Radprofile

Radprofile, short for radial profile, is a concept used in astronomy and image analysis to describe how a quantity changes with distance from a central point. In its common usage, radprofile refers to the azimuthally averaged radial distribution of a quantity such as surface brightness in an astronomical image. By selecting a center and computing the mean or median value in a series of concentric annuli (and optionally elliptical annuli to account for a galaxy’s shape), one obtains a one-dimensional curve I(r) as a function of radius r. This profile can reveal the structural properties of objects, such as the concentration of light and the presence of bulges, disks, or halos.

In practice, generating a radprofile involves several steps. A center must be defined, after which photometric measurements are performed in a set of annuli that may be circular or elliptical. Background subtraction, mask handling, and noise estimation are commonly applied. The resulting profile is often normalized by total flux or by a characteristic radius. Radprofiles are used to fit simple or composite models, such as exponential disks or Sérsic profiles, to quantify structure with parameters like effective radius and concentration. They also support comparisons across bands, wavelengths, or different epochs.

Implementation and interpretation: Radprofiles can be produced with astronomy software and programming libraries, including Python tools such as Photutils and Astropy. Uncertainties are typically estimated from photon statistics, background noise, or resampling methods. Limitations include sensitivity to center position, isophotal shape assumptions, PSF effects, and contamination from foreground stars or neighboring sources. Proper masking and, when necessary, PSF deconvolution are important for reliable interpretation.

See also:

- surface brightness profile

- Sérsic profile

- exponential disk

- PSF (point spread function)

- Photutils

- Astropy