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Star-Forming Radio Galaxies

Finding Targets

An object whose ANCILLARY_TARGET1 value include one or more of the bitmasks in the following table was targeted for spectroscopy as part of this ancillary target program. See SDSS-III bitmasks to learn how to use these values to identify objects in this ancillary target program.

Primary Program Sub-program
(bit name)
Bit Number Target density
Survey Area
Star Forming Radio Galaxies BLUE_RADIO 56 0.4 10,000


Joint analysis of SDSS, FIRST, and the NRAO VLA Sky Survey (NVSS; Condon et al. 1998) has shown that low redshift radio AGNs play an essential role in regulating the growth of massive galaxies (e.g. Best et al. 2005, 2007). However, much less is known about the detailed interplay of gas cooling and radio feedback in more luminous radio galaxies at higher redshifts. Current samples are incomplete, in particular for radio galaxies with significant on-going star formation.

Target Selection Details

This ancillary program selects radio galaxies with blue colors at z > 0.3 that would otherwise be missed from the LOWZ and CMASS samples. Galaxy targets were selected from DR7 according to the following criteria:

The last criterion is designed to color-select objects at z > 0.3. We cross-matched this sample with the FIRST catalog (July 2008 version) and selected all objects within 3" of FIRST sources with fluxes > 3.5 mJy. Most targets were within 1.5". Finally, we rejected objects spectroscopically observed by SDSS-I/II, and objects meeting the target selection criterion for the galaxy samples. In total there were 4610 targets; we randomly sampled these to produce a final list of 4170 ancillary targets.

Primary contact

Guinevere Kauffmann
gkauffmann -at-

Other contacts

Christy Tremonti, Tim Heckman, Kevin Bundy, Yen-Ting Lin, Yan-Mei Chen


Condon, J. J., et al., 1998, AJ, 115, 1693 doi:10.1086/300337
Best, P. N., et al., 2005, MNRAS, 362, 25
Best, P. N., et al., 2007, MNRAS, 379, 894