# A-PHOT: a new, versatile code for precision aperture photometry

## TL;DR

A-PHOT is a versatile, publicly available code for aperture photometry that enables precise flux and morphological measurements on astronomical images, especially suited for multi-band extragalactic surveys and forced photometry tasks.

## Contribution

It introduces a new photometry code that performs measurements on predefined positions, estimates morphological parameters, and optimizes apertures for maximum signal-to-noise ratio, enhancing accuracy and flexibility.

## Key findings

- Good agreement with existing survey catalogs
- Accurate flux and morphological measurements on synthetic data
- Effective performance on real astronomical images

## Abstract

We present A-PHOT, a new publicly available code for performing aperture photometry on astronomical images, that is particularly well suited for multi-band extragalactic surveys. A-PHOT estimates the fluxes emitted by astronomical objects within a chosen set of circular or elliptical apertures. Unlike other widely used codes, it runs on predefined lists of positions, allowing for repeated measurements on the same list of objects on different images. This can be very useful when forced photometric measurement on a given position is needed. A-PHOT can also estimate morphological parameters and a local background flux, and compute on-the-fly individual optimized elliptical apertures, in which the signal-to-noise ratio is maximized. We check the performance of A-PHOT on both synthetic and real test datasets: we explore a simulated case of a space-based high-resolution imaging dataset, investigating the input parameter space to optimize the accuracy of the performance, and we exploit the CANDELS GOODS-South data to compare the A-PHOT measurements with those from the survey legacy catalogs, finding good agreement overall. A-PHOT proves to a useful and versatile tool for quickly extracting robust and accurate photometric measurements and basic morphological information of galaxies and stars, with the advantage of allowing for various measurements of fluxes at any chosen position without the need of a full detection run, and for determining the basic morphological features of the sources.