MWM Science Validation

The relative sizes of Jupiter, Proxima Centauri, the Sun, and Sirius
Image Credit: JoeyPknowsalotaboutthat, CC BY-SA 4.0, via Wikimedia Commons

The Milky Way Mapper needs fundamental parameters for stars, white dwarfs, and binary systems to complete its science goals. We also desire to understand how results obtained from high-resolution near-IR APOGEE spectra compare to results obtained from low-resolution optical BOSS spectra. More globally, we plan to compare our results with other large-scale spectroscopic surveys of the Milky Way, including DESI, WEAVE, and 4MOST. Therefore, there are several curated cartons implemented or planned for MWM.

In DR19, only one of these dedicated cartons has been implemented. However, the extensive data taken on the APOGEE and BOSS instruments that will be reduced with the MWM pipelines for other science programs (including cluster stars and stars with asteroseismic parameters) will also be used for validation.

Cartons

manual_validation

The stars in both the manual_validation_apogee and manual_validation_boss cartons were chosen from the 4MOST, DESI, PSF and WEAVE surveys with the goal of comparing between surveys and establishing a strategy that will put all stellar parameters onto the same scale. There are also stars from Open Cluster, Globular Clusters, low reddening stars, Gaia Benchmark stars, planet hosts, and, for BOSS, APOKASC stars all for calibration purposes.

mwm_legacy_ir2opt

This carton’s goal is to obtain BOSS spectra for stars observed by APOGEE to aid in the calibration of BOSS data. The high-quality information from the APOGEE spectra can be used for empirical derivations of stellar parameters from BOSS spectra. This carton uses Gaia DR2 magnitudes to ensure that the stars are not too bright in the optical.

The target selection relies on the Legacy APOGEE “Merge File” table (mos_sdss_apogeeallstarmerge_r13), described in detail under the mwm_rv_long_bplates carton in the Binary program. This table consolidates duplicate entries of the APOGEE allVisit and allStar files from DR16 and is available on the SAS and on CasJobs. The full selection criteria are:

  • Target is in APOGEE DR16 “Merge File”
  • 13 < G < 18
  • GBP > 13
  • GRP > 13

Cadences

During plate observations, these targets could be observed on any plate with an MWM-led cadence.

During FPS observations, all mwm_legacy_ir2opt targets use the bright_1x1 cadence on the BOSS instrument.

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