cphot

cphot is an open-source software package designed to perform photometry on astronomical images. It provides tools for both aperture photometry and point-spread function (PSF) fitting, as well as routines for background estimation, source detection, and photometric calibration against standard stars. The package aims to offer accurate flux measurements in both sparse and crowded fields and supports data from a range of instruments.

The software supports input in FITS format, optional world coordinate system alignment, and multi-band datasets. It outputs fluxes and magnitudes with uncertainties, along with quality flags and optional aperture corrections. cphot includes a scripting interface for batch processing and can be used in automated data pipelines; Python bindings are available for integration into analysis workflows.

Core features include automatic source detection, PSF model generation from selected stars, iterative PSF fitting in crowded regions, and optional aperture photometry. It also implements background estimation, deblending of overlapping sources, and photometric calibration using standard-star observations, with support for zero-point, extinction, and color-term corrections.

Development and licensing: cphot is maintained by an open community of contributors and distributed under an open-source license. It emphasizes portability across operating systems and interoperability with other astronomical software. While not tied to a single institution, it is commonly used in academic research and teaching to illustrate practical photometry techniques.

See also: photometry, PSF photometry, aperture photometry, DAOPHOT, DOLPHOT.