spacetelescope / gaia_alignment

Gaia Alignment

This repository contains tools used for aligning HST images to Gaia. This workflow is especially good for large mosaics/datasets multiple points but little to no overlap. Currently, an example workflow is contained in a Jupyter notebook, though more notebooks/scripts may be added later in order to provide a more complete drizzling workflow.

The code currently provides functionality to determine the query region, perform the query, and pass the resulting catalog into TweakReg. Examples querying other services (such as MAST and DSS images) are also included. The notebook uses a small subset of data from a larger HST program as an example, but the process is very scalable. The full program was mosaicked using the same process:

Requirements

To run this notebook successfully, you will need an astroconda environment running Python (2.7 hsould work, but the code was written in 3.5).

You will also need to install the astroquery package:

$ conda install -c astropy astroquery

gaia_alignment's Issues

Add other catalogs

As @mgennaro suggested, it could be could to supplement Gaia's source lists with catalogs from other surverys, like PanSTARRS/VISTA.

Would probably need to first get the secondary catalog, align that to Gaia via spacetelescope/drizzlepac#77 and then use that aligned catalog with TweakReg.

Make visit level drizzling notebook

My typical workflow initially drizzles data taken in the same visit and filter. This creates higher SNR images used for source detection, and filters CRs. Creating a notebook or script to do this, as well as applying the the tweaked WCS to the headers of the input FLTs will likely create a more efficient processing for users.

Reference files are needed

For users who don't have the iref/jref environmental variables and reference files locally, the reference files should be downloaded. The following cell does the job if you add it after the MAST downloads:

from urllib.request import urlretrieve 

os.environ['iref'] = '~/iref/'
if not os.path.exists('iref'):
    os.mkdir('iref')

os.environ['jref'] = '~/jref/'
if not os.path.exists('jref'):
    os.mkdir('jref')

base_url = 'https://hst-crds.stsci.edu/unchecked_get/references/hst/'

files = glob.glob('data_download/mastDownload/HST/*/*fl?.fits')

for file in files:
    with fits.open(file) as hdu:
        for key in ['IDCTAB','NPOLFILE','D2IMFILE']:
            reffile_name = hdu[0].header[key].replace('$', '/')
            print(reffile_name)
            if not os.path.exists(reffile_name):
                urlretrieve(base_url + os.path.basename(reffile_name), reffile_name)

Update the help

Tyler Desjardins mentions that we should consider moving emails from help[at]stsci.edu to point to the web portal where possible and appropriate. For HST (or any non-JWST), it is https://hsthelp.stsci.edu . For JWST, it is https://jwsthelp.stsci.edu . Please update info in setup.py, setup.cfg, documentation, etc as appropriate.

Please close this issue if it is irrelevant to your repository. This is an automated issue. If this is opened in error, please let pllim know!

xref spacetelescope/hstcal#317