From UCAC to URAT

from UCAC to URATYale, 2008 Sep 20 1

From UCAC to URAT

Norbert Zacharias

U.S. Naval ObservatoryAstrometry Department

Cataloging Division

[email protected]


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.


modify dome at CTIO


observing at CTIO


backend of astrograph

4k camera

x-y slide


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


SPM astrograph in Argentina



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

levels of products, options for release:1) mean position catalog (80 million stars, all sky) include only if >=

2 detections + PM available

2) extract and identify minor planets -> separate catalog

3) identify double stars -> flags in main catalog

4) individual epoch RA, Dec of all detections

5) pixel data images (very noisy, dark current ...)


U S N OR o b o t i cA s t r o m e t r i cT e 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 optical design


URAT cut side view

EOST, 2005


URATFASA2(EOST 2005)


0.9 m primary mirror delivered, Feb.08


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


“U-mouse”

(if you can't get the “rat”,how about a “mouse”?)



10k camera dewar


astrographwith 10k camera


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 headconcept – front view

• Cryostat window –

350mm diameter,

300mm clear

aperture.


4-shooter camera dewar

assembly

G.Luppino


U-mouse project numbers

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=17end of operation random error 2 mas at CTIO end of operation random error 3 mas at NOFS

systematic errors < 10 mas --> ???


rebuilding astrograph in 24in dome


astrograph new tube assembly


USNO instrument shop Sep 2008astrograph tube assembly


fully funct. 10k chip

image16

outputs

STA2008

Sep 17


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

?

Documents

From UCAC to URAT