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Norbert Zacharias U.S. Naval Observatory Astrometry Department Cataloging Division nz@usno.navy.mil. From UCAC to URAT. acknowledgement. UCAC (CCD setup, survey): T.Rafferty, M. Germain, J.Pohlman, ... all observers & site support (O.Saa, D.Castillo ... T.Tilleman)
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Norbert Zacharias U.S. Naval Observatory Astrometry Department Cataloging Division nz@usno.navy.mil From UCAC to URAT
acknowledgement • UCAC (CCD setup, survey): • T.Rafferty, M. Germain, J.Pohlman, ... • all observers & site support (O.Saa, D.Castillo ... T.Tilleman) • M.Zacharias, C.Finch, G.Wycoff, .... • UCAC (proper motions): • S.Urban, W. van Altena, T.Girard, A.Klemola, D.Monet, ... • U-mouse (detector): • STA (R.Bredthauer, ...), G.Luppino ... • U-mouse (astrograph): • USNO instrument shop (G.Wieder, ...) • USNO management (R.Gaume, K.Johnston ...)
U S N OC C DA s t r o g r a p hC a t a l o g “red lens” astrograph + 4k CCD combined with early epoch photographic data
UCAC observing • 1997 – 2004 (all-sky completed) • 579 – 642 nm bandpass • R = 8 to 16 mag • positions accurate to 20 mas (10 – 14 mag) • incl. proper motions (various early catalogs) • thanks Bill ! SPM = major contributor • most accurate astrometry for fainter than Hip.
backend of astrograph x-y slide 4k camera
UCAC products • UCAC1 (2000) : part of Southern Hemisphere • UCAC2 (2003) : -90 to +50 deg decl. • UCAC3 (2009) : • all-sky coverage; re-processing all pixel data • much improved completeness (bright stars, doubles) • improved astrometry (empirical profile fits, global iterations) • improved proper motions bright: new data: AGK2 • improved proper motions faint: re-reduct. NPM, SPM • improved photometry (1 band)
re-processing pixel data • 4.5 TB compressed • dark, flat handling • double star fits • empirical profiles • identify overexposed • multi-level results, flags • keep “fit crash”
StarScan plate measuring • early epoch data for proper motions, bright stars • CCD camera, step-stare mode • accurate to <= 0.5 micrometer absolute • Zacharias et al. 2008, PASP • 1930 AGK2: 1,900 plates • 1976..1995 ZA: 2,300 plates • 1983..1990 BB: 900 plates
StarScan plate measure machine Washington, DC
KPNO 2.1 m extragalactic reference frame link
UCAC3 public release status • reductions completed: • pixel re-processing --> x,y data, various models • “plate adjustment”, systematic errors (model, FDP, CTE) • StarScan data up to RA, Dec; SPM: final model decisions • levelsof products, options for release: • mean position catalog (80 million stars, all sky) include only if >= 2 detections + PM available • extract and identify minor planets -> separate catalog • identify double stars -> flags in main catalog • individual epoch RA, Dec of all detections • pixel data images (very noisy, dark current ...)
US N ORo b o t i cAs t r o m e t r i cTe l e s c o p e 4-shooter camera plus new 0.85m telescope
URAT overview • USNO Robotic Astrometric Telescope • 0.85 m aperture, focal length = 3.6 m • 4.5 degree diameter field of view • large format detector (world largest CCD) • 2 px / FWHM at 1.0 arcsec seeing • 9 micrometer pixel size • 4 CCDs, each 95 mm on a side • 60 s / 240 s integration • 13 to 21 mag • goal 5 mas for 'well exposed stars'
URAT cut side view EOST, 2005
URAT FASA2 (EOST 2005)
status of URAT project • telescope: • optical design studies completed • primary mirror: delivered Feb. 2008 • no funding to complete new telescope • detector: • 10.5k by 10.5k CCD chip produced successfully • thinning of 2 science grade chips May/July 2007 • 10k camera complete, 1st light October 2007 • 4-shooter camera funded, delivery March 2009
URAT phase 1 = U-mouse • currently no funding for new telescope • take 4-shooter camera, put at astrograph • complete re-make of astrograph 2007/08 • move to CTIO or NOFS, begin new survey 2009 • 28 sq. deg. per exposure! • 11 mas per image coord. (well exposed star) • multiple sky overlaps per year, 7 - 18 mag • clocked anti-blooming: seems to work! • solve for positions, motions + parallax
STA1600B 4-shooter camera head concept – front view • Cryostat window – 350mm diameter, 300mm clear aperture.
sky area per hemisphere 25,000 sq.deg field size per exposure 25 sq.deg number of fields 1000 2 exposures / field / epoch 60, 240 sec time for 1 field (exp.pair) 6 min time for 1-fold sky overlap 100 hour avail. observ. time / year 2,200 hour (CTIO) ...dark time, good seeing 1,500 hour (CTIO) numb. sky overlaps in 2 years 30 at CTIO numb. sky overlaps in 2 years 15 at NOFS single measure precision 11 mas(cent.+atm) ...for well exposed stars R= 11..15; 40 mas R=17 end of operation random error 2 mas at CTIO end of operation random error 3 mas at NOFS systematic errors < 10 mas --> ??? U-mouse project numbers
summary • UCAC3: all-sky to 16th mag, catalog in 2009 • URAT -> Umouse: first light 2009 • 111 million pixel CCD detector on sky tested in 2007 • use re-furbished astrograph for phase 1, 2008 • get 4-shooter camera by March 2009 • observe 2-3 years per site (NOFS, CTIO) • catalog of positions, proper motions, parallaxes 2012 ?