An project

A Roadmap to Photometric Redshifts for the LSST Object Catalog

  • M. L. Graham
  • J. Bosch
  • L. P. Guy

  • the DM System Science Team.


This roadmap guides the Rubin Observatory Data Management (DM) team’s efforts to engage with the scientific community of data-rights holders in order to implement and validate one or more existing photometric redshift (photo-z) estimators into the Data Release (DR) processing pipeline, and serve the resulting photo-z data products for the DR Object catalogs.

The DR Object catalog photo-z estimates will initially meet a set of minimum scientific attributes and serve the widest variety of science applications. DM will select one or more existing, community-vetted algorithms to generate the DR photo-z. The evaluation criteria will include technical considerations related to the DM System.

The Rubin science community has a considerable wealth of expertise in generating photo-z catalogs and will be the primary users of the DR Object catalog photo-z data products. Therefore, the evaluation, implementation, and validation of the DR Objects photo-z estimator(s) will be a joint venture between the Rubin construction team and the Rubin science community.

This roadmap is a living document to guide this joint venture, and it will evolve over time to incorporate input from the science community. In 2021, community input regarding the evaluation criteria for photo-z estimators, and which kind of photo-z estimator(s) should be selected, was gathered via DM’s series of “LSST Photo-z Virtual Forums" and photo-z “Letters of Recommendation" (LOR). This input has been incorporated into § [sec:eval] and [sec:lor].

Further on in this roadmap DM will facilitate science community participation in a “Photo-z Validation Cooperative" based on commissioning data for the shortlisted estimators (§ [sec:pzcoop]; dates TBD).

This roadmap includes possible in-kind contributions from international partnerships to Object catalog photo-z for DR1 and beyond, as well as potential processes of improving the DR Object catalog photo-z and/or federating user-generated photo-z catalogs during Rubin operations.