The Scope of DR9

A paper accompanies the data release which details the differences between DR9 and its predecessors. Major differences from the DR8 release are:

1. Updates to the astrometric positions and proper motions in the imaging.
2. New stellar parameters for SDSS spectrograph data
3. 831,000 new spectra from the BOSS spectrograph data

To check whether a location is covered in DR9 please use the form below. Enter RA/Dec coordinates in the box, in decimal degrees, and click Submit. Your coordinates will be loaded into the DR9 Science Archive Server (SAS). If your point is in the DR9 survey area, results will include links to all available SDSS imaging and spectroscopic data.

RA/Dec Coverage Check:

180.00 50.00

DR9 imaging and spectroscopic coverage in Equatorial coordinates (plot centered at RA = 6h, or 90 deg.)

The data is defined as a set of photometric runs and a set of spectroscopic plates (see the basics on imaging and spectroscopy). We provide links here to ASCII and FITS lists of the runs and the plates. These lists are essentially a summary of all of the data in the data release.

• List of runs: photoRunAll-dr9.par, photoRunAll-dr9.fits
• List of plates: plates-dr9.par, plates-dr9.fits

SDSS-III has committed to publicly release its raw and reduced data sets. We are doing so using the Catalog Archive Server for retrieval of catalog data from a powerful SQL database and a Science Archive Server for retrieval of calibrated spectra and images.

Imaging data statistics

Total unique area covered	14,555 square degrees
Total area of imaging (including overlaps)	31,637 square degrees (excluding supernovae runs)
Individual image field size	1361x2048 pixels (0.0337 square degrees)
Number of individual fields	938,046 (excluding supernovae runs)
Number of catalog objects	1,231,051,050
Number of unique detections	932,891,133
Number of unique, primary sources	Total 469,053,874 Stars 260,562,744 Galaxies 208,478,448 Unknown 12,682
Effective wavelengths and magnitude limits (95% completeness for point sources)	u g r i z 3551 Å 4686 Å 6165 Å 7481 Å 8931 Å 22.0 22.2 22.2 21.3 20.5
Median PSF FWHM, r-band	1.3 arcsec
Pixel scale	0.396 arcsec
Exposure time per band	53.9 sec
Time difference between observations of each band	71.72 sec (in riuzg order)
Relative photometric calibration accuracy (RMS) (Padmanabhan et al. 2008)	u g r i z 1.3% 0.8% 0.8% 0.7% 0.8%
Global astrometric precision	0.1 arcsec rms (absolute)

Spectroscopic data statistics

	SDSS spectrograph	BOSS spectrograph
Area covered	Full unique coverage 9274 square degrees SEGUE-1 coverage 1438 square degrees SEGUE-2 coverage 1317 square degrees Legacy coverage 7966 square degrees	Full unique coverage 3,275 square degrees
Number of plates	Category Total Good/ marginal Primary All programs 2880 2764 2654 Legacy 1926 1869 1794 SEGUE-1 442 427 407 SEGUE-2 211 211 204 Special 301 257 246	Category Total Good/ marginal Primary All programs 831 831 819 BOSS 809 809 801 Special 22 22 18
Plate area	1.49 deg radius, 6.97 deg2	1.49 deg radius, 6.97 deg2
Fibers per plate	640	1000
Numbers of spectra	Category Total On good or marginal plates Unique All programs 1,843,200 1,768,960 1,629,129 Main galaxy targets 778,410 755,111 711,726 LRG targets (excluding Main) 106,650 103,662 95,990 SEGUE-1 targets 250,422 242,008 220,851 SEGUE-2 targets 128,112 128,112 118,151 Stars 600,967 577,157 521,990 Galaxies 952,740 921,007 860,836 QSOs 130,300 126,368 116,003 Skies 110,288 103,046 93,187 Unknown 48,905 41,382 37,113	Category Total Unique Total 831,000 763,425 Stars 90,897 82,645 Galaxies 535,995 493,845 QSOs 102,100 93,003 Sky 78,573 75,850 Unknown 62,303 54,978
Wavelength coverage	3800 to 9200 Å	3600 to 10,400 Å
Resolution	1800 to 2000	1400 to 2600 Å
Median S/N	at g(fiber) = 20.2 mag, 4.2 per pixel (Legacy) 7.0 per pixel (SEGUE-1, -2)	at i(fiber) = 21 mag, 6.1 per pixel
Typical redshift accuracy	30 km/s rms for main galaxy sample (from repeat observations) 4.0 km/s rms for SEGUE near g=18th mag (from repeat observations) 1.8 km/s systematic limit for high signal-to-noise stars	65 km/s rms for LRG sample (from repeat observations) 1.8 km/s systematic limit for high signal-to-noise stars
Approximate magnitude limits (Corrected for Galactic dust extinction)	Main sample galaxies Petrosian r < 17.77 Strauss et al. (2002) Luminous Red Galaxies Petrosian r < 19.2 Eisenstein et al. (2001) z < 3 quasars PSF i < 19.1 Richards et al. (2002) z > 3 quasars PSF i < 20.2 Richards et al. (2002) SEGUE-1 Faint PSF 17.8 < r < 20.1 Yanny et al. (2009) SEGUE-1 Bright PSF r < 17.8 Yanny et al. (2009) SEGUE-2 PSF r < 20.2	LRGs i < 19.9 White et al. (2011) QSOs g < 22 i < 22 Ross et al. (2012)

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