BHM Data

New data for BHM in DR20

BOSS spectra

SDSS DR20 includes the release of a total of ~1.1M spectra for ~490,000 distinct objects primarily targeted for spectroscopy by BHM (a 3-4x expansion vs. DR19). These extend across nearly the full suite of main BHM science programs. DR20 includes not only northern and equatorial fields (from APO), but also a marked expansion to southern fields (from LCO), and with BOSS optical spectra taken for AQMES, RM, SPIDERS, CSC, and BHM-related ancillary science programs from APO and LCO (up to early February of 2025) . Additional more-detailed information on spectra, spectroscopic parameters, and targeting aspects in DR20 may also be found in links from the right hand menu.

Distribution on the sky in RA and Dec for ~0.49M distinct objects encompassed by this DR20 release, targeted primarily for optical BOSS spectroscopy by BHM. Black Hole Mapper often takes multiple BOSS spectra of the same object/target, to achieve adequate S/N for the intended science, and/or for spectroscopic time-domain studies. A total of ~1.1M spectra of the ~0.49M distinct BHM objects are included, and the color coding (logarithmically) depicts the number (per object) of such DR20 spectra for each of the ~0.49M BHM targets.
Distribution of apparent magnitudes and redshifts (as provided by the spectroscopic pipeline) for the same ~0.49M BHM objects,with DR20 BOSS optical spectroscopy. The color coding again depicts the number of spectra (per object) released here in DR20 for each of these BHM spectroscopic targets (e.g., sometimes indicative of time-domain spectroscopic monitoring of the target). DR20 represents a marked (3-4x) expansion in BHM spectroscopic coverage, including extending now into the Southern sky (e.g., where many of the SPIDERS targets are accessible). These spectra span nearly the full set of BHM science programs.
Sky density of BHM targets having at least one BOSS spectrum in DR20. Here we include all targets that are a member of any BHM core or filler carton. We also include here any BHM targets that were primarily targeted because they overlap with other programs (i.e. led by MWM). However, we do not consider extragalactic openfiber cartons in this case.

Value Added Catalogues

As with previous SDSS data releases, DR20 also includes a number of Value Added Catalogs (VACs). These VACs, including several associated with BHM projects, provide more detailed and/or more scientifically focused views of the spectroscopic data.

Previous SDSS data most relevant to BHM

Please also see earlier SDSS data releases, including DR16, DR17, DR18 , and DR19 which e.g., include BHM relevant science and data, from other earlier SDSS programs and releases.

DR17 and earlier (SDSS-I,II,III and IV)

DR18 and DR19 (SDSS-V)

Please note that DR20 is a cumulative release, it includes all SDSS-V data that were previously included in DR18 and DR19. Therefore, in most cases, we suggest that users refer to the DR20 data set.

  • SDSS-V eFEDS plate data in DR18 which extended BOSS (joint with APOGEE) spectra to 37 plates, for (mostly) X-ray selected targets in the eROSITA eFEDS field.
This image has an empty alt attribute; its file name is eFEDS_SDSS_map_plates_DR16_Mar2020_SDSSV_spectra-2-1024x512.png
BHM/SPIDERS eFEDS-followup in data releases through DR18: The SRG/eROSITA mission completed a mini-X-ray survey of a 140 sq. deg. region (called eFEDS; Brunner et al. 2022) in 2019. Starting in SDSS-IV & completed during SDSS-V, BOSS spectra were extended to encompass ~12,000 counterparts of eFEDS X-ray sources, including quasars/AGN (which dominate), clusters of galaxies, & Galactic X-ray sources. Such SDSS-V eFEDS spectra were a major component of SDSS DR18; for additional details, see Almeida et al. (2023); Aydar et al. (2025).
  • SDSS-V DR19 included the release of a total of ~380,000 BOSS spectra for ~120,000 distinct objects primarily targeted for spectroscopy by BHM, an order of magnitude expansion vs. DR18. These extended across nearly the full suite of main BHM science programs, but emphasizing especially northern and equatorial fields, and with BOSS optical spectra taken for AQMES, RM, SPIDERS, CSC and BHM-related ancillary science programs from APO (up to July 2023) .
Distribution on the sky in RA and Dec for ~120k distinct objects encompassed by the previous DR19 release, targeted primarily for optical BOSS spectroscopy by BHM. A total of ~380k spectra of the ~120k distinct BHM objects were included, and the color coding (logarithmically) depicts the number (per object) of such DR19 spectra for each of the ~120k BHM in DR19 targets.
Distribution of apparent magnitudes and redshifts (as provided by the spectroscopic pipeline) for the ~120k BHM objectswith DR19 BOSS optical spectroscopy. The color coding again depicts the number of spectra (per object) released in DR19 for each of the BHM DR19 spectroscopic targets. DR19 represented an order of magnitude expansion in BHM spectroscopic targets encompassed, and in the numbers of spectra released vs. DR18.

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