The Sloan Digital Sky Survey started operations with its first light in 1998, and has been collecting data ever since, first with an imaging camera, and later with spectrographs. Below we list the total number of stars, galaxies, and quasars for which SDSS spectra are available, as well as the total number of spectra that are provided by the SDSS data systems.
So far, SDSS has taken spectra of over 4M stars, 3M galaxies, and 2M quasars. For optical targets, these counts are based on the classifications done in the boss data reduction pipeline. We have not excluded any targets with low-quality or other data quality warning flags. Unique targets are identified by sdss_primary and boss_primary in specObj files for SDSS-I-IV, and by sdss_id in the allspec file for SDSS-V.
| stars (optical) | stars (infrared) | galaxies (optical) | galaxies (IFU*) | quasars | LVM tiles(**) | TOTAL | |
| SDSS-I/II | 582,123 | – | 908,423 | – | 162,565 | – | 1,653,111 |
| SDSS-III/IV | 482,466 | 635,964 | 2,063,697 | 10,160 | 978,054 | – | 4,160,181 |
| SDSS-V | 2,056,399 | 390,676 | 399,221 | – | 946,932 | 169 | 3,793,228 |
(*) The galaxies observed with integral-field spectroscopy in the MaNGA survey were previously observed with optical spectrographs in SDSS-I-III, and therefore not included in the total number of targets observed. The number of IFU galaxies is based on the MaNGA ‘identifying unique galaxies tutorial‘, and does not take into account cubes from non-galaxies programs.
(**) We are releasing 169 Local Volume Mapper (LVM) tiles in DR20, to provide a preview of the SDSS-V IFU data, with much more to follow in future data releases. As the LVM tiles are mapping extended parts of the Milky Way and extra-galactic targets, we are not counting them towards the total number of targets observed.
To give you a sense of the full dataset, below we are listing the total number of spectra (or cubes/tiles) we make available in SDSS, taken from the DR20 allspec file (v1.0.2). This includes calibration and commissioning spectra, and the spectra are not filtered on quality. This includes both individual visits as well as combined and various co-added spectra. Be aware that therefore there is some double-counting here: a spectrum from a single visit will be counted both as an individual spectrum, and in any combined or co-added spectrum it was included into.
| optical spectra | infrared spectra | IFU cubes/tiles | TOTAL (*) | |
| SDSS-I/II | 1,843,200 | – | – | 1,843,200 |
| SDSS-III/IV | 3,958,000 | 3,390,236 | 11,273 | 7,359,509 |
| SDSS-V | 17,245,526 | 1,223,269 | 169 | 18,468,795 |
| TOTAL | 23,046,726 | 4,613,505 | 11,442 | 27,671,504 |
(*) This column includes both optical and infrared spectra, as well as IFU cubes. Note that SDSS-V LVM tiles are not included in the allspec file (yet).
Optical spectra include spectra taken by the SDSS and BOSS spectrographs for the legacy, SEGUE, BOSS, eBOSS, BHM and MWM surveys, while infrared spectra are taken by the APOGEE spectrographs for the APOGEE-1, APOGEE-2 and MWM surveys. IFU cubes and tiles are contributed by the MaNGA and LVM surveys, respectively.
For now, MARVELS and MaStar are not included in the allspec file and in the two tables above: their statistics can be found here.