jwcf - JWST calibration field catalogs

Python interface to the HAWK-I and HST-based JWST calibration field catalogs. Both catalogs provide RA, Dec positions as well as estimated magnitudes for most JWST instruments + filters. Catalogs are bundled with the package as compressed FITS files (Astropy reads .fits.gz transparently).

Installation

pip install jwst-calibration-field

Or edtiable install:

git lfs install # This is required for the large catalog files to be downloaded along with the package
git clone https://github.com/spacetelescope/jwst-calibration-field
cd just-calibration-field
pip install -e .

Requires Python ≥ 3.8, numpy, astropy

Example usage

HAWK-I catalog:

from jwcf import hawki_catalog

catalog = hawki_catalog()
print(catalog.colnames)

HST catalog:

from jwcf import hst_catalog

# Default: 2017.38 epoch
catalog = hst_catalog()

# Any epoch (proper motions propagated from 2017.38 reference)
catalog = hst_catalog(decimal_year_of_observation=2026.0)

The result is an astropy.table.Table. Access columns via catalog['ra_deg'] (column) or catalog['radeg'].data (array).

Catalog details

• HAWK-I: LMC calibration field calibrated to Gaia DR2 reference
• HST: Dual-epoch (2006.39 + 2017.38) proper motions; positions propagated to any epoch. Gaia DR2 reference.

References

Anderson, J., Fall, M., and the Astrometry Working Group, The JWST Calibration Field: Absolute Astrometry and Proper Motions with GAIA and a Second HST Epoch, Technical Report JWST-STScI-007716, STScI

Sahlmann, J., 2019, Astrometric catalog for JWST focal plane geometric calibration, Technical Report JWST-STScI-006828 STScI

Sahlmann, J., 2017, Astrometric accuracy of the JWST calibration field astrometric catalog examined with the first Gaia data release, Technical Report JWST-STScI-005492, STScI

Contributing

Open issues or PRs for bugs, feedback, or features. New contributors welcome!

Licenses

BSD-3-Clause