Scope

Overview

Data Release 16 is the fourth data release of the fourth phase of the Sloan Digital Sky Survey. It includes SDSS data taken through August 2018, and encompasses more than one-third of the entire celestial sphere. The coverage figures below show the sky coverage of DR16 for the eBOSS, APOGEE, and MaNGA surveys respectively (click figure to enlarge).

DR16 eBOSS spectroscopic coverage in Equatorial coordinates (plot centered at RA = 8h.)
DR16 eBOSS spectroscopic coverage in Equatorial coordinates (plot centered at RA = 8h.)
Distribution of APOGEE fields. Each field is color-coded by the number of targets in that field in DR16. Image credit: C. Hayes
Distribution of DR16 APOGEE fields. Each field is color-coded by the number of targets in that field in DR16. Image credit: C. Hayes
DR15/DR16 MaNGA spectroscopic coverage in Equatorial coordinates. Grey shows potential fields (tiles), while blue shows the observed plates included in DR15/DR16.
DR15/DR16 MaNGA spectroscopic coverage in Equatorial coordinates. Grey shows potential fields (tiles), while blue shows the observed plates included in DR15/DR16.

With so much sky being mapped in so many different ways, questions about the size of the SDSS can be answered in many different ways. This page details the SDSS survey area and provides various ways to count the data of Data Release 16.

Imaging statistics

Total unique area covered
14,555 square degrees
Total area of imaging (including overlaps)
31,637 square degrees (excluding supernova runs)
Individual image field size
1361x2048 pixels (0.0337 square degrees)
Number of individual fields
938,046 (excluding supernova runs)
Number of catalog objects
1,231,051,050
Number of unique detections
932,891,133
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)
Global astrometric precision
0.1 arcsec rms (absolute)
Number of unique, primary sources
Total
469,053,874
Stars
260,562,744
Galaxies
208,478,448
Unknown
12,682
Effective wavelengths & magnitude limits
(95% completeness for point sources)
u
3551Å
22.0
g
4686Å
22.2
r
6165Å
22.2
i
7481Å
21.3
z
8931Å
20.5
Relative photometric
calibration accuracy (RMS)

(Padmanabhan et al. 2008)
u
1.3%
g
0.8%
r
0.8%
i
0.7%
z
0.8%

Optical spectroscopy data statistics

All programs combined

Total spectra
5,789,200
Useful spectra
4,846,156
Galaxies
2,863,635
Quasars
960,678
Stars
1,021,843
Sky
475,531
Standards
108,603
Unknown
352,320

Stellar (SEGUE)

Effective area (deg2)
1,317
Plates
229
Total spectra
155,520
Unique objects
138,099

Exoplanets (MARVELS)

Targets
11,040

Extragalactic (BOSS/eBOSS)

Statistic Total Unique
Spectroscopic effective area (deg2) ... 9,376
Plates 3,946 3,803
Spectra 3,946,000 3,518,265
All Galaxies 1,913,705 1,775,300
    CMASS 980,922 904,686
    LOWZ 374,913 349,071
    eBOSS LRG 298,762 279,304
    eBOSS ELG 269,889 252,308
All Quasars 1,032,126 919,221
    BOSS 447,204 386,728
    eBOSS 584,922 532,493
Stars 428,828 385,800
    Standard stars 83,345 65,247
Sky 365,243 330,731
Unclassified spectra 410,338 361,383

IFU spectroscopy (MaNGA)

Total galaxies
4688
Unique galaxies
4621
Plate scale
7 deg2
IFUs per plate
17
Wavelength
3600-10,000 Å

MaNGA Stellar Library (MaStar)

Total high-quality spectra
8646
Unique stars
3321
Plate scale
7 deg2
IFUs per plate
17
Wavelength
3600-10,000 Å

Infrared (APOGEE) spectroscopic data statistics

DR16 contains data for approximately 430,000 unique APOGEE targets in 1442 fields, of which roughly 300,000 are main survey targets. A total of 1,800,000 individual visits are included in DR16. A general breakdown of targets in DR16-associated programs follows below:

~34,000 stars
in Bulge fields
~57,600 stars
in Halo and Halo Stream fields
~89,000 stars
co-observed on MaNGA plates
~128,000 stars
in Disk fields
~11,200 stars
in Satellite Galaxies fields
~28,000 stars
in Young Cluster fields
~72,000 stars
for Photometric Objects of Interest (POIs) in the Kepler, K2, CoRoT, and TESS footprints
~13,300 objects
in Ancillary Science fields
~35,000 objects
in External Program fields
~1000 bright stars
observed with the NMSU 1m telescope + APOGEE, including bright standards