aperture_phot.py — Forced PSF-weighted photometry on difference images

aperture_phot.py v1.6 — Professional forced PSF photometry for time-domain surveys  
(TESS, ZTF, LSST/Rubin, ASAS-SN, etc.).

Given a deep reference image + any number of science or difference images and a target list (RA/Dec or x/y),  
the script automatically:

• Builds an empirical Gaussian PSF from bright stars in the reference  
• Performs optimal forced photometry at fixed positions across every epoch  
• Uses local background noise estimates for correct uncertainties  
• Gracefully handles missing/bad WCS, NaNs, and unaligned images  
• Outputs a clean, publication-ready CSV light-curve table  
  (MJD, instrumental flux [ct], flux_err, mag, mag_err, flag)

Zero interactive steps · thousands of epochs in minutes · no external dependencies beyond astropy/photutils.

Made by Britt (2025) — MIT License