stare operations experience and its data quality control
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STARE Operations Experience and its Data Quality Control
IAC
Roi Alonso
Hans Deeg
Juan A. Belmonte
HAO BoulderTim Brown
David Charbonneau
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #2
STARE telescope• Stellar Astrophysics and Research on Exoplanets.• HAO, NASA funding; IAC logistics and personnel.• Detection of first planet transit in 1999, during commision at
HAO• Located at Teide Observatory, Tenerife since July 2001• Schmidt optics, 10.1 cm Ø,
f=286mm. • CCD: 2k x 2k Loral, 15m pix• 6.1x6.1 deg2 FOV, 10.8 arcsec/pix • R, V, B manual filters.
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #3
Transit Detection Observations
STARE observation strategy:• One (two) field observed all night, typ. declination 30°-40°.• Observation of a field for 2 - 3 months ( 150-400 hrs)• R band exposures of 100 sec, 13 sec readout• typical field: few 1000 stars rms < 1%
Requirements :
•precision F/F better than 0.5%
•observational coverage O(103-4) hrs
•data points every few minutes
•surveying thousands of stars
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #4
In collaboration with similar projects
• PSST: Lowell Obsv., Arizona. T. Dunham, G. Mandushev
• SLEUTH: Mt. Palomar, California. D. Charbonneau, F. O’Donovan
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #5
Instrument control
• Hardware: 2 PCs: {Dome, Mount},{CCD,guiding}• Optical fiber interfaces computers telescope dome• Control software
– Unified user interface withVisual C++ (Windows98)
– Telescope: Orchestrate Scripting Software (Software Bisque):
– Dome: AutomaDome (Software Bisque):
– CCD: Pixel View (Pixel Vision)
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #6DLT, DVD
Operations schemeoperator opens dome, starts scriptAfternoon
Nightfall; if fieldhigh enough
End of night/fieldtoo low
Morning
script starts observations
PC butch (script) PC sundance
Mount+dome CCD+autoguide
script return telesc. to home pos
operator closes dome, saves data (2Gb/night)
Observingperiod
operator watchesweather;
closes if needed
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #7
Data reduction schemeraw data saved on DLT, now DVDTeide Obsv
IDL programs: quality control, image processing, photometry, classification, transit search
IAC, La Laguna
PSST Lowell, Sleuth Palomar
Confirmation of events in other’s data.
Combination of data from 3 sites and transit search in combined data
Future
HAO, BoulderCoordination of follow-up obsv.
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #8
STARE statusField
Observing
dateObserving
nights (Teide)Stars with
rms<1%
Observing time (h) (Teide)
Coll. Telesc.
Status
Jul-Oct 01 38 of 91 ~7300 195 1 Reduced
Boo1 Abr-Jul 02 39 of 118 ~1500 238 2 Reduced Teide and
Lowell
Cyg1 Jul-Oct 02 16 of 78 ~7300 67 2 Reduced Teide
Per2 Oct-Nov 02 30 of 58 ~6300 193 2 Reduced Teide
Cnc0 Feb-May 03 16 of 89 ? 127 2 Reduced Reduced Lowell
Her0 May-Jun 03 44 of 54 ~1600 291 3 Reduced All
Lyr0 Jul-Sep 03 ~50 of 68 ? 367 3 Red. Teide Lowell
Cyg0
42 And Sep03-Jan04 56 of 121 ~3000 397 3 Not reduced
27 Lyn Jan-Mar04 29 of 61 ? 103 3 Not reduced
Since March: Technical problems (110V supply, UPS)
Instrumental & atmospheric sources of false alarms
Sources : instrumental:•guiding errors (moving psf over zones with varying flat-field correct.)•temperature/focus variations
Sources : atmospheric:•unrecognized extinction variations (cirrus, dust)•simple high-sigma events in photon noise (star, sky), scintillation
“Transits are rare events in hugh data sets which compete with other rare events to become detected”
False alarm: any event that appears to be a transit, but isn’t
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #10
Astron. source of false alarms(Brown 2003)
Confusion from:• grazing eclisping binaries
• diluted eclising binaries (by foreground star)
• diluted eclising binaries (triple sys)
• Planetary transits
We look for:
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #12
Data quality control Photometric, moon rise
extinction sky bright.
guiding alignment
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #13
Data quality control Cirrus in early night
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #14
Data quality control Dusty night
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #15
Data quality control guiding unstable, moon setting
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #17
Follow-up tecniques for transit candidates
• Careful interpretation of the lightcurve:– non-transit-like shape, search for primary/secondary eclipses– verify that transit is compatible with planet (Seager & Mallén-Ornelas, 2003)
• Multicolor transit photometry (incidentially with higher spatial resolution)– detects many cases of Ecl. binaries.
• Imaging with very high resolution (adapt. optics)– indicates if there are nearby stars, potentially Ecl. Binaries
• Radial velocity measures– low res: may detect Ecl. binaries (false alarm rejection)
– high res: independent verification of planet
Reject astronomical sources of false alarms by a sequence of tests, from simple (light) to sophisticated (resource-intensive) ones:
STARE Operations Experience and its Data Quality Control
Potsdam, July04 #27
Summary and future• Routine transit search operation since 2001
• Operations will continue for at least 3 years
• Well-coordinated collaboration is in place for follow-up observations. Sequence of methods to reject false alarms.
• Some interesting planet candidates which need final verifications.
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