Welcome to the WFC3 Photometric tools repository. In this repository there are two sets of tools. The photometry_tools directory contains typical utility functions for doing aperture photometry and also creating radial profiles of sources. The psf_tools directory contains a module that provides an interface for performing PSF photometry on WFC3 images using the effective PSF models developed by Jay Anderson- described in Anderson & King (2000, PASP) and WFC3 ISR 2016-12. This fitting derives fluxes and positions typically down to the 0.01 mag and 0.01 pixel level, which is currently not achievable with other software. The user has the choice of which of the two fitting engines to work with- a Fortran program written by J Anderson which is called via a python wrapper, or a fully Python engine. The fortran engine has more features, and is much faster, though documentation is sparse compared to the python engine. The outputs from either are virtually equivalent.
After the PSFs are fit, there are then tools available to align the images using the psf catalogs, and collate/average the catalogs into a final, fully calibrated catalog. A Jupyter Notebook is available in this top level directory for full instruction on the usage of psf_tools, and is recommended reading for those interested in using the tools.
This software is still in beta, and will have slight improvements/optimizations done in the comming months, but should not have any changes with regards to inputs and outputs. At the very least, the module will be upgraded into a full package, with a steup.py, and placed onto PyPI for easier installation. However, the tools are fully functional as of now, and the outputs are extremely high fidelity catalogs.