Photutils - Astronomical Photometry

Photutils is the modern standard for extracting quantitative data from astronomical images. It replaces legacy tools like SExtractor or DAOPHOT with a modular, Pythonic interface integrated with the Astropy ecosystem.

When to Use

• Detecting stars or galaxies in an astronomical image (DAOStarFinder, IRAFStarFinder).
• Measuring the brightness of objects using circular, elliptical, or rectangular apertures.
• Performing PSF-fitting photometry (essential for crowded stellar fields).
• Estimating and subtracting complex 2D backgrounds (sky background).
• Calculating the centroids (precise centers) of astronomical sources.
• Performing "isophotal analysis" (measuring shapes of galaxies).
• Segmentation of images based on thresholding.

Reference Documentation

Official docs: https://photutils.readthedocs.io/
GitHub: https://github.com/astropy/photutils
Search patterns: photutils.aperture, photutils.detection, photutils.background, photutils.psf