radio source

A radio source (RS, and within radio astronomy, sometimes just the word, source) is an object, or a location in the celestial sphere from which radio is detected. The term radio source avoids interpretation (i.e., any declaration what kind of object is producing the radio), though it is also often used even when a certain type of source is assumed. The Sun, Jupiter, and the galactic center are sources. Some other source types:

• radio stars.
• supernova remnants.
• star-forming regions.
• pulsars.
• rotating radio transients.
• radio galaxies.

In the case of galaxies, the word "source" may be used to indicate the location within the galaxy or adjacent to the galaxy (as in the case of radio stemming from jets) from which the radio signal is observed.

The terms extended source versus point source or unresolved source indicate whether it is resolved. The term giant radio source (GRS) may refer to the physical size of the source, which generally assumes at least some notion of the distance, or possibly may be based on the angular area across the celestial sphere.

The term GHz-peaked spectrum (GPS) refers to some extragalactic sources showing a peak in the gigahertz (microwave) range. They are presumed to be a type of active galactic nucleus (AGN).

Analogous terms are used for other bands, such as microwave source, infrared source (IR source), ultraviolet source (UV source), X-ray source, and gamma-ray source, and within context, the word source may mean any one of these.