits on your Buff-One Card, followed by CMD/ENT again.
Card-reader status lights are as follows:
Yellow: Door is locked and waiting for card entry.
Green: Door unlocks temporarily for you to pass. Note: door handles do not rotate; instead, entry is accomplished by releasing the door-jam catch. Just push on door to enter.
Green Blink: Door is already electronically unlocked. No card is needed.
Red: Card was misread, or you do not have permission to enter. Try swiping again
slowly. See Fabio if there is a continued problem.
Note: The Observing Deck is automatically unlocked by the building security system Mondays through Fridays at 8 a.m., and relocked at 11 p.m. This permits students and visitors to come and go through this exterior door without having to worry about it locking behind them. Be aware, however, that after 11 p.m. the door will lock and card access will then be required!


Sommers­Bausch Observatory 19
Lockbox Key
Most Observatory rooms use a regular key rather than a card; these include the Resources Room, the Student Lounge, the Equipment Storage, the Observing Deck Equipment Closet, the Darkrooms, and the Machine and Electronic Shops. To gain access, users must acquire a BFDA2 door key contained in one of three lockboxes located throughout the building:
 Resources Room
 Lab Equipment Room
 Observing Deck Closet
Main entrance hallway, across from the curved blackboard. Lower level hallway, between the S-175 and S-160. Middle level, on Observing Deck to right of 16” telescope.
To open a lockbox, punch in the current 4-digit Building Access Code and press down on the central latch and rotate the cover outward to get the key. Leave the key affixed to the lockbox cover; this will help remind you to return it to the lockbox after use.
Note: you must re-punch the same 4 digits to reattach the lid back to the box. Failure to return the key to the lockbox after use is a serious procedural infraction and will be dealt with severely!
The SBO Building Access Code may be changed annually just before the Fall SBO Workshop. If you need access and are unsure of the current code, contact the Observatory staff in advance to obtain the information.
Cabinet Combination Locks
Throughout the Observatory you will encounter cabinets and equipment covers which are locked with a 4-digit combination padlock. For example, all small telescope storage cabinets, and the open deck heliostat cover, are all secured with these combination padlocks.
The four digits required to open the padlocks are the same as the current Building Access Code. Note: after dialing in the code, squeeze the lock hasp inward to free the tumblers ... then release and the lock will spring open. To re-lock, the correct code must still be in the tumblers before the hasp will close. Be sure to spin the dials to scramble the code and lock the padlock.
Keys for Other Access
The Observatory maintains additional keys, under separate lock, which would normally never be required except in an emergency. If you encounter an unusual situation wherein you need additional access (for example, to reset a circuit breaker, or to perform a telescope interlock override), contact Fabio to get instructions as to where to find the key and how to use it.
FYI: In case you’re curious, the black keypads found on several doors are from an earlier generation of monitored security access to rooms, and are being phased out by campus Access Services. These are only available to SBO staff.


Sommers­Bausch Observatory 20
Personal Security
Safety and Security
PersonalsafetyandsecurityistheprimaryobjectiveoftheusersofSBO. Onlyafterhumansafetyis assured should you be concerned with building and equipment safety; and only after physical plant safety is assured should you feel free to go about the business of education and outreach.
Students (and TAs!) are strongly encouraged to walk in pairs or groups to and from the Observatory at night. However, TAs should not offer to give students a ride home in their vehicle; such actions place them, as persons in a position of authority, at risk for liability from the students themselves. Students may contact Nightride at 2-SAFE ([303-49]2-7233) to arrange for transportation.
Remember, even being in the Observatory building is no guarantee of personal safety. Because of the nature of working late at night when people are tired, in the dark and with heavy equipment, astronomy is one of the most dangerous professions! This is why we require all Observatory users be accompanied by at least one other individual – otherwise if you are alone and injured, it may be many hours before you are found and assistance can be rendered!
Be very aware where people are, and insure that they are well clear of danger, especially whenever the Deck Roof or 24-Inch Dome is in motion!
In an emergency call 911. If a situation seems to be developing about which you are feeling uneasy, you are encouraged to call the CU police at 2-6666. Better to be safe than sorry; trust your instincts.
Telescope Security
Insure that building interior doors not used for access are closed and locked. In essence, treat the building like a ship at sea during "general quarters" ... lockdown and compartmentalize to minimize damage and loss.
A good rule of thumb when dealing with telescopes is ... "when in doubt, don't"! Your intuition about when things are safe or not should be your principal guide.
You can always contact the staff if you are unsure if you should proceed on a given night. However, while in charge of the telescopes, you are the safety and security officer for the building, and sound common sense usually dictates the best and proper course of action.
Rain/Snow – A small amount of accidental moisture probably won't damage a telescope; however, in inclement weather you must always keep an eye on the skies and be prepared to cover/close at a moment's notice. In the possible presence of moisture, do not leave the telescopes unattended. Do not allow yourself to be pressured by students and visitors to put the equipment at risk from water damage as you chase "sucker holes" ... in such cases, the night is usually more frustrating than educational anyway.
High Wind – We usually recommend that you not use the Observing Deck with winds in excess of 30 mph (40 mph for the Dome, if the slit is oriented in the leeward direction). These limits are rough guides only ... use your common sense. If the telescopes are being buffeted and people are having problems getting their eye lined up with the eyepiece, ask yourself "is there any educational value in staying open any longer?" However, the only hard rule about wind is: if you can see particulates flying past the telescope, shut down. There is danger of abrasion to the optics.


Sommers­Bausch Observatory 21
Building Security
The authorized Observatory user is responsible for unlocking the building for access by his/her class and/or group, and for re-locking it again at the end of that use.
If the building is occupied by other valid users when you are ready to leave, it is your duty to inform them of your leaving, and to obtain a verbal commitment from the other user(s) that they are assuming responsibilityforthebuilding'ssecurityuponyourdeparture. Ifthebuildingistobeleftunoccupied, even for a few minutes, you must lock it up completely.
Do not assume that a door is locked just because you didn't open it. Don’t assume that others know you're leaving, and that they’re now in charge: assume nothing, confirm everything!
Warning: exterior doorways except for the main entrance do not lock open. If needed to remain open, they must be propped with a floor kick-stop, wedge, or hook, as provided. It is possible for the user to become locked out of the building via these exterior self-closing doorways!
The following are external access doors to SBO. It is the user's obligation to check and lock these exterior doorways when the building is vacated, and also to insure that interior doors are also closed and locked as well.
1. Front Entrance – Access by key or Buff One Card. Door is unlocked/relocked by pushing in on the panic bar and using the Allen wrench hanging on the display case next to Fabio's office (C-150). InserttheAllenheadintotheopeningtotheleftofthepanicbar(whiledepressingthe bar) ... clockwise 1/4 turn unlocks the door for others to enter, counterclockwise 1/4 turn re- locks. Always return the wrench to its hanger after use.
2. North Service Entrance / Emergency Exit - Double-doors by the restrooms. Key entrance only, panic bar exit. Cannot be unlocked, but users should insure that both doors are latched securely at the end of the night (when you go to turn off the north hallway lights). Numerous thefts have occurred through this door!
3. Covered Observing Deck – S-250. Buff One Card access to the 16- and 18-inch telescopes. This door is automatically unlocked 8 am – 11 pm M-F. Make sure the door is fully closed so that the locking mechanism will engage at 11 pm.
4. Open Observing Deck – Double doors leading from the covered observing deck to the heliostat and small telescope piers. Key operated only (and it's easy to get trapped out there!). Latch left door open using the chain when in use. Always check to see that nobody is left trapped on the deck when you close down for the night! Be aware that rock climbers have been known to scale the exterior walls to use the Open Deck patio facilities; if this door is not secure, they gain direct access to the telescopes.
5. Emergency Deck Exit - North wall of the Covered Observing Deck next to the 18-inch telescope console. Panic bar exit, key entrance. Frequently overlooked by Observing Deck users; be sure to check at the end of the night.
6. Emergency Lab Room Exit – Room S-175, southwest corner near sink. Panic bar exit, no entrance. Security alarm system is for show; it no longer works. Lab equipment can disappear through this exit, so be vigilant!
7. Catwalk – From 24-inch computer room N250B. Key operated only, may be latched open at base of door. If you get trapped out there without a key, your only recourse is to shout for assistance, use a cell phone, or to climb down the rock wall ... very dangerous at night! However, people have gained entrance to the building by climbing to the catwalk, so 24-inch users should insure that this door is closed and locked at the end of their session.


Sommers­Bausch Observatory 22
Friday Night Open House
For over a half-century, Sommers-Bausch Observatory has offered free public viewing of the celestial sky every Friday evening that school is in session. Tens of thousands of visitors have participated in these weekly star parties over the years, from families with children, to formal groups on field trips, to students who’ve always been curious about what’s inside the dome, to “townies” who enjoy a nice evening under the stars and a stimulating conversation about astronomy. See more at http://sbo.colorado.edu/sbo/public/openhouse.html
Hosting
Each Friday evening session needs to be hosted by two (or more) qualified telescope operators, who also need to be able to “talk astronomy” to interested parties. Typically the event is manned by two grad students, though there may be a faculty member signed up as well, a “trainee” who is there to gain hands-on experience to become a qualified host, or a previously checked-out member of the local amateur astronomy society.
Although we do understand that graduate and undergraduate students have a very busy schedule, hosting Open House Nights is an enjoyable activity that also will also provide valuable experience to help you develop your professional, instructional, and interpersonal skills. Hence:
First-year graduate students who have completed the SBO Telescope Training are expected to “volunteer” for a minimum of two (2) Friday Night Open Houses during the course of their first year (fall, spring, and/or summer semesters).
Nth-year graduate students (where N>1) are expected to volunteer at least one (1) night a year.
Other individuals (faculty members, checked-out Learning Assistants, undergraduates having completed ASTR 3510/20 Observational Astronomy, experienced amateur astronomers) are highly encouraged co-host if both qualified and interested.
Signup for hosting is accomplished on-line via the Local Access Page of the APS Website http://aps.colorado.edu/ or by directly accessing the page at https://aps.colorado.edu/local_openhouse.shtml .
Hours
Starting times vary from 8 pm in the winter, to 8:30 pm in the spring and fall, to 9 pm during the summer. Typical observing sessions run for about 1.5 to 2 hours, but that decision is up to the host based on the actual circumstances of the evening – with the following provision:
Rain or Star-Shine
Although Open Houses are billed as “weather permitting”, hosts are still expected to be present for at least one half-hour after the end of the Fiske Planetarium show – regardless of the weather. Fiske invites the public to drop into SBO after their Friday evening presentation - and they can’t tell if it’s cloudy from inside the theater. Hosts don’t have to open up the telescopes, just the front door! Furthermore, some people may have driven a great distance to attend, and the weather might have been favorable when they left. Also some folks don’t know that telescopes can’t see through clouds, so this becomes a “teachable moment”. Or, they may simply want to look at the telescopes and “talk astronomy”. In any case, to avoid disappointment and bad public relations, you MUST give our guests the courtesy of your presence!


Sommers­Bausch Observatory 23
Frequently Asked Questions Where is Lost & Found?
The general Lost & Found is located in the Astronomy Lab underneath the cabinet sink. Useful for items of apparel, notebooks, papers, other personal (but not necessarily valuable) items.
If you find something of general value (electronic device, iPod, calculator) or an item with contains sensitive information (driver’s license, wallet, Buff-One Card), please turn it over to instead to Fabio for safekeeping. Alternately, you may turn it over to the Police Department (2- 6666), but let Fabio know that you have done so in case the owner comes looking.
Who do I call in an emergency?
When in doubt, do not hesitate to call 911 to obtain medical or police assistance as fast as possible. Then call SBO personnel as soon as possible. We trust you to use your best judgment in handling the situation, and the SBO staff will back you up in your decision.
Are first aid kits available?
Yes, First Aid kits can be found in
 Resources Room (N175) – main level (includes eyewash and tourniquets)
 Lab Supplies Room (N160) – lower level
 Observing Deck (S250) closet – middle level
What if there’s a telescope problem at night?
First, don't panic! Troubleshooting is best accomplished with a cool, calm, analytical approach. Next, check to see if there is a troubleshooting guide at the back of the Operations Manual for
that equipment.
If that doesn’t help, your next best bet is to call Fabio. But use your good judgment about the severity of the problem and the time of night, to help you decide whether to place the call! Remember you may be waking other family members as well.
Early in the evening, you should feel free to phone for advice. Late in the evening, call if it's a problem with equipment safety, or appears to be a genuinely serious issue. Otherwise, put the telescope to bed, close up, and fill out a detailed malfunction report (from the on-line logout procedure) so that problem can be addressed first thing the next morning.
However, if anything is deemed to be a threat to the safety and security of personnel, the building, or the telescopes, do not fail to call at any time of the day or night! It is your duty to notify an appropriate authority before you are permitted to leave! If you require immediate additional help, or if you cannot reach the appropriate SBO personnel, you should contact the Facilities Management hotline (2-5522) and/or the police (2-6666).


Sommers­Bausch Observatory 24
What if I forgot to shut down the telescope or close up the building?
That's a no-brainer. It’s your duty to go back in and fix it! That's why we encourage you to stop, look, and listen as you exit and lock up and check each and every door of the Observatory when leaving ... so you won't have to experience this particular irritation and inconvenience.
Of course there might be someone still there, in which case you could call SBO and ask that person to fix your problem for you. But no matter what, you not permitted to ignore the problem and hope it will go away!
What if I forgot to logout or file a Malfunction Report?
You can fix that problem from home via the Internet:
• Check on current telescope status:
http://sbo.colorado.edu/special/sboTelescopeStatus.html
• Log out of a telescope:
http://sbo.colorado.edu/special/sboLogout.html
• Fill out a malfunction report:
http://sbo.colorado.edu/special/problemReport.html
• Review the records of a telescope log:
http://sbo.colorado.edu/special/sboViewLogs.html
Can I use/check out telescopes for personal use?
Sure! Incoming grad students, TAs, and LAs are usually surprised to learn that personal use of the Observatory's telescopes is not only tolerated, but encouraged. Your class instructional abilities under the stars will be greatly enhanced with experience ... and the only way to gain hands-on experience with a telescope is to actually use it! This applies to CCD and photographic imaging, as well as just general stargazing and "sky surfing" to investigate new objects to add to your repertoire of things to look at.
Of course, private use must always defer to educational needs. Bumping priority is as follows: class teaching (including TA practice) takes priority over research use, and research use takes priority over personal use. Unscheduled users with a lower priority at the telescope must relinquish the telescope to higher-priority users, on-demand and at any time that is requested.
Educational demonstration equipment, small telescopes, tools, and other Observatory materials may be removed from the building on loan, but only after completing all necessary entries in the SBO Equipment Checkout Logbook, which can be found in the Resources Room. Prior arrangements must be made to insure that the material removal will not conflict with class use, which always takes highest priority. This is especially true for small telescopes, audio/video equipment (camera, camcorder), tools, and reading room materials.
Checkout Log information must include the following
 Borrower's name, phone number, e-mail address
 What is being checked out (include all related ancillaries – be specific)
 Where it will be located (field trip site, etc)
 For what purpose is it being used (personal use is OK, but we want to know)
 When it will be returned (we'll hold you to it!)


Sommers­Bausch Observatory 25
Upon returning you'll also be required to
 Sign the logbook with the date of the return
 Inform the SBO staff of any problem or damage
 Return the equipment to its proper location
Failure to properly comply with loan procedures will result in loss of future privileges!
Can I change the room temperature?
Please don’t. If there is a heating or cooling problem, contact the SBO staff.
The entire building's climate control (heating and cooling) is regulated by only two thermostats. Heating and cooling of the Fleishmann Addition (south wing) are regulated by a single thermostat in the Astronomy Lab near the sink. Old building (north wing) heating (there is no air conditioning) is controlled by a thermostat near Office N125.
Changed settings not only affect the current room occupants, but other current and subsequent building occupants as well. A frequently-employed tactic is to cool or heat the room by opening windows. We have no objection to this approach provided that the windows are closed again at the end of the class. Left-open windows defeat the Lab Room's thermostat control ... and that affects the climate of the entire building wing, not just the Lab itself!
Why am I expected to straighten up at the end of class?
Well, it’s a dirty job, but somebody has to do it. Why should it be the next guy?
And the custodial staff is scheduled to clean classrooms only once a week. The place can get
pretty messy before then.
And the SBO staff gets irritated when people expect us to clean up after them. And it’s the courteous thing to do.
So:
 Have tabletops cleared of trash and debris. Custodians aren’t allowed to remove things from desktops, lest they discard away student papers or valuable documents.
 Erase the blackboard and whiteboard. Custodians aren’t permitted to erase words or formulae, lest they destroy the ruminations of the next Einstein. Besides, old whiteboard markings can leave permanent stains.
 Return chairs to their proper places. Only five displaced-and-replaced chairs per class session maps into 20 chairs per day, or 100 chairs straightened up at SBO every week. That’s 3,000 chairs per year, or nearly 100,000 chairs in the career of tired old Observatory managers. Time for you folks to take over for awhile!
Of course, if your students made the mess, you have every right to expect them to pick up after themselves, instead of you having to do it. How you achieve that is up to you.


Sommers­Bausch Observatory 26
Telescopes & Observing Equipment
see on­line manuals located at
http://sbo.colorado.edu/sbo/telescopes/telescopes.html
Permanently Pier-Mounted
24-Inch Telescope (6" Guidescope, 4" Finder)
Manufacturer:
Design:
Aperture:
Effective Focal Length: Effective Focal Ratio:
Boller & Chivens (1973) Reitchey-Cretien (modified Cassegrain) 0.61 m (24 inches)
4.877 m (192 inches)
f/8
18-Inch Telescope (8" Piggyback Meade)
Manufacturer:
Design:
Aperture:
Effective Focal Length: Effective Focal Ratio:
DFM Engineering (1982) Cassegrain Reflector
0.45 m (18 inches)
3.66 m (144 inches) or f/8 or
6.86 m (270 inches) f/15
16-Inch Telescope (3” Finder Scope)
Manufacturer:
Design:
Aperture:
Effective Focal Length: Effective Focal Ratio:
10-Inch Heliostat
Manufacturer:
Design:
Aperture:
Prime Focus Focal Length: Prime Focus F/Ratio:: Modes:
DFM Engineering (1986) Cassegrain Reflector
0.41 m (16 inches) 4.88 m (192 inches) f/12
Carson Engineering (ca 1975) + SBO Custom Big Bear Solar Observatory Achromat
0.26 m (10.25 inches)
4.9 m (approx) (150 inches)
f/15
Prime focus, large white light, small white light, spectroscopy,
H-alpha & Ca K narrowband imaging, spectrohelioscope


Sommers­Bausch Observatory 27
Portable Field Telescopes 8-Inch Meade
Manufacturer: Design:
Aperture:
Focal Length: Effective Focal Ratio:
Meade (ca 1985) Schmidt Cassegrain
0.20 m (8 inches) 2.0 m (80 inches) f/10
Schmidt Camera (Piggyback Mountable, no Tripod)
Manufacturer: Design:
Aperture:
Focal Length: Effective Focal Ratio: Film Format :
C-5 Telescopes (2)
35 mm
Celestron (<1975)
Schmidt Camera
0.20 m (8 inches)
0.30 m (12 inches)
f/1.5
, 680 arc-sec/mm,. Field 4.5° x 6.8°
Celestron International (circa 1973) Schmidt-Cassegrain
0.125 m (5 inches)
1.25 m (50 inches)
f/10
Manufacturer:
Design:
Aperture:
Effective Focal Length: Effective Focal Ratio:
Meade ETX-125EC Telescope
Manufacturer:
Design:
Aperture:
Effective Focal Length: Effective Focal Ratio:
Meade (2001) Maksutov-Cassegrain 0.125 m (5 inches) 1.900 m (74.8 inches) f/15
Orion 4.5” Starblast Alt-Azimuth
Manufacturer:
Design:
Aperture:
Effective Focal Length: Effective Focal Ratio:
Edmund Astroscan
Manufacturer:
Design:
Aperture:
Effective Focal Length: Effective Focal Ratio:
Orion (2004)
Newtonian Reflector 0.113 m (4.5 inches) 0.450 m (18 inches) f/4
Edmund Scientific (2001) Newtonian Reflector
0.108 m (4.25 inches) 0.454 m (18 inches) f/4.2


Sommers­Bausch Observatory
28
Questar 3.5-Inch Telescopes
Manufacturer:
Design:
Aperture:
Effective Focal Length: Effective Focal Ratio:
(3)
Questar (<1975) Maksutov-Cassegrain
Sunspotter Portable Solar Telescope
Manufacturer:
Design:
Aperture:
Effective Focal Length: Effective Focal Ratio:
Not Specified (2004) Folded-Optics Keplerian Refractor 0.057m(2.25 inches)
0.700 m (27.6 inches)
f/12
0.089 m 1.3 m f/14.4
(3.5 inches)
(50 inches)
(f/28.8 with internal Barlow)
Bushnell Reflector (Demonstration Scope – not recommended for use)
Manufacturer:
Design:
Aperture:
Effective Focal Length: Effective Focal Ratio:
Bushnell
Newtonian Reflector
0.100 m (4 inches) 0.600? m (24? inches) f/6?
German Equatorial Refractor (Demonstration Scope – not recommended for use)
Manufacturer:
Design:
Aperture:
Effective Focal Length: Effective Focal Ratio:
Towa? (<1975?)
Refractor
0.075m(3 inches)
1.2? m (48? inches) f/16?
Ancillaries for Portable/Remote Observing Applications
Battery Powerpack (12/18 Volt) for Field Operation, with charger 115 VAC to 12 VDC Power Supply
12 VDC to 115 VAC Converter, 300 Watt
Binoculars (Various: 25x100, 20x80, 16x70, 7x50s) Downlooking Binocular Stand (Gemini Mount)
Miscellaneous Telescope & Camera Tripods Parallelogram Binocular Tripod Stands Field-Trip Toolbox


Sommers­Bausch Observatory 29
Celestial Coordinates GEOGRAPHIC COORDINATES
The Earth's geographic coordinate system is familiar to everyone ­ the north and south poles are defined by the Earth's axis of rotation; equidistant between them is the equator. North­south latitude is measured in degrees from the equator, ranging from ­90° at the south pole, 0° at the equator, to +90° at the north pole. East­west distances are also measured in degrees, but there is no "naturally­defined" starting point ­ all longitudes are equivalent to all others. Humanity has arbitrarily defined the prime meridian (0° longitude) to be that of the Royal Observatory at Greenwich, England (alternately called the Greenwich meridian).
Each degree (°) of a 360° circle can be further subdivided into 60 equal minutes of arc ('), and each arc­ minute may be divided into 60 seconds of arc ("). The 24­inch telescope at Sommers­Bausch Observatory is located at a latitude 40°0'13" North of the equator and at a longitude 105°15'45" West of the Greenwich meridian.
North Pole +90° Latitude
Greenwich 0° Longitude
Boulder
+40° 0' 13" Latitude +105° 15' 45" Longitude
Equator 0° Latitude
The Earth's Latitude - Longitude Coordinate System
Parallels or Small Circles
ALT­AZIMUTH COORDINATES
The alt­azimuth (altitude ­ azimuth) coordinate system, also called the horizon system, is a useful and
convenient system for pointing out a celestial object.
One first specifies the azimuth angle, which is the compass heading towards the horizon point lying directly below the object. Azimuth angles are measured eastward from North (0° azimuth) to East (90°), South (180°), West (270°), and back to North again (360° = 0°). The four principle directions are called the cardinal points.
Meridians


Sommers­Bausch Observatory 30
Next, the altitude is measured in degrees upward from the horizon to the object. The point directly overhead at 90° altitude is called the zenith. The nadir is "down", or opposite the zenith. We sometimes use zenith distance instead of altitude, which is 90° ­ altitude.
Every observer on Earth has his own separate alt­azimuth system; thus, the coordinates of the same object will differ for two different observers. Furthermore, because the Earth rotates, the altitude and azimuth of an object are constantly changing with time as seen from a given location. Hence, this system can identify celestial objects at a given time and location, but is not useful for specifying their permanent (more or less) direction in space.
In order to specify a direction by angular measure, you need to know just how “big” angles are. Here’s a convenient “yardstick” to use that you carry with you at all times: the hand, held at arm's length, is a convenient tool for estimating angles subtended at the eye:
4°
3°
2°
Index Finger
1°
8°
18°
Hand
EQUATORIAL COORDINATES
10° Fist
Standing outside on a clear night, it appears that the sky is a giant celestial sphere of indefinite radius with us at its center, and upon which stars are affixed to its inner surface. It is extremely useful for us to treat this imaginary sphere as an actual, tangible surface, and to attach a coordinate system to it.


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The system used is based on an extension of the Earth's axis of rotation, hence the name equatorial coordinate system. If we extend the Earth's axis outward into space, its intersection with the celestial sphere defines the north and south celestial poles; equidistant between them, and lying directly over the Earth's equator, is the celestial equator. Measurement of "celestial latitude" is given the name declination (DEC), but is otherwise identical to the measurement of latitude on the Earth: the declination at the celestial equator is 0° and extends to ±90° at the celestial poles.
The east­west measure is called right ascension (RA) rather than "celestial longitude", and differs from geographic longitude in two respects. First, the longitude lines, or hour circles, remain fixed with respect to the sky and do not rotate with the Earth. Second, the right ascension circle is divided into time units of 24 hours rather than in degrees; each hour of angle is equivalent to 15° of arc. The following conversions are useful:
24 h = 360° 1h = 15° 4m = 1°
1 m = 15' 4s = 1' 1s = 15"
The Earth orbits the Sun in a plane called the ecliptic. From our vantage point, however, it appears that the Sun circles us once a year in that same plane; hence, the ecliptic may be alternately defined as "the apparent path of the Sun on the celestial sphere".
The Earth's equator is tilted 23.5° from the plane of its orbital motion, or in terms of the celestial sphere, the ecliptic is inclined 23.5° from the celestial equator. The ecliptic crosses the equator at two points; the first, called the vernal (spring) equinox, is crossed by the Sun moving from south to north on about March 21st, and sets the moment when spring begins. The second crossing is from north to south, and marks the autumnal equinox six months later. Halfway between these two points, the ecliptic rises to its maximum declination of +23.5° (summer solstice), or drops to a minimum declination of ­23.5° (winter solstice).
As with longitude, there is no obvious starting point for right ascension, so astronomers have assigned one: the point of the vernal equinox. Starting from the vernal equinox, right ascension increases in an eastward direction until it returns to the vernal equinox again at 24 h = 0 h.
North Celestial Pole +90° DEC
16h
18h
Hour Circles
4h
Celestial Equator 0° DEC
20h
RA 22h
Earth
24h = 0h
Ecliptic
23.5°
2h
Vernal Equinox
0h RA, 0° DEC
Sun
(March 21)
Winter Solstice
18h RA, -23.5° DEC


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The Earth precesses, or wobbles on its axis, once every 26,000 years. Unfortunately, this means that the Sun crosses the celestial equator at a slightly different point every year, so that our "fixed" starting point changes slowly ­ about 40 arc­seconds per year. Although small, the shift is cumulative, so that it is important when referring to the right ascension and declination of an object to also specify the epoch, or year in which the coordinates are valid.
TIME AND HOUR ANGLE
The fundamental purpose of all timekeeping is, very simply, to enable us to keep track of certain objects in the sky. Our foremost interest, of course, is with the location of the Sun, which is the basis for the various types of solar time by which we schedule our lives.
Time is determined by the hour angle of the celestial object of interest, which is the angular distance from the observer's meridian (north­south line passing overhead) to the object, measured in time units east or west along the equatorial grid. The hour angle is negative if we measure from the meridian eastward to the object, and positive if the object is west of the meridian.
For example, our local apparent solar time is determined by the hour angle of the Sun, which tells us how long it has been since the Sun was last on the meridian (positive hour angle), or how long we must wait until noon occurs again (negative hour angle).
If solar time gives us the hour angle of the Sun, then sidereal time (literally, "star time") must be related to the hour angles of the stars: the general expression for sidereal time is
Sidereal Time = Right Ascension + Hour Angle
which holds true for any object or point on the celestial sphere. It’s important to realize that if the hour angle is negative, we add this negative number, which is equivalent to subtracting the positive number.
For example, the vernal equinox is defined to have a right ascension of 0 hours; thus the equation becomes
Sidereal time = Hour angle of the vernal equinox
Another special case is that for an object on the meridian, for which the hour angle is zero by definition. Hence the equation states that
Sidereal time = Right ascension crossing the meridian
Your current sidereal time, coupled with a knowledge of your latitude, uniquely defines the appearance of the celestial sphere; furthermore, if you know any two of the variables in the expression ST = RA + HA , you can determine the third.
The following illustration shows the appearance of the southern sky as seen from Boulder at a particular instant in time. Note how the sky serves as a clock ­ except that the clock face (celestial sphere) moves while the clock "hand" (meridian) stays fixed. The clock face numbering increases towards the east, while the sky rotates towards the west; hence, sidereal time always increases, just as we would expect. Since the left side of the ST equation increases with time, then so must the right side; thus, if we follow an object at a given right ascension (such Saturn or Uranus), its hour angle must constantly increase (or become less negative).


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= Right Ascension on Meridian
Vernal Equinox
0 h 0m
22h 40m Ecliptic
22h 0m
21h 20m
20h 40m
Sidereal Time = Right Ascension + Hour Angle
Saturn: 21h 59m RA +
(- 0h 16m) HA = 21h 43m ST
Uranus: 19h 22m RA + 2h 21m HA = 21h 43m ST
20h 0m
19h 20m
Hour Angle
- 0h 16m
Saturn
RA = 21h 59m
Hour Angle
Uranus
RA = 19h 22m
1:50 am MDT 20 August 1993
SOLAR VERSUS SIDEREAL TIME
Hour Angle of
Sidereal Time
= 21 hrs 43 min
23h 20m
Vernal Equinox
= -2h17m
= 21h 43m
= Sidereal Time
Every year the Earth actually makes 366 1/4 complete rotations with respect to the stars (sidereal days). Each day the Earth also revolves about 1° about the Sun, so that after one year, it has "unwound" one of those rotations with respect to the Sun; on the average, we observe 365 1/4 solar passages across the meridian (solar days) in a year. Since both sidereal and solar time use 24­hour days, the two clocks must run at different rates. The following compares (approximate) time measures in each system:
SOLAR
365.25 days 1 day 0.99727 d
SIDEREAL
366.25 days 1.00274 d
1 day
SOLAR
24 hours 23h 56m 4s 6 minutes
SIDEREAL
24h 3m 56s 24 hours 6m 1s
The difference between solar and sidereal time is one way of expressing the fact that we observe different stars in the evening sky during the course of a year. The easiest way to predict what the sky will look like (i.e., determine the sidereal time) at a given date and time is to use a planisphere, or star wheel. However, it is possible to estimate the sidereal time to within a half­hour or so with just a little mental arithmetic.
At noontime on the date of the vernal equinox, the solar time is 12h (since we begin our solar day at midnight) while the sidereal time is 0h (since the Sun is at 0h RA, and is on our meridian). Hence, the two clocks are exactly 12 hours out of synchronization (for the moment, we will ignore the complication of "daylight savings"). Six months later, on the date of the autumnal equinox (about September 22) the two clocks will agree exactly for a brief instant before beginning to drift apart, with sidereal time gaining about 1 second every six minutes.
+ 2h 21m


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For every month since the last fall equinox, sidereal time gains 2 hours over solar time. We simply count the number of elapsed months, multiply by 2, and add the time to our watch (converting to a 24­hour system as needed). If daylight savings time is in effect, we subtract 1 hour from the result to get the sidereal time.
For example, suppose we wish to estimate the sidereal time at 10:50 p.m. Mountain Daylight Time on August the 19th. About 11 months have elapsed since fall began, so sidereal time is ahead of standard solar time by 22 hours ­ or 21 hours ahead of daylight savings time. Equivalently, we can say that sidereal time lags behind daylight time by 3 hours. 10:50 p.m. on our watch is 22h 50 m on a 24­hour clock, so the sidereal time is 3 hours less: ST = 19h 50m (approximately).
ENVISIONING THE CELESTIAL SPHERE
With time and practice, you will begin to "see" the imaginary grid lines of the alt­azimuth and equatorial coordinate systems in the sky. Such an ability is very useful in planning observing sessions and in understanding the apparent motions of the sky. To help you in this quest, we’ve included four scenes of the celestial sphere showing both alt­azimuth and equatorial coordinates. Each view is from the same location (Boulder) and at the same time and date used above (10:50 p.m. MDT on August 19th, 1993). As we comment on each, we'll mention some important relationships between the coordinate systems and the observer's latitude.
Looking North
From Boulder, the altitude of the north celestial pole directly above the North cardinal point is 40°, exactly equal to Boulder's latitude. This is true for all observing locations:
Altitude of the pole = Latitude of observer
The +50° declination circle just touches our northern horizon. Any star more northerly than this will be circumpolar ­ that is, it will never set below the horizon.
Declination of northern circumpolar stars > 90° ­ Latitude
Most of the Big Dipper is circumpolar. The two pointer stars of the dipper are useful in finding Polaris, which lies only about 1/2° from the north celestial pole. Because these two stars always point towards the pole, they must both lie approximately on the same hour circle, or equivalently, both must have approximately the same right ascension (11 hours RA).


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Looking South
If you were standing at the north pole, the celestial equator would coincide with your local horizon. As you travel the 50° southward to Boulder, the celestial equator will appear to tilt up by an identical angle; that is, the altitude of the celestial equator above the South cardinal point is 50° from the latitude of Boulder. Your local meridian is the line passing directly overhead from the north to south celestial poles, and hence coincides with 180° azimuth. Generally speaking, then,
Altitude of the intersection of the celestial equator with the meridian = 90° ­ Latitude
Since the celestial equator is 50° above our southern horizon, any star with a declination less than ­50° is circumpolar around the south pole, and will never be seen from Boulder.
Declination of southern circumpolar stars < Latitude ­ 90°
The sidereal time (right ascension on the meridian) is 19h 43m ­ only 7 minutes different from our estimate.
Looking East
The celestial equator meets the observer's local horizon exactly at an azimuth of 90°; this is always true, regardless of the observer's latitude:
The celestial equator always intersects the east and west cardinal points


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At the intersection point, the celestial equator makes an angle of 50° with the local horizon; in general,
The intersection angle between celestial equator and horizon = 90° ­ Latitude
Our view of the eastern horizon at this particular time includes the Great Square of Pegasus, which is useful for locating the point of the vernal equinox. The two easternmost stars of the Great Square both lie on approximately 0 hours of right ascension. The vernal equinox lies in the constellation of Pisces about 15° south of the Square.
Looking Up
From a latitude of 40°, an object with a declination of +40° will, at some point in time during the day or night, pass directly overhead through the zenith. In general
Declination at zenith = Latitude of observer
The 24 Ephemeris Stars in the SBO Catalog of Astronomical Objects have Object Numbers ranging from #401 to #424. Each of these moderately­bright stars passes near the zenith (within 10° or so) over the course of 24 hours. At any time, the ephemeris star nearest the zenith will usually be the star whose last two digits equals the sidereal time (rounded to the nearest hour). For example, at the current sidereal time (19h 43m), the zenith ephemeris star is #420 ( Cygni).
At the time of the year assumed in this example (late summer), and at this time of night (mid­evening), the three prominent stars of the Summer Triangle are high in the sky: Vega (in Lyra the lyre), Deneb (at the tail of Cygnus the swan), and Altair (in Aquila the eagle). However, the Summer Triangle is not only high in the sky in summer, but at any period during the year when the sidereal time equals roughly 20 hours: just after sunset in October, just before sunrise in May, and even around noontime in January (though it won't be visible because of the Sun).


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Telescope Types
Telescopes & Observing
Telescopes come in two basic types ­ the refractor, which uses a lens as its primary or objective optical element, and the reflector, which uses a mirror. In either case, light originating from an object (usually at infinity) is brought to a focus within the telescope to form an image of the object. The size of a telescope refers to the diameter its primary lens or mirror, rather than its length.
By placing photographic film at the focal plane, the objective lens or mirror forms a camera system. If instead we position an eyepiece lens at an appropriate distance behind the focal plane, we form an optical telescope.
The optical arrangement of a refracting telescope is shown below. The image is formed by the refraction of light through the lens. The refractor has an advantage over reflectors in that there is no central obscuration to produce diffraction patterns, and therefore yields crisper images. However, refraction introduces chromatic aberration, which is corrected by using two­element (doublet or achromat) or three­element (apochromat) lenses. The lens complexity makes the refractor very expensive; hence, refractors are much smaller in diameter than comparably­priced reflectors. All of the Sommers­Bausch Observatory (SBO) finder telescopes are of the refractor type.
Objective Lens
Light from Object at Infinity
Eyepiece Lens
Eye
Focal Plane
A reflecting telescope focuses and redirects light back towards the incident direction, and therefore requires additional optics to get the image "out of the way". This central obscuration reduces the amount of light reaching the primary, and adds diffraction patterns that degrade the resolution. However, the telescope does not suffer from chromatic aberration, since only mirrors are used. Reflectors can be built much larger since the mirror is supported from behind (while a lens is mounted only at its edges). Furthermore, only one objective surface must be ground and polished, making the reflector much less expensive. As a result, virtually all large telescopes are of the reflector type.
The Newtonian (invented by Sir Isaac Newton) is the simplest form of reflector. It uses a diagonal mirror (a plane mirror tilted at a 45° angle) to re­direct the light out the side of the telescope to the eyepiece. The placement of the eyepiece at the "wrong" end of the telescope limits it practical size, and its asymmetric design precludes the use of heavy instrumentation. The Newtonian is used primarily by amateur astronomers since it is the "cleanest" as well as least expensive reflector.


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Light from Object at Infinity
Diagonal Mirror
Prime Focal Plane
Primary Mirror
Eyepiece Eye
In the Cassegrain reflector, a convex secondary mirror intercepts the light from the primary and reflects it back again, reducing the convergence angle in the process. The light passes through a central hole in the primary and comes to a focus at the back of the telescope. The location of the Cassegrain focus makes it easy to mount instrumentation, and the folded optical design permits larger diameter telescopes to be houses within smaller domes; hence this design is most widely­used at professional observatories. All three of the permanently­mounted SBO telescopes (16", 18", 24") are Cassegrain reflectors.
Eyepiece
Light from Object at Infinity
Eye
Prime Focus (not used)
Secondary Mirror
Primary Mirror
Telescopes that use a combination of lenses and mirrors to form images are called catadioptric. One form is the Schmidt camera, which uses a weak lens­like corrector plate at the entrance to the telescope to correct for off­axis image aberrations; this specialized telescope can't be used for viewing but does produce panoramic sky photographs. SBO has an 8" Schmidt for astrophotography.
Light from Object at Infinity
Corrector Lens
Focal Plane Film
Concave Mirror
One of the most popular, albeit expensive, telescope designs is the Schmidt­Cassegrain. As the name suggests, it looks like the Cassegrain telescope but with the addition of a Schmidt corrector plate. SBO has seven of these smaller, portable telescopes: an 8" Meade, two 5" Celestrons, two 5" Meades, and two 3.5" Questars.


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The fundamental optical properties of any telescope are described by three parameters: the focal length, the aperture, and the focal ratio (f/ratio). The focal length (f) is the distance from the objective where the image of an infinitely­distant object is formed. The aperture (A) of a telescope is simply the diameter of its light­collecting lens (or mirror). The f/ratio is defined to be the ratio of the focal length of the lens or mirror to its aperture:
f/ratio =f/A . (1)
Obviously, if you know any two of the three fundamental parameters, you can calculate the third.
Focal Length
As shown in the diagram below, an object that subtends an angular size  in the sky will form an image
of linear size h given by tan() = h/f. Therefore
h = radians f =  f . (2)
Object
at
Infinity
Parallel
Incident
Rays
θ
Image at Focal Plane
f θh
The image scale is the ratio of linear image size to its actual angular size:
Image Scale = h/ = f/ . (3)
Thus, the scale of the image of any object depends only upon the focal length of the telescope, not on any other property: two telescopes with identical focal lengths will produce identically­ sized images of the same object, regardless of any other physical differences. Furthermore, the image scale is directly proportional to f: doubling the focal length will produce an image twice the linear size (and four times the area).
The plate scale (used in photography) is usually expressed as the inverse of the above ­ the angular size of the object (usually in arc­seconds) corresponding to a linear size (usually in millimeters) in the focal plane.
For a compound telescope (with more than one active optical element), we refer to the effective focal length (EFL) of the entire optical system, and treat it as a simple telescope with single lens or mirror of focal length f = EFL.


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Aperture
The aperture A of a telescope is the diameter of the principle light­gathering optical element. The light­ gathering ability, or light grasp, of the telescope is proportional to the area of the objective element, or
A2. For point sources such as stars, all of the collected light will (to a first approximation) converge to form a point­like image; hence, stars appear brighter, and fainter stars can be detected, with telescopes of larger aperture. Telescope aperture is the principle criteria for determining the limiting visible stellar magnitude.
The resolving power (ability to resolve adjacent features in an image) of an optical telescope is also chiefly a function of aperture; the larger the aperture, the smaller the diffraction pattern formed by each point source, and therefore the better the resolution. The theoretical diffraction­limited resolution of a telescope is given by
diff  1.2/A  5 arc­sec/Inches of Aperture (4) where  is the wavelength of the light used, assumed to be 5500 Å.
Focal Ratio
Although the amount of light gathered by a telescope is proportional to A2, the collected light is spread
out over an area at the focal plane that is proportional to h2, and therefore proportional to f2; hence, the
image brightness of an extended (not point­like) object will scale linearly with the ratio (A/f)2, or inversely with the square of the f/ratio = f/A of the telescope:
Brightness  1 / (f/ratio2) . (5)
The f/ratio of a telescope is therefore the only factor that determines the image brightness of an extended object. For example, if one telescope has twice the aperture and twice the focal length of another, both telescopes are geometrically similar and would use exactly the same photographic exposure to produce identically­bright images of, say, the Moon. Of course, the first telescope would produce an image twice the linear size (and four times the area) as the latter, but both would have the same photographic "speed". Note that the smaller the f/ratio, the brighter the image and the faster the speed: a 35mm camera using an f/ratio of f/2 will photograph the Milky Way in less than 5 minutes, while the same film on an f/15 telescope will require an hour or more to capture the diffuse glow! On the other hand, individual stars will record much better using the telescope.
The optical speed of a compound telescope is simply the ratio of its effective focal length to its aperture. Both effective or actual f/ratios are a measure of the final angle of convergence angle of the cone of light before it forms the image; the smaller the f/ratio, the greater the convergence, and the more critical the focus; this is why "slow" optics, with a slowly­converging beam, exhibit a larger "depth­of­field".


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Seeing and Clarity
Equation (4) gives the theoretical limit to the angular size that can be resolved by a telescope. This limit is almost never achieved in practice, since atmospheric turbulence is always present to blur our image of the object. The quality of the seeing is measured by the angular separation needed between two stars for their images to just be resolved. Average seeing in the Boulder area is about 2 arc­seconds, making it a marginal task to "split" the 2 arc­sec pairs of the "double­double" star Epsilon Lyrae. Good seeing in Boulder is when the atmosphere is stable enough to resolve 1" separations. Poor seeing conditions can be as bad as 5" or even worse. By comparison, half­arc­second seeing occurs routinely at several carefully located major observatories, but it is rare for any ground­based telescope to experience 0.2" conditions.
One can estimate the seeing of a night simply by glancing up. If the stars glow solidly, the seeing is probably "good"; if they twinkle, the seeing is "average"; if bright stars dance and planets flash with color, the seeing is "poor". Another measure is to look towards Denver ­ if there are lots of particulates in the air, and Denver is on smog alert, you will see a bright horizon glow; in this situation, you can usually count on good seeing! These conditions are created by an inversion layer of stagnant air, which permits rock­solid astronomical viewing.
The best conditions for good seeing are the worst for sky clarity. Good clarity implies dark skies due to a lack of light­scattering dust particles, and an absence of water­vapor haze. Clarity usually improves in Boulder after the passage of a thunderstorm, which clears out the dust. Of course, the conditions that improve clarity usually destroy seeing.
Since ideal nights of good clarity and seeing are rare, an observer must be prepared to take advantage of the best properties of the night, if any. Lunar and planetary observing requires good seeing conditions, since planetary disks are small, only 2­40 arc­seconds in diameter. Poor clarity is not a major problem for bright solar system objects, although low­contrast features may be washed out. On the other hand, good clarity (and the absence of strong moonlight) is essential to observe galaxies and diffuse nebulae, since the light from these objects is faint and dark skies are needed for contrast. Seeing is not critical, since these objects are fuzzy patches to begin with. When both seeing and clarity are poor, it's best to focus your attention on bright star clusters and widely­spaced double stars.
Eyepieces and Magnification
An eyepiece or ocular is simply a magnifier that allows you to inspect the image formed by the objective from a very short distance away. The eyepiece is placed so that its focal plane coincides with the focal plane of the objective, so that the rays from the image emerge parallel from the eyepiece. As a result, the telescope never forms a final image ­ the lens of your eye does that.


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By selecting appropriate rays for both the objective lens (obj) and the eyepiece lens (eye), we can see that rays incident at the telescope at an angle obj will emerge from the eyepiece at a larger angle eye; the
observer perceives that the object subtends a much larger angle than is actually the case. A little geometry gives the angular magnification M produced by the arrangement:
M eye / obj  obj / eye . (6)
That is, magnification is the ratio of the objective focal length divided by the eyepiece focal length. For example, the 16­inch f/12 telescope has a focal length of 192 inches, or 4877 mm. If we use an eyepiece with a focal length of 45 mm (engraved on its barrel), the "power" of the telescope will be about 108 X; by switching to an 18 mm eyepiece, we will have 271 X. The answer to the question "what is the power of this telescope?" is "whatever you want ­ within the range of the available eyepiece assortment".
Eyepieces come in a variety of designs, each representing a different trade­off between performance and cost, ranging from the inexpensive short­focal­length two­element Ramsden (R) to the 6­element triple­ doublet Erfle (Er). Other types include: the Kellner (K), an improved Ramsden; orthoscopic (Or), good at moderate focal lengths at reasonable cost; and the expensive low­power wide­field designs ­ the Plossl (including Clave), the Konig, and the Televue.
Besides focal length (and image quality), the other important characteristic of an eyepiece is its field­of­ view ­ the size of the solid angle viewable through the ocular, or when used on a particular telescope, the actual angular size of the observable sky field. The field available with a given telescope­eyepiece combination can be measured directly by positioning a bright star just at the northern edge of the field; after noting the declination, you move the telescope northward until the star is at the southern boundary of the field, note the declination again, and calculate the difference in angle. The field can also be calculated from the image scale of the telescope (equation (3)): measure the diameter of the field stop (the ring installed within the open end of the eyepiece) , equate that to the linear image size h, and calculate the corresponding angle .
The Barlow is a telecompressor (concave or negative) lens that can be installed in front of the eyepiece. It reduces the angle of convergence of the objective light cone and hence increases the f/ratio and the EFL of the telescope, thus increasing the magnification (by a factor of 2 to 3) from a given eyepiece. It helps achieve high magnification without sacrificing eye relief (see below).


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Selecting an Eyepiece
The choice of eyepiece is one of the few factors that an observer may control to enhance the visibility of astronomical objects.
The Observatory's eyepieces range from focal lengths of 70 mm down to 4 mm. The longer focal lengths are in the 2"­diameter format, which fit directly into the large telescope tubes; the shorter (higher magnification) eyepieces have 1­1/4" diameter barrels, but can be used in the 2" tube using an eyepiece adapter plug.
Although equation (6) implies that it's possible to have any magnification one desires, there are practical limits. The entrance pupil of the human eye (the diameter of the iris opening) is about 7 mm for a fully dark­adapted eye (5 mm for older individuals). The exit pupil of an telescope (diameter of the bundle of light rays exiting the eyepiece) can be shown to be
Exit Pupil = A / M = feye / (f/ratio) (7)
If the exit pupil is larger than the entrance pupil of the eye, the eye can't intercept it all and some of the light is wasted. This occurs if the magnification is too low. If the exit pupil just matches the eye pupil, all of the light is utilized and we have the brightest­possible, or "richest­field" arrangement. This is why 7x50 (7 power, 50 mm aperture) and 11x80 (11 power, 80 mm aperture) binoculars are excellent for night observing ­ their exit pupils optimally match the dark­adapted human eye. At higher magnifications, all of the light enters the eye but is spread over a larger solid angle, dimming the field.
The average human eye can just barely resolve two objects separated by about 1 arc­minute, although a separation of about 4' (240") is much more comfortably perceived (about 50 such 4 arc­minute "pixels" comprise the face of "the man in the Moon"). Hence, one criterion for a telescope's maximum useful power Mmax is "that magnification that matches a 250 arc­second visual separation to the diffraction
limit of the telescope"; from equation (4) this equates to
Mmax  50 x Aperture of Telescope in Inches (8)
By this "rule of thumb", the 16­inch telescope has a maximum useful magnification of 800 X on a night of perfect seeing, which would be achieved with a 6 mm eyepiece. Any greater magnification will be "empty" ­ that is, the image will become larger, but the enlargement will contain only "blur", not additional detail. (Note: poor­quality 2.4"­refractors are provided with 4 mm eyepieces plus a cheap 2.5X Barlow lens so that the manufacturer can advertise "600 power" ­ 5 times beyond any useful application!)
The above magnification limit is somewhat optimistic for telescopes of moderate­to­large aperture, since detail is almost invariably limited by atmospheric seeing rather than by telescope resolution. For example, if the seeing is about 1", a 250" perceived separation implies a useful maximum magnification of about 250 X ­ or an eyepiece in the 18 ­ 24 mm range for the 16­inch telescope. For 2" seeing, a reasonable choice is about 125 power, or eyepieces in the 32 ­ 45 mm range.
There are several additional considerations related to high magnification. On the negative side, short­ focal­length eyepieces require critical focussing and eye placement, making them difficult for inexperienced observers to use. In addition, they exhibit short eye relief ­ the distance behind the lens


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where the eye is positioned to see the entire field­of­view. In particular, eyepieces shorter than about 12 mm focal length are problematic for eye­glass wearers, since glasses prevent the eye from being placed close enough to avoid "tunnel vision".
On the positive side, high magnification reveals fainter stars. Remember that stars are unresolved point sources whose light is concentrated (to a first approximation) at a single point in the image regardless of magnification. The glow of the background sky is a diffuse source, which will be spread out by higher magnification, reducing its brightness. Although high magnification doesn't increase the brightness of faint stars, it improves their contrast against the sky, making them more visible! By this same token, high magnification helps diminish the intense glare from bright solar system objects, making the Moon less painful to look at, and the bands of Jupiter easier to see.
Finally, there is the consideration of the type and angular extent of the object being viewed. High magnification certainly helps resolve fine planetary detail and separates close double stars, provided that seeing conditions permit. Open clusters usually extend over a large patch of the sky, and hence need low power (a wide field­of­view) to encompass them ­ in fact, the small finder scopes may present a more pleasing view than the main telescope. High power won't help the contrast between sky background and diffuse nebulae (since both are extended sources), and in fact may keep the observer from seeing the glow since all aspects of the image are dimmer. Low power is essential for extremely large nebulae, since these objects can fill the field­of­view ­ creating a situation where "you can't see the forest for the trees". Globular clusters can be appreciated at a variety of magnifications: low power creates an impression of a "cotton­ball" floating in space, while high magnification shows a magnificent sparkling array of bright points reminiscent of distant city lights. In the end, your personal experience and judgement should be your guide.
Observing Technique
Observing through an eyepiece is an unnatural experience; good observing techniques come with time and experience. Here are some hints to help you get the most out of your telescope time:
• Let your eyes become fully dark­adapted before doing "serious" observing. This can take 20­ 30 minutes.
• Keep both eyes open; this will help you relax your eyes to infinity focus.
• "Gaze", don't "glimpse". It takes a few moments to mentally and optically adjust to the scene in an eyepiece. Continued observation also improves the chances for brief periods of atmospheric stability when new details may appear.
• Don't stare fixedly through the eyepiece; let your eye wander. The human eye is much more sensitive to changes in brightness than to constant light levels. By looking around, you'll see fainter detail.
• Use averted vision to help bring out dim features. The color­sensitive cone cells concentrated near the center of the eye's retina don't respond to low light levels. If you look out of the "corner of your eye", you'll utilize the much more sensitive black­and­white rod cell receptors that are used for peripheral vision.
• Finally, don't expect to see the colors that appear in photographs; for the reason just mentioned, most faint objects appear greenish to whitish because they are too faint to stimulate the color receptors in your eye.


Sommers­Bausch Observatory 45
Solar Observing at SBO
The heliostat (solar telescope) on the deck of Sommers­Bausch Observatory is used to bring an image of the Sun directly into the laboratory. This is one of the few facilities in the country that permits students to continuously monitor real­time solar activity ­ without ever having to leave their seats! Detailed information about the heliostat, and the various ways it can observe the Sun, can be found at the Sommers­Bausch Observatory website:
sbo.colorado.edu/telescopes/heliostat/heliostat.html
The instrument is used in portions of several different ASTR 1010 and ASTR 1030 laboratory exercises: to keep track of the changing distance of the Earth from the Sun (Seasons); to determine the temperature of sunspots (Temperature of the Sun); and to look at the spectrum of light coming from our star (Spectroscopy).
However, the heliostat can be used for much, much more ... but unfortunately, solar activity is somewhat unpredictable ... as is, of course, the local weather. It is difficult to design and plan laboratory exercises around a star and a planet that may not cooperate on a particular day.
As a result, we're going to take the approach that "if something really interesting is happening, we'll stop whatever we're doing and take a look". The following pages will help guide you through some of the interesting possibilities.
Sketching Sunspots
The "Large White Light" heliostat mode projects an image of the solar photosphere onto the laboratory wall, making it easy to see and study details in the solar photosphere. The most prominent features you'll see, of course, are the dark areas known as sunspots.
It's easy to sketch details of sunspots ­ simply hold a sheet of white paper against the wall and directly trace, with a pencil, all of the details of the spot that you can see. Be sure to appropriately shade the dark central umbra of the spots, and the surrounding lighter penumbra regions. You might also wish to add a scale to your drawing ... at this projection, each millimeter corresponds approximately to 1,100 miles on the "surface" of the Sun!
Note that spots tend to appear in sunspot groups. Some of the bigger, complex, and more "gnarly­ looking" of these regions are the most likely to be active regions giving rise to flares and other interesting features in the overlying solar chromosphere and corona.
WARNING: The intense solar light from the heliostat can cause instant eye damage! Do NOT look back up the beam of sunlight!


Sommers­Bausch Observatory 46
Sunsets
An enjoyable pastime is to watch a sunset behind Green Mountain, three miles to the west, using the Large White Light mode of the heliostat. We can observe sunsets daily at high magnification from September through March, weather permitting. Each evening's sunset is unique as the Sun disappears behind different trees or rocky crags of the foothills.
The actual time of sunset depends on a number of factors: the date (which sets the declination of the Sun); the shape of the mountain profile as seen from the Observatory; the "equation of time" which records whether the Sun is running "fast" or "slow" compared to our watches; and of course, daylight savings time.
Sunsets can occur as early as 3:20 p.m. in November and December, as the Sun reaches its lowest declination and passes behind the peak of Green Mountain ... or as late as 6:30 Daylight Savings Time in September, when it sets behind Flagstaff Mountain instead.
So that you can plan ahead, the heliostat manual includes a timetable of when and where a sunset will occur for any day of the year.
Sunspot Temperatures
The Sun radiates energy in accordance with the Stefan­Boltzmann Law, which states that the intensity I (power emitted per unit area of the radiating body) is proportional to the fourth power of the temperature
T (in Kelvin). For example, if the Sun's temperature were to suddenly double, it would emit 24 = 16 times as much energy as before!
Obviously, then, if a region of the Sun appears darker than its surroundings ­ like a sunspot ­ we can infer that the area is "cooler" than the rest of the Sun (relatively speaking, of course!).
The Stefan­Boltzmann Law gives us a quantitative way to measure the relative temperatures of the Sun from the observed intensity of the light coming from it:
⎛I
T = T ⎜ spot ⎟
⎞ 1/4 spot sun ⎝Isun ⎠
To measure the temperature of a spot, use the Observatory's pinhole lightmeter to measure the intensity Ispot of the light coming from a sunspot, and also the intensity Isun from the brighter surrounding region. Substitute these measurements into the equation, and use the average overall temperature of the Sun, 5800 K, for the value of Tsun. You'll find that sunspots are, in fact, anything but "cool"!


Sommers­Bausch Observatory 47
Sunspot Latitude and Longitude
The "Small White Light" mode of the heliostat permits you to map the location of sunspots. Position a sunspot record form in the holder so that the Sun's image is centered on the circle. Carefully trace with a pencil all of the sunspots that are visible.
North is not necessarily at the top of the image. You determine direction by noting which way the image shifts when the heliostat is driven in a known direction: without disturbing your drawing, drive the heliostat briefly in the west direction, using the direction toggle on the heliostat control box. Since the field of view is now westward of its original position, the solar image appears to have shifted to the east.
Follow the motion of a single sunspot. When the spot clears the disk circle, make an "X" at its new position and label it "earth east".
Next, map out the directions from Earth's point of view. Draw a line from the original position of the selected sunspot to its final location. This line is parallel to the Earth's equator. Use a protractor to draw a second line perpendicular (90°) to the equatorial line and through the center of the solar disk. The new line marks the projection of the Earth's axis of rotation onto the disk of the Sun. Label the upper end of the line Nearth (for
"Earth north") and the lower end Searth (for "Earth south").
The Earth's and the Sun's axes of rotation are not aligned with each other: the Earth's north pole is aimed approximately towards the star Polaris in Ursa Minor, while the Sun's north pole is oriented about 26° away
towards the star Delta Draconis. As a result, when we view the Sun from the Earth at different times during the year, the Sun's north pole may appear tilted eastward or westward of the Earth's north pole, and may be tipped either towards or away from us as well.
The number of angular degrees of tilt and tip are defined by two angles, P and Bo; these values
can be found in the Astronomical Almanac for the current day.
The angle P describes how much the north pole Earth of the Sun is tilted, in the plane of the sky (or the East plane of your paper), towards the east (or west)
from Earth north. A positive angle P means the
Sun's north pole lies to the east of Nearth.
Nsun
P
Earth North
+-
Looking towards the Sun from the Earth
Earth West
Sun
Plane of sky
and drawing paper
Earth South
Ssun


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The angle Bo describes how much the north pole of the Sun is tipped towards (or away from) you, the observer on Earth. A positive angle Bo means that the north pole of the Sun is tipped towards the Earth (so that the north pole of the Sun would, at least theoretically, appear on your drawing).
Bo
- + Nsun
Sun
S sun
Looking sideways at the Sun and Earth
Earth North
Earth
Earth South
Use a protractor to draw a line through the center of the solar image at an angle P from the Nearth­Searth
line; remember, the line should lie to the east (left) of Earth north if P is positive, and to the west (right) if negative. This line marks the solar meridian, the north­south line dividing our view of the Sun into eastern and western hemispheres. Mark the upper end of the solar meridian Nsun (solar north) and the lower end Ssun (solar south).
A transparent overlay, known as a Stonyhurst disk, will help you find the latitude and longitude of the sunspots. The grid is marked every 10° in latitude north and south of the solar equator, and every 10° east or west of the solar meridian line. Choose the Stonyhurst overlay with a Bo closest to the actual value corresponding to your observation. Center the circle of the overlay on top of your circular drawing, with the axis aligned with the solar meridian. Be sure that the correct sign (+ or ­) for Bo appears at the top of the overlay.
Finally, number the prominent sunspots and estimate, to the nearest degree, the solar latitude (N or S of the solar equator) and solar longitude (E or W of the solar meridian) of every numbered spot.
The Sunspot Cycle
The number of sunspots is observed to grow and decline over a period of approximately 11 years; this phenomenon is known as the sunspot cycle.
At the beginning of a new 11­ year cycle, sunspots first appear at high latitudes (approximately 40° north and south of the solar equator). As the cycle progresses, the average latitude of the sunspots shifts to lower latitudes, so that near the end of the cycle the majority of the sunspots appear around 10° north or south of the equator.
+40 +30 +20 +10
0 -10 -20 -30 -40
DATE
200 150 100
50 0
Plane of sky and drawing paper
1920 1930 1940 1950 1960 1970 1980


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The upper chart shows the latitudes at which sunspots have occurred over the past 80 years. Although spots can appear at nearly any latitude, note the trend from high to low latitudes in each cycle. The pattern of the distribution has given the chart its name: the butterfly diagram.
The lower chart shows the annual average sunspot number; it clearly illustrates the cyclical nature of solar activity. The number is computed as follows:
{(Number of Spots) + (Number of Groups x 10)} x Correction Factor = Sunspot Number
Count every visible spot, including each tiny individual spot as well as those appearing in groups. To this is added the number of distinct sunspot groups, which count as an additional 10 spots each. The sum is then multiplied by a correction factor (we use a value of 2.0) which takes into account the size of the solar telescope, the location, and the experience of the observer.
You can compare your determination of the sunspot number with the official daily count found at
www.sunspotcycle.com/
It is frequently possible to get a rough estimate of the current phase of the sunspot cycle from a single day's observation. Simply compare your sunspot count with the chart above, and figure in the average latitude of the spots to deduce whether we're in the early or late stages of the current 11­year cycle.
Solar Rotation
Sunspots are observed to shift their positions across the solar disk due to the rotation of the Sun. By using two separate latitude/longitude sunspot drawings made from one or more days apart, you can measure the solar rotation rate.
Identify one or more spots that are common to both drawings. Appearance, relative position to other spots, and the measured latitude are all clues in making the identifications.
Use the difference in the measurements of spot longitude to determine the size of the angle through which the spot has rotated. Divide the observed
rotation angle by the elapsed time in fractional days
to determine the apparent solar rotation rate in
degrees per day.
Your measurement was made from a moving platform: the Earth, which orbits around the Sun at a rate of 360° in one year (365 days), or an average motion of almost exactly 1° per day. (This is probably not a coincidence; it is generally assumed that ancient astronomers/mathematicians divided the circle into 360 parts for just this reason!)
We orbit the Sun in the same direction that it rotates so that our motion "chases after" the sunspots. Therefore, the apparent movement of spots is less than their actual rotation by about 1° per day. You'll need to compensate for the orbital motion of the Earth by adding 1° to your computed apparent daily rotation to get the Sun's true rate of rotation.


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Photosphere (White­Light Image)
The photosphere (literally, "sphere of light") is the visible layer of the solar atmosphere, about 500 km (300 miles) thick, from which we receive most of the Sun's light. This layer of the Sun may be observed either using the "Large White Light" mode of the heliostat, or with the SCRIBES camera imaging system.
The most prominent features are sunspots (with the dark umbra and surrounding semi­dark penumbra regions). You may also notice the brightness mottling (called faculae) that occurs over the entire disk. And on an exceptionally good day you can just pick out granulation cells (convection cells about 1000 km (600 miles) across, similar in nature to earthly cumulus clouds) which deliver thermal energy from the solar interior to the photosphere.
Lower Chromosphere (Calcium­K Filter)
The region of the solar atmosphere about 500 km (300 miles) above the photosphere can be observed using the ultraviolet light emitted by calcium atoms present in the Sun; a calcium­K filter and SCRIBES camera system is used to make this layer visible.
Look for the bright patches, called plages ("PLA­juhs") that tend to surround sunspots. These regions delineate the "active region" where the magnetic fields associated with sunspots are the strongest. Essentially, these bright regions mark the strength, location, and extent of strong solar magnetic fields ­ and prove that seemingly isolated sunspots are actually just pieces of a much larger, complex, and dynamic grouping. Far away from the spots, look for large, ill­defined circlets of bright emission, which are the boundaries of super­granulation convection cells. These regions are thought to deliver energy from very deep in the solar interior up to the surface.
Upper Chromosphere (Hydrogen­alpha Filter)
Several thousand kilometers above the photosphere (and sometimes extending outward to several tens of thousands of kilometers) is the chromosphere, or “sphere of color”. The layer is named for the pink light (a combination of red and blue) emitted from this layer by hydrogen gas. The chromosphere is a thousand times dimmer than the photosphere, but can be observed on any clear day using a special hydrogen­alpha (Ha) filter. The filter permits you to see only the red light emitted at a wavelength of 6563 Ångstroms by hydrogen atoms in the solar atmosphere.