Ancillary Programs


The BHM project has a number of ancillary spectroscopic programs, which provide scientifically interesting targets when BOSS fibers are not assigned to core science projects. These have the goal of obtaining redshifts and classifications for candidate QSOs and bright galaxies selected via wide-area optical/IR surveys. These supplementary programs do not affect the overall SDSS-V MOS survey plan (allocation of exposure resources across the sky).

Gaia-unWISE AGN survey

Sky map of Gaia-unWISE QSO target density
Sky density of Gaia unWISE QSO targets selected as candidates for observation in dark time (v0.5.3 targeting)

This BHM-led program collects BOSS spectroscopy for a large sample of candidate QSOs. We downselect targets suitable for SDSS-V spectroscopy from the parent sample presented by Shu et al. (2019), who used applied a machine-learning approach to a combination of the Gaia DR2 and unWISE catalogues. The Gaia-unWISE AGN targets are distributed across almost the entire sky (except for the innermost Galactic plane and regions around the Magellanic Clouds), and so are well matched to the SDSS-V all-sky survey strategy. This is primarily a discovery program, and so we have excluded AGN targets having existing good quality optical spectroscopy in earlier SDSS iterations.

Bright Low-Redshift Galaxy Survey

This program seeks to measure redshifts and provide classifications for a sample of optically bright, low-redshift, morphologically resolved galaxies, selected from optical/IR catalogues. This program is primarily intended as a filler, with no expectation of a high degree of spectroscopic completeness.

Observational goals and requirements

The SDSS-V/BHM Ancillary projects seek to gather spectroscopic redshifts and classifications for large samples of candidate QSOs and galaxies.

These samples generally have only moderate surface density on the sky, and so benefit most from the widest area components of the SDSS-V survey.

Target selection and survey implementation

Further details of the algorithms and criteria used to select BHM ancillary target cartons are provided via the links below.

Targeting generation ‘v0.5.3’

The v0.5.3 generation of targeting was used during initial SDSS-V/FPS operations (2022-), below is a list of BHM Ancillary cartons it includes:

BHM-centric open fiber programs

A subset of the SDSS-V Open Fiber Program focus on BOSS (re-)observations of optical/IR/X-ray selected QSOs/AGN, and so have strong overlap with BHM’s core science themes. The carton names for these six open fiber programs are listed below.

  • openfibertargets_nov2020_11
  • openfibertargets_nov2020_18
  • openfibertargets_nov2020_26
  • openfibertargets_nov2020_27
  • openfibertargets_nov2020_30
  • openfibertargets_nov2020_33

Spectroscopic data released in DR18

No new data for BHM Ancillary targets is released in SDSS DR18

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