![[EXT]](images/offsite.png)
- 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
No Quasar Left Behind
Summary
An attempt to find all likely quasars in the 220-square-degree footprint of SDSS Stripe 82, selecting based only on variable source light curve data.
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) |
|---|---|---|---|
| QSO_VAR | 3 | Likely quasar selected by "No Quasar Left Behind" program | 6.0 |
Description
We observed unresolved sources that had not been previously observed in SDSS spectroscopy that exhibit photometric variability statistically similar to that of spectroscopically confirmed quasars. Out of 11,000 variable sources with 16.2 < iPSF < 20.5, we selected 1,500 targets identified using the technique outlined in Butler & Bloom (2011). The sample complements the sample from the ancillary product Variability Selected Quasars, but targets brighter objects without color cuts, thus leading to a higher density of lower-redshift quasars.
The adopted variability-based selection criteria correctly identify 96 percent of previously known quasars. Overall, than 80 percent of these ancillary targets are expected to be quasars in the redshift range 0 < z < 5.
The brightest of these targets (iPSF < 19) were observed to test the completeness of the color-selected SDSS sample (Ross et al. 2011). The fainter subset represents a nearly complete sample that was selected from uniform photometry. In addition, this ancillary target program provides an invaluable training sample for optimizing quasar selection algorithms based on photometric variability, which will be vital for planning future synoptic surveys.
Primary contact
| Nat Butler |
|---|
| Arizona State University |
| natbutler -at- asu.edu |
Other contacts
Nic Ross, Željko Iveziić, Chelsea MacLeod, Amy Kimball, Scott Anderson, Rob Gibson, Neil Brandt, Michael Strauss
REFERENCES
Butler, N. R. & Bloom, J. S. 2011, AJ, 141, 93
Ross, A. J., et al. 2011, MNRAS, 417, 1350