twirl is a python-only astrometric plate solving package. It is suited for cases where the RA-DEC coordinates of the image center and the field of view is known, computing a WCS based on gaia reference stars.
twirl is based on the algorithm of Lang et al. 2009 (astrometry.net) and go through these steps:
- detection of stars in the image if not provided
- catalog query using image known center
- 4-points asterisms building and matching following Lang et al. 2009
- image recombination and wcs fit (astropy.wcs)
An offline version is under development (current version relies on a Gaia catalog query)
import twirl
stars = twirl.find_peaks(data)[0:15]
wcs = twirl.compute_wcs(stars, center, fov)
A more complete example is provided in docs/notebooks
pip install twirl