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Double-lobed Radio Quasars


Spectra of point-source objects near the midpoint of a double-lobed radio quasar in FIRST

Finding Targets

An object whose ANCILLARY_TARGET2 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.

(bit name)
Bit in ANCILLARY_TARGET2 Target Description Target density
RADIO_2LOBE_QSO 5 Object near the midpoint of a double-lobed object identified in FIRST 0.08


Objects identified as optical point sources near the midpoint of pairs of FIRST radio sources are observed as potential double-lobed radio quasars. Such quasars are important for studying quasar evolution and interactions of radio jets with their local environment.

Primary contact

Amy Kimball
Amy.Kimball -at-

Target Selection Details

Candidates are selected by identifying FIRST pairs with a separation less than 60" and no SDSS optical counterpart within 2" of either source. SDSS point sources located within a search radius that ranges between 2" and 5.3" (depending on the separation distance of the FIRST pair) from the midpoint are targeted. FIRST pairs with a flux ratio > 10 are rejected because true double-lobed sources are unlikely to have a high ratio of lobe-lobe flux density. The final catalog includes objects not spectroscopically observed with SDSS, not targeted in the main BOSS sample, and with 17.8 < i < 21.6 (Galactic extinction-corrected).