NED Abstract 
Copyright by American Astronomical Society.
Reproduced by permission

2011ApJ...742...49T

Variable and Transient Radio Sources in the FIRST Survey

Thyagarajan, Nithyanandan; Helfand, David J.; White, Richard L.; Becker,
Robert H.

Abstract. A comprehensive search for variable and transient radio sources
has been conducted using ~55,000 snapshot images of the Faint Images of
the Radio Sky at Twenty-cm survey. We present an analysis leading to the
discovery of 1627 variable and transient objects down to mJy levels over a
wide range of timescales (a few minutes to years). Variations observed
range from 20% to a factor of 25. Multi-wavelength matching for
counterparts reveals the diverse classes of objects exhibiting
variability, ranging from nearby stars and pulsars to galaxies and distant
quasars. Interestingly, more than half of the objects in the sample have
either no classified counterparts or no corresponding sources at any other
wavelength and require multi-wavelength follow-up observations. We discuss
these classes of variables and speculate on the identity of objects that
lack multi-wavelength counterparts. 

Key words: catalogs, methods: data analysis, methods: statistical, radio
continuum: general, surveys