- 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
High Energy Blazars and Optical Counterparts of Gamma-ray Sources
Summary
A search for the optical counterparts of Fermi gamma-ray source in a 7,650 square degree area of sky
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.
Sub-program (bit name) |
Bit number | Target density (deg–2) |
---|---|---|
BLAZGRFLAT | 50 | 0.02 |
BLAZGRQSO | 51 | 0.02 |
BLAZGX | 52 | 0.01 |
BLAZGXQSO | 53 | 0.01 |
BLAZGXR | 54 | 0.03 |
BLAZXR | 55 | 0.11 |
Description
We targeted candidate optical counterparts of sources detected (or likely to be detected) by NASA's Fermi Gamma-ray Space Telescope (Atwood et al. 2009), with the goal to spectroscopically confirm and provide redshifts for candidate gamma-ray blazars.
Primary contact
Scott Anderson |
---|
University of Washington |
anderson -at- astro.washington.edu |
Other contacts
Toby Burnett
Target selection details
We require:
- Model magnitude < 21 in any of the three bandpasses g, r, or i.
- 3" fiber magnitudes > 16.5 (to minimize impact of fiber cross-talk).
Ranked in approximate order of priority, fibers are assigned to targets from the following subprograms:
- BLAZGXR: about 300 blazar candidates are assigned at highest priority to DR7 optical sources within Fermi gamma-ray error ellipses. Targets must also lie within the < 1' radius error circle for X-ray sources in the ROSAT All-Sky Survey (RASS) (Voges et al. 1999, 2000) and within 2" of a FIRST (Becker et al. 1995) radio source.
- BLAZGRFLAT: about 175 blazar candidates detected with Fermi and the Combined Radio All-Sky Targeted Eight GHz Survey (CRATES; Healey et al. 2007). Objects from the DR7 catalog within 2" of a CRATES radio source and within a Fermi error ellipse were targeted.
- BLAZGXQSO: 95 further candidate X-ray and gamma-ray emitting quasars/blazars, including photometric quasar/blazar candidates (Richards et al. 2009), as well as confirmed DR7 quasars/blazars (Schneider et al. 2010) revisited to assess optical spectral variability. Targets are selected that lie within < 1' of a RASS X-ray source and within Fermi error ellipses.
- BLAZGRQSO: 185 candidate radio and gamma-ray emitting quasars/blazars, including both photometric candidates (Richards et al. 2009), and DR7 confirmations (Schneider et al. 2010) revisited to assess optical spectral variability. Targets are selected that lie within 2" of a FIRST radio source and within Fermi error ellipses.
- BLAZGX: 75 targets that are candidate high-energy counterparts but which lack typical (e.g., radio emission, unusual optical color, etc.) blazar properties were targeted to probe unknown classes of gamma ray sources. The optically brightest objects from DR7 within the Fermi error ellipses and within 1' of a RASS X-ray source were preferentially targeted.
- BLAZXR: 1100 targets are selected that may plausibly emerge as Fermi sources, but are still below the detection limits in the early Fermi source catalogs. The approach is similar to the "ROSAT_A" target selection scheme described in Anderson et al. (2003) and the "pre-selection" approach of Healey et al. (2008) that provided many of the gamma-ray counterpart associations reported in the first Fermi catalogs (Abdo et al. 2010b,a). Targets are chosen from the DR7 photometry catalog with radio coincidence (within 2" of a FIRST source) and X-ray coincidence (< 1' of a RASS source). This sample overlaps heavily with the BONUS quasar sample, but includes quasars at lower redshift.
In addition, there were ten miscellaneous candidate blazar spectra taken in an early trial of this program. These targets were assigned subcategory names using the following flags: BLAZGVAR, BLAZR, and BLAZXRSAM.
REFERENCES
Atwood., W., B., et al., 2009, ApJ, 697, 1071
doi:10.1088/0004-637X/697/2/1071
Voges, W., et al, 1999, A&A, 349, 389
Voges, W., et al., 2000, IAU Circ., 7432, 1
Healey, S. E., et al, 2007, ApJS, 171, 61
doi:10.1086/513742
Richards, G. T., et al., 2009, ApJS, 180, 67
doi:10.1088/0067-0049/180/1/67
Schneider, D. P., et al., 2010, AJ, 139, 2360
doi:10.1088/0004-6256/139/6/2360
Anderson, S. F., et al., 2003, AJ, 126, 2209
doi:10.1086/378999
Abdo, A. A., et al, 2010a, ApJ, 715, 429
doi:10.1088/0004-637X/715/1/429
Abdo, A. A., et al, 2010b, ApJS, 188, 405
doi:10.1088/0067-0049/188/2/405