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Calibration of the Bright Sky with APASS

The AAVSO Photometric All-Sky Survey (APASS) provides quasi-simultaneous B, V, g', r', i' photometry for stars in a 3-degree field of view. With a final accuracy of 0.02mag, this survey covers 85% of the sky. The data is used by various projects including RAVE, DASCH, and UCAC4. Find more information at http://www.aavso.org/apass

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Calibration of the Bright Sky with APASS

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  1. Calibration of the Bright Sky with APASS Arne Henden Director, AAVSO arne@aavso.org

  2. AAVSO Photometric All-Sky Survey (APASS) • B,V,g’,r’,i’ quasi-simultaneous • 3-degree field of view, 2.6arcsec pix • 10<V<17, 0.02mag final accuracy • Funded by R. M. Ayers Sciences Fund • Located in NM and Chile • 85% sky currently covered twice in DR5; 40 million stars. Final product in 2 years • Used by RAVE, DASCH, UCAC4

  3. APASS sites http://www.aavso.org/apass South (CTIO) North (NM) ASA N8 20cm astrographs Paramount ME Apogee U16m cameras Apogee filter wheels Astrodon filters MaximDL/ACP/Scheduler Linux/Windows VM

  4. AAVSO Finding Charts

  5. Synoptic Survey 2 simultaneous passbands Entire sky, once/night 10<V<17 On-sky calibration from APASS Fully public data First 8K square degree site Jun 2012 M51 first light RH300 on Paramount MX, Sudbury MA

  6. Timeliine • Oct 2009 First light (north) • Sep 2010 First APASS data release • Nov 2010 First light (south) • Feb 2011 Second light (north) • Jan 2012 Current data release (DR5) • May 2012 DR6 (last primary survey) • Jan 2013 DR7 (most of secondary survey) • 2014 Final catalog

  7. Operations/Pipeline Queue-scheduled via ACP Scheduler 80 fields per night (20 standards) 20GB raw images/night Iraf/daophot processing, local linux Images stored on external HD, transferred via FedEx bimonthly Starlists transfered via ftp to AAVSO HQ WCS (2step), transformation done at HQ MySQL DB created after culling

  8. Flatfield

  9. Illumination Correction OTA1 OTA2

  10. Current results Photometry good to 0.03mag accuracy Differential photometry in single field 0.01mag Saturation 10mag, faint limit (S/N=5) 16.5mag Astrometry 150-200mas Bright time used for cepheid, Kepler, ToO targets Starting bright survey (saturation 7.5mag) during bright time Starting z’,Y extension this summer

  11. APASS DR5 Coverage

  12. Community Access • Direct MySQL query: http://www.aavso.org/download-apass-data • Interactive graphical display: http://www.aavso.org/seqplot • Download full catalog: • http://184.73.185.143/APASS/apass_dr5a.zip • http://184.73.185.143/APASS/apass_dr5b.zip

  13. Downtime • Full moon (5 nights per lunation) 15% • Weather (especially north) 35% • Hardware/software 20% • Human (not avail; ACP) 5% • Total loss: 75% • Current efficiency: 60%

  14. Hardware/Software Problems • Wrong B filter • Hyperbolic primary on one OTA • Power failures (web power switch) • Filter wheel failure • Camera sensor failure • Paramount PEC, hard limits • Apogee USB non-ID • Computers (especially north) • OTA delivery delays • Camera/filter wheel delivery delays • ACP January bug • Scripting errors

  15. North OTA problem OTA1 OTA2 ASA delivered wrong primary mirror. 3-month delay to get new mirror

  16. Hardware/Software Problems • Wrong B filter • Hyperbolic primary on one OTA • Power failures (web power switch) • Filter wheel failure • Camera sensor failure • Paramount PEC, hard limits • Apogee USB non-ID • Computers (especially north) • OTA delivery delays • Camera/filter wheel delivery delays • ACP January bug • Scripting errors

  17. South LED camera defect Grew over several nights Required replacement of sensor (under warranty) Kodak took 4 months to deliver sensor to Apogee

  18. DR5 Problems B filter has red leak (new filter will be installed in June; previous results can be back-corrected). Only affects stars (B-Ic)>5 Some poor photometry from non-photometric nights (but errors reflect this) Corners retained Saturated stars retained Blended objects left blended (photometry, astrometry) Stars with photometric errors == 0.000

  19. Vapass vs. Vlandolt

  20. (B-V)apass vs. (B-V)landolt

  21. SPM4 Comparison

  22. Future Sextractor (or similar) for better centroiding Psf-fitting for crowded fields Astrometry.net matching for lost nights/images Plate distortion maps for improved astrometry (100mas) Stacking to get ~1mag fainter Weighted photometric means Final global reduction for homogeneity

  23. Stephen Levine (Lowell) Dirk Terrell (SwRI) Doug Welch (McMaster) Dan Reichart (UNC) Kevin Ivarsen (UNC) Tom Smith (DRO) Matt Templeton (AAVSO) Mike Simonsen (AAVSO) Sara Beck (AAVSO) Doc Kinne (AAVSO) Ben Davies Gary Myers Bill Goff Alson Wong John Gross Ed Los Tim Puckett (Apogee) Walter Hildebrand (ASA) Tom Bisque (Software Bisque) Don Goldman (Astrodon) Bob Denny (DC3) Many Thanks...

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