Scope
Overview
Data Release 15 is the third data release of the fourth phase of the Sloan Digital Sky Survey. It includes SDSS data taken through June 2017, and encompasses more than one-third of the entire celestial sphere. The coverage figures below show the sky coverage of DR15 for the eBOSS, APOGEE, and MaNGA surveys respectively (click figure to enlarge).
DR14/DR15 eBOSS spectroscopic coverage in Equatorial coordinates (plot centered at RA = 8h.)
DR14/DR15 APOGEE spectroscopic coverage in Galactic coordinates (plot centered at Galactic center). Fields that had new data in DR14 are circled.
DR15 MaNGA spectroscopic coverage in Equatorial coordinates. Grey shows potential fields (tiles), while blue shows the observed plates included in DR15.
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 15.
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)
(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
- u
- 1.3%
- g
- 0.8%
- r
- 0.8%
- i
- 0.7%
- z
- 0.8%
Optical spectroscopy data statistics
All programs combined
- Total spectra
- 4,851,200
- Useful spectra
- 4,151,126
- Galaxies
- 2,541,424
- Quasars
- 680,843
- Stars
- 928,859
- Sky
- 394,231
- Standards
- 88,788
- Unknown
- 217,055
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 | 3,008 | 2,913 |
| Spectra | 2,987,105 | 2,696,287 |
| All Galaxies | 1,608,987 | 1,493,503 |
| CMASS | 933,387 | 863,761 |
| LOWZ | 369,673 | 344,423 |
| All Quasars | 539,297 | 444,217 |
| Main | 242,556 | 212,156 |
| Main, 2.15 ≤ z ≤ 3.5 | 175,518 | 150,592 |
| Stars | 335,844 | 303,518 |
| Standard stars | 62,979 | 50,574 |
| Sky | 282,344 | 261,098 |
| Unclassified spectra | 229,418 | 201,549 |
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
DR15 comprises data for ~263,000 APOGEE targets, identical to that of DR14. These include ~231,000 science targets, located in distinct types of survey fields:
- ~13,000 stars
- in Bulge fields
- ~129,600 stars
- in Halo and Halo Stream fields
- ~76,000 stars
- in Disk fields
- ~3,200 stars
- in Satellite Galaxies fields
- ~400 stars
- in Kepler Objects of Interest (KOI) Program fields
- ~19,500 stars
- in Star Cluster fields
- ~13,300 objects
- in Ancillary Science fields
- ~1000 bright stars
- observed with the NMSU 1m telescope + APOGEE, including bright standards
Exact counts are given in the table below.
| Statistic | Total | Unique |
|---|---|---|
| Pointings | ... | 780 |
| Plates | 4,012 | 1,363 |
| All stars | 1,054,381 spectra | 263,444 stars |
| with NMSU 1-m | 1,438 | 1,018 |
| Commissioning data | 27,387 | 12,914 |
| Survey stars | 872,844 | 184,148 |
| with S/N > 100 | ... | 144,309 |
| with ≥ 3 visits | ... | 143,154 |
| with ≥ 12 visits | ... | 6,200 |
| Stellar parameter standards | 10,006 | 1,300 |
| Radial velocity standards | 288 | 15 |
| Telluric line standards | 128,974 | 23,611 |
| Ancillary science program objects | 37,369 | 12,641 |
| Kepler target stars | 34,789 | 17,218 |
