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- Ancillary Targets
- Transient Universe in Stripe 82
- Host Galaxies of SDSS-II SNe
- BCGs in
Stripe 82 - High-Quality LRG spectra
- Reddened
Quasars - No Quasar Left Behind
- Variability-Selected Quasars
- K-band Selected Quasars
- Low-Mass Stars and Brown Dwarfs
- Low-Mass Binary Stars
- White Dwarfs and Hot Subdwarfs
- Distant Halo
Giants - Bright
Galaxies - High-Energy Blazars in Optical
- An X-Ray View Star Formation
- Remarkable X-Ray Sources
- Star-Forming Radio Galaxies
- Galaxies Near QSO Sight Lines
- Luminous Blue Galaxies
- BAL Quasar Variability
- Variable QSO Absorption
- Double-Lobed Radio QSOs
- High-Redshift Quasars
- High-z QSOs in SDSS/UKIDSS
- BOSS Targeting
- Algorithms
K-Band Selected Sample of Quasars
Summary
Quasar candidates in the 220-square-degree footprint of Stripe 82 that were selected by matching SDSS and UKIDSS photometry
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.
| Program (bit name) |
Bit in ANCILLARY_TARGET2 | Target Description | Target density (deg–2) |
|---|---|---|---|
| KQSO_BOSS | 2 | Quasars selected from UKIDSS photometry | 1 |
Description
Potential quasars were identified by photometering data from the UKIRT Infrared Deep Sky Survey (UKIDSS) at the position of SDSS sources to a limiting magnitude KAB < 19.0 (KVega < 17.1). The goal of this ancillary target program was to identify highly red and reddened quasars that would have been missed by the main BOSS Quasar Target Selection algorithms. The sample described here allows investigations of, for example, the incidence of broad absorption line (BAL) quasars, or of highly reddened gravitationally-lensed quasars.
This ancillary target program superseded the Reddened Quasars target selection program, since the superior UKIDSS photometry could target red, reddened, and high-redshift quasars better than 2MASS photometry. In addition, the color cut of (uPSF - gPSF) > 0.4 used here better complemented the BOSS mission to target mostly higher-redshift quasars.
The targets not included in Stripe 82 were effectively incorporated into the BONUS sample through the XDQSO target selection (Bovy et al. 2011, Bovy et al. 2012); therefore, this ancillary program will not be continued for the remainder of the BOSS footprint.
This ancillary program superseded the ancillary program A Large Sample of Reddened Quasars>, as the superior UKIDSS photometry could better target red, reddened and high redshift quasars than 2MASS. In addition, the cut of (uPSF - gPSF) > 0.4 better complemented the BOSS mission to target mostly higher redshift quasars.
Primary contact
| Richard McMahon |
|---|
| University of Cambridge |
| rgm -at- ast.cam.ac.uk |
Target selection details
In the original selection, approximately 2,000 targets were identified that have (gPSF - iPSF) < 1.153 x (iPSF - K) - 1.401, to avoid the color space locus of the stellar main sequence, and (uPSF - gPSF) > 0.4 to exclude UV-excess quasars (i.e., unreddened quasars at redshifts of about z > 2.15).
References
Bovy, J., Hennawi, J.F., Hogg, D.W., Myers, A.D., Kirkpatrick, J.A., Schlegel, D.J.,
Ross, N.P., Sheldon, E.S., McGreer, I.D., Schneider, D.P., & Weaver, B.A., 2011, ApJ, 729, 141,
doi:10.1088/0004-637X/729/2/141
Bovy, J., Myers, A.D., Hennawi, J.F., Hogg, D.W., McMahon, R.G.,
Schiminovich, D., Sheldon, E.S., Brinkmann, J., Schneider, D.P., & Weaver, B.A.,
2012, ApJ, 749, 41,
doi:10.1088/0004-637X/749/1/41