JWSTSTARS

The JWST Resolved Stellar Population Early Release Science (ERS) Program obtained NIRCam and NIRISS imaging of 3 resolved stellar targets in the Local Group: globular cluster M92, ultra-faint dwarf galaxy Draco II, and star-forming dwarf galaxy WLM. NIRCam was the primary instrument and observed each target in 4 filters: M92 (F090W, F150W, F277W, F444W), Draco II (F090W, F150W, F360M, F480M), WLM (F090W, F150W, F250M, F430M). NIRISS was used in parallel and obtained imaging in 2 filters (F090W, F150W). The 3rd exposure of M92, for both NIRCam and NIRISS, is not included in the analysis as it suffered from excess astrometric jitter and cannot produce adequate photometry. See Weisz et al. 2024 for more details.

Data Releases

DR1: Release of photometric catalogs of M92, Draco II, and WLM (V1, Feb. 15 2024)

Using the imaging data described above, the ERS team developed JWST NIRCam and NIRISS modules for DOLPHOT, a crowded field stellar photometry package widely used in nearby galaxies. This data release includes the full, multiband photometric catalogs produced by DOLPHOT for each field and the id2 drizzled reference images used for astrometrically aligning images for each target. The NIRISS field for Draco II did not contain prominent member stars, and the photometric catalog is not included in this data release.  See the catalog description in the READMEfile.

The FITS images used for this data release have the following JWST pipeline versioning information: CAL_VER=1.11.4, CRDS_VER=11.17.2, and CRDS_CTX=jwst_p1147.pmap.

DR2: Release of epoch photometric catalog and the RR Lyrae catalogs of WLM (V1, Jul. 17 2026)

The team delivered catalogs of the light curves and pulsation parameters for the RR Lyrae (RRL) stars in WLM that were co-observed with JWST and HST. These catalogs were constructed using Tables 7 and 9 of Slaughter et al. (2026). These catalogs can be found under the WLM NIRCam observation on the Portal.

The epoch photometric catalog of the RRLs includes the Modified Julian Date (MJD), the image filter (where 0 corresponds to F090W and 1 corresponds to F150W), and the magnitude and its uncertainty measured by DOLPHOT at each epoch. The RRL star lightcurve parameter catalog includes the best-fit pulsation parameters, including the period, pulsation type, filter-specific amplitudes, filter-specific mean magnitudes, and their associated uncertainties for the WLM RR Lyrae stars co-observed with JWST and HST. It also provides the source IDs, right ascension (RA), declination (Dec), and the chi-square (χ²) metric of the fit.

For a detailed description of the catalogs, please refer to the README file.

Both the image observations and the catalogs are available in the MAST Portal and astroquery. Set the 'Provenance Name' filter to JWSTSTARS in the Portal Advanced Search to match all observations. Each catalog is organized as the member product of each reference image observation. They can be downloaded with their reference image as a bundle or individually retrieved by selecting in the download basket. The observations can also be retrieved programmatically using the astroquery.mast module. The code example below retrieves all products.

from astroquery.mast import Observations
all_obs = Observations.query_criteria(provenance_name="jwststars")
data_products = Observations.get_product_list(all_obs)
Observations.download_products(data_products)

• MAST Portal

  

  A web-based interface for cross-mission searches of data at MAST or the Virtual Observatory

  Portal

• MAST Astroquery

  

  Search for and retrieve JWSTSTARS data products programmatically.

  MAST Astroquery