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J/AJ/153/107  Australian Dark Energy Survey (OzDES) quasar catalog  (Tie+, 2017)

A study of quasar selection in the supernova fields of the Dark Energy Survey. Tie S.S., Martini P., Mudd D., Ostrovski F., Reed S.L., Lidman C., Kochanek C., Davis T.M., Sharp R., Uddin S., King A., Wester W., Tucker B.E., Tucker D.L., Buckley-Geer E., Carollo D., Childress M., Glazebrook K., Hinton S.R., Lewis G., Macaulay E., O'Neill C.R., Abbott T.M.C., Abdalla F.B., Annis J., Benoit-Levy A., Bertin E., Brooks D., Carnero Rosell A., Carrasco Kind M., Carretero J., Cunha C.E., da Costa L.N., DePoy D.L., Desai S., Doel P., Eifler T.F., Evrard A.E., Finley D.A., Flaugher B., Fosalba P., Frieman J., Garcia-Bellido J., Gaztanaga E., Gerdes D.W., Goldstein D.A., Gruen D., Gruendl R.A., Gutierrez G., Honscheid K., James D.J., Kuehn K., Kuropatkin N., Lima M., Maia M.A.G., Marshall J.L., Menanteau F., Miller C.J., Miquel R., Nichol R.C., Nord B., Ogando R., Plazas A.A., Romer A.K., Sanchez E., Santiago B., Scarpine V., Schubnell M., Sevilla-Noarbe I., Smith R.C., Soares-Santos M., Sobreira F., Suchyta E., Swanson M.E.C., Tarle G., Thomas D., Walker A.R., (The DES Collaboration) <Astron. J., 153, 107-107 (2017)> =2017AJ....153..107T (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts ; Photometry, ugriz ; Photometry, infrared Keywords: quasars: general Abstract: We present a study of quasar selection using the supernova fields of the Dark Energy Survey (DES). We used a quasar catalog from an overlapping portion of the SDSS Stripe 82 region to quantify the completeness and efficiency of selection methods involving color, probabilistic modeling, variability, and combinations of color/probabilistic modeling with variability. In all cases, we considered only objects that appear as point sources in the DES images. We examine color selection methods based on the Wide-field Infrared Survey Explorer (WISE) (Wright et al. 2010AJ....140.1868W) mid-IR W1-W2 color, a mixture of WISE and DES colors (g-i and i-W1), and a mixture of Vista Hemisphere Survey (McMahon et al. 2013Msngr.154...35M) and DES colors (g-i and i-K). For probabilistic quasar selection, we used XDQSO, an algorithm that employs an empirical multi-wavelength flux model of quasars to assign quasar probabilities. Our variability selection uses the multi-band χ2-probability that sources are constant in the DES Year 1 griz-band light curves. The completeness and efficiency are calculated relative to an underlying sample of point sources that are detected in the required selection bands and pass our data quality and photometric error cuts. We conduct our analyses at two magnitude limits, i<19.8 mag and i<22 mag. For the subset of sources with W1 and W2 detections, the W1-W2 color or XDQSOz method combined with variability gives the highest completenesses of >85% for both i-band magnitude limits and efficiencies of >80% to the bright limit and >60% to the faint limit; however, the giW1 and giW1+variability methods give the highest quasar surface densities. The XDQSOz method and combinations of W1W2/giW1/XDQSOz with variability are among the better selection methods when both high completeness and high efficiency are desired. We also present the OzDES Quasar Catalog of 1263 spectroscopically confirmed quasars from three years of OzDES observation in the 30 deg2 of the DES supernova fields. The catalog includes quasars with redshifts up to z∼4 and brighter than i=22 mag, although the catalog is not complete up to this magnitude limit. Description: The Australian Dark Energy Survey (OzDES; Yuan et al. 2015MNRAS.452.3047Y) is a spectroscopic survey of the DES supernova fields using the AAOmega spectrograph (Smith et al. 2004SPIE.5492..410S) on the Anglo-Australian Telescope (AAT). The field of view of the AAT multi-object fiber-positioning system (Lewis et al. 2002MNRAS.333..279L) is well matched to DECam, making the AAT a well-suited spectroscopic follow-up instrument for DES. OzDES commenced observations at the same time as DES in 2013B and aims to measure redshifts for thousands of host galaxies of Type Ia supernovae and black hole masses for hundreds of AGNs and quasars (King et al. 2015MNRAS.453.1701K) using reverberation mapping (Blandford & McKee 1982ApJ...255..419B; Peterson 1993PASP..105..247P). The observing targets and results of OzDES observations are compiled into a spectroscopic catalog known as the Global Redshift Catalog (GRC). The GRC is updated after every OzDES observing season. In this work, we used the 2016 February version of the OzDES GRC. Here we present the OzDES Quasar Catalog of 1263 OzDES sources with Mi←22 mag and i<22 mag that are spectroscopically confirmed quasars. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 522 1263 OzDES quasar catalog
See also: III/250 : The VIMOS VLT deep survey (VVDS-DEEP) (Le Fevre+ 2005) II/328 : AllWISE Data Release (Cutri+ 2013) J/MNRAS/472/273 : OzDES DR1 (Childress+, 2017) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 21 A21 --- ID OzDES Global Redshift Catalog identifier 23- 32 I10 --- DES [3167323870/3174409350] DES identifier (1) 34- 45 E12.6 deg RAdeg Right Ascension in decimal degrees (J2000) 47- 59 E13.6 deg DEdeg Declination in decimal degrees (J2000) 61- 72 E12.6 --- z OzDES spectroscopic redshift 74- 86 E13.6 mag iMag Absolute i band magnitude using z 88- 99 E12.6 mag gmag ?=99 Apparent DES g band AB magnitude (2) (3) 101-112 E12.6 mag rmag ?=99 Apparent DES r band AB magnitude (2) (3) 114-125 E12.6 mag imag Apparent DES i band AB magnitude (2) 127-138 E12.6 mag zmag ?=99 Apparent DES z band AB magnitude (2) (3) 140-151 E12.6 mag Ymag ?=99 Apparent DES Y band AB magnitude (2) (3) 153-164 E12.6 mag e_gmag ?=99 Uncertainty in gmag (3) 166-177 E12.6 mag e_rmag ?=99 Uncertainty in rmag (3) 179-190 E12.6 mag e_imag Uncertainty in imag 192-203 E12.6 mag e_zmag ?=99 Uncertainty in zmag (3) 205-216 E12.6 mag e_Ymag ?=99 Uncertainty in Ymag (3) 218 I1 --- f_gmag [0/3] SExtractor flag for gmag 220 I1 --- f_rmag [0/4] SExtractor flag for rmag 222 I1 --- f_imag [0/6] SExtractor flag for imag 224 I1 --- f_zmag [0/6] SExtractor flag for zmag 226 I1 --- f_Ymag [0/3] SExtractor flag for Ymag 228-240 E13.6 --- gmod DES spread_model from SExtractor in g band (4) 242-254 E13.6 --- rmod DES spread_model from SExtractor in r band (4) 256-268 E13.6 --- imod DES spread_model from SExtractor in i band (4) 270-282 E13.6 --- zmod DES spread_model from SExtractor in z band (4) 284-296 E13.6 --- Ymod DES spread_model from SExtractor in Y band (4) 298-309 E12.6 --- e_gmod Uncertainty in gmod 311-322 E12.6 --- e_rmod Uncertainty in rmod 324-335 E12.6 --- e_imod Uncertainty in imod 337-348 E12.6 --- e_zmod Uncertainty in zmod 350-361 E12.6 --- e_Ymod Uncertainty in Ymod 363-374 E12.6 mag W1mag ?=99 WISE/W1 3.4µm band Vega magnitude (3) (5) 376-387 E12.6 mag W2mag WISE/W2 4.6µm band Vega magnitude (5) 389-400 E12.6 mag e_W1mag ?=99 Uncertainty in W1mag (3) 402-413 E12.6 mag e_W2mag ?=99 Uncertainty in W2mag (3) 415-426 E12.6 mag ymag ?=99 VHS y band Vega magnitude (3) (6) 428-439 E12.6 mag Jmag ?=99 VHS J band Vega magnitude (3) (6) 441-452 E12.6 mag Hmag ?=99 VHS H band Vega magnitude (3) (6) 454-466 E13.6 mag Ksmag ?=99 VHS Ks band Vega magnitude (3) (6) 468-479 E12.6 mag e_ymag ?=99 Uncertainty in ymag (3) 481-492 E12.6 mag e_Jmag ?=99 Uncertainty in Jmag (3) 494-505 E12.6 mag e_Hmag ?=99 Uncertainty in Hmag (3) 507-518 E12.6 mag e_Ksmag ?=99 Uncertainty in Ksmag (3) 520-522 I3 --- Code [0/309] OzDES selection code (7)
Note (1): From the Y1A1COADDOBJECTS_DFULL catalog. Note (2): See Section 2.1. Note (3): Quasars with non-detections in DES bands, no WISE matches, or no VHS matches have entries of 99 for their magnitudes and errors. Note (4): See Section 4. Note (5): From the ALLWISE Catalog (Cutri et al. 2013, Cat. II/328; see Section 2.3). Note (6): From the DR3 vhsSource catalog (; see Section 2.2). Note (7): The OzDES selection codes note how the quasars were initially selected for OzDES observations. For instance, the codes are as follows: 0 = Not targeted as a quasar candidate; 1 = DES Science Verification (SV, Banerji et al. 2015MNRAS.446.2523B) target; 2 = VIMOS-VLT Deep Survey (VVDS, Le Fevre et al. 2005, Cat. III/250) quasar; 4 = QSO selection using the LePhare photo-z estimation tool (Arnouts et al. 1999MNRAS.310..540A); 8 = i<21.5 + giK selection (see Section 5.3) + KVega>14 + W1-W2>0.7; 16 = NED quasar (; 32 = giW1 selection (see Section 5.2); 64 = Similar selection to code 8 but with a relaxed blue cut in giK; 128 = High redshift selection using gri and riz colors; 256 = u-band selection.
History: From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 04-Jul-2017
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