Overview
Astra is a software package that manages and orchestrates the analysis of Milky Way Mapper spectra. Astra ingests the reduced data products from the APOGEE and BOSS data reduction pipelines and produces science-ready data products that store stellar parameters, chemical abundances, line measurements, and other quantities.
The motivation for Astra arises from the expanded quantity and scope of stars that are targeted in SDSS-V compared to earlier versions of SDSS. In SDSS-III and -IV, APOGEE-1 and -2 used the APOGEE instruments to collect stellar spectra, with an emphasis on red giant branch stars. In SDSS-V the Milky Way Mapper includes both APOGEE and BOSS spectra of all stellar types and evolutionary states: from M-dwarfs to white dwarfs. Between these extremes there is different physics that dominates in their photospheres, implying that an analysis pipeline which is suitable for M-dwarfs is probably unsuitable for white dwarfs.
Although this is an extreme example, it is common in Milky Way Mapper. This motivates us to pursue multiple analysis pipelines that we can execute over sets of data, and generate data products that are self-documented and science-ready. This is the purpose of Astra; it is the glue that brings together analysis methods into a single software framework.