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Small Telescopes, Big Science
Arne Henden
Director, AAVSO
arne@aavso.org
The “big” telescope era
-1970’s
- 4m to 5m class
- public access
- expensive
- manual operation
Courtesy NOAO
Current Status-15+ 8m-class telescopes
-number of specialty telescopes (VISTA, PanSTARRS)
- oversubscribed
Gemini N (NOAO)
VLT (ESO)
Professional Directions
- bigger aperture
- expensive instrumentation
- Chilean location
- expensive operations
- funding? $1,000,000,000 each!
Courtesy Magellan, TMT, ESO
The Opposite Extreme
Courtesy XO, Stare, ASAS
- small apertures, often camera lenses
- wide field, bright stars
- inexpensive
- automated
Science that requires aperture
• Cosmology (dark energy, dark matter, supernovae at Z=2)
• Time resolution on faint objects
• Spectroscopy, especially hi-res
• Adaptive optics
• Infrared observations (flux and weight)
Large Telescope
Instruments
Phoenix
GNIRS
Phoenix
Aperture advantages
• Increased payload capacity
• Increased instrumentation budget
• Good operations support
• Pristine site development
Paranal
Aperture drawbacks
• Expensive
• Site consolidation (Chile!)
• Limited access
• Change of parameter space
• Less funding for smaller telescopes
Small Telescopes?
2-6m = “small”
Worried about closing down these facilities
Expensive to run (often old)
True “Small Telescope” (60cm or less) Advantages
• Inexpensive
• Dedicated
• Can be located anywhere in the world
• Work fine for bright objects
• Can be high cadence (seconds)
• Quality commercial equipment
• Easy to automate
Commercial components
STL (SBIG)
LX-200 (Meade)Prodome
Small Telescope Disadvantages
• You break it, you fix it
• Seldom at pristine site (precious)
• You can’t go cheap
• Details of hardware proprietary
• Small instrument carrying capacity
• Few vendors at the 60cm+ scale
Sonoita Research Observatory
35cm robotic telescope
Used 300 nights/year
Southern Arizona
USD$40000
Ellijay facilities
Small Telescope Alternative
• Refurbish existing telescope
• Established site
• Usually maintenance is available
• Need hardware expertise
• Use commercial products where possible; standard software drivers
Mt. John University Observatory-43d59.2m south, 170d27.9m east, 1031m elevation
Optical Craftsman 60cm
MJUO Optical
Craftsman61cm
Installed in 1970
Refurbished 1979
Computerized 1991
F/16
Lowell/Morgan Telescope
Built in 1960’s by Tinsley; 60cm f/13 Classical Cassegrain
Donated to Lowell Observatory
Used for photographic planetary patrol 1970-1990
Used for CCD observing and personal research in 1990’s
Placed in Steele Visitor Center
Donated to AAVSO 2008
Refurbishment and siting at Dark Ridge Observatory, NM
Will be used for automated photometry, spectroscopy, large instruments
Dark Ridge View
Small Telescope Science
• Lucky imaging
• Asteroids
• Exoplanets
• Variable Stars
Lucky ImagingSmall apertures match Fried parameter
Commercial video cameras have good resolution, subsec exposure capability
Software to register and sift through images available
Russell Hawker; 12-inch
AsteroidsDiscovery space limited; funded surveys like LINEAR, CSS, LONEOS
Many opportunities for light curves
Target of Opportunity, esp. NEO, PHA Courtesy B. Warner
(2008tc3 movie, Nazaret)
ExoplanetsMore than 300 known
About 50 are transiting
Need wide-field system for discovery
Kepler, CoRoT
Follow-up easy, but time consuming
Keck
QuickTime™ and aMPEG-4 Video decompressor
are needed to see this picture.
Fomalhaut NASA
XO
Mercury transit micromag
Exoplanet transits
Vanmunster
0.02mag, 35cm
Discovered by 10cm telescopes
Tonny VanmunsterBelgium2x35cm, CCDCVs, exoplanets
Cindy Foote
Scopecraft 24” and 16”
30 second exposures, Rc
6mmag
Variable Stars
• Every star varies during its lifetime• Physical variation (pulsation, spots) tell us
about stellar structure, cosmology• Geometrical variation (binaries) give us
masses, densities, sizes• Accretion disk phenomena prevalent at all
scales• Transient events (novae, supernovae,
gamma-ray bursts) detail stellar evolution• If you are an astronomer, you will study
variable stars sometime during your career• This is where the AAVSO enters the picture!
Small Telescopes and VSA
• VS Prototypes typically bright• Bright stars easier to observe via
spectroscopy, polarimetry, radio/Xray• Need to know solar neighborhood
before extrapolating to distant galaxies• Need extended observing time for light
curves• Need monitoring for transient events
Examples of projects
• Z UMi - an RCB star
• W Vir - the prototype cepheid
• Z Tau - a Mira
Z UMi - a circumpolar RCB
Real value of SRO is for long-term monitoring of many fields. Note near complete BVRI coverage (dropouts due to summer monsoon) of this circumpolar object. 15:02:01.3 +83:03:49
W Virginis coverage from SRO - one season
W Vir phased light curve, BVRI
Z Tau light curve, SRO
Z T a u
9
1 0
1 1
1 2
1 3
1 4
1 5
1 6
1 7
1 8
2 4 5 0 0 0 0 2 4 5 1 0 0 0 2 4 5 2 0 0 0 2 4 5 3 0 0 0 2 4 5 4 0 0 0 2 4 5 5 0 0 0
J D
Magnitude
A A V S O v i s u a l d a t a
S R O V d a t a
N O F S V d a t a
Z Tau field
USNO 1.55m
The AAVSO
• Dedicated to the study of variable stars• Founded 1911• 1200 members in 45 countries• 3000 total observers (800 active per year)• Both professional and advanced amateur• 15 million online observations• Campaigns, workshops, publications• http://www.aavso.org
History• Harvard photographic sky survey late 1800’s - early
1900’s• Enlisted local Boston amateurs to monitor newly
discovered variable stars• Strong association with Harvard College Observatory -
proam collaboration, AAVSO office at HCO until 1950’s• Moved off-campus 1954, remained in Cambridge• Computerized database in 1960’s• Microcomputers in 1980’s• Web in 1990’s• MySQL, VO, etc. in 2000’s
1918 Meeting
SS Cyg, 1896-2004
HQ - Cambridge, MA (about a mile from Harvard CollegeObservatory/CfA)
AAVSO Staff
Summary
• Big telescopes are not needed for cutting-edge science (try convincing review panels, though!)
• Small telescopes have the advantage that all components are commercially available, software provided
• Even small departments can afford such systems
• Best use is for studying variable stars
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