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J/AJ/139/390   Optically selected BL Lac objects from SDSS-DR7  (Plotkin+, 2010)

Optically selected BL Lacertae candidates from the Sloan Digital Sky Survey data release seven. Plotkin R.M., Anderson S.F., Brandt W.N., Diamond-Stanic A.M., Fan X., Hall P.B., Kimball A.E., Richmond M.W., Schneider D.P., Shemmer O., Voges W., York D.G., Bahcall N.A., Snedden S., Bizyaev D., Brewington H., Malanushenko V., Malanushenko E., Oravetz D., Pan K., Simmons A. <Astron. J., 139, 390-414 (2010)> =2010AJ....139..390P
ADC_Keywords: BL Lac objects ; QSOs ; Active gal. nuclei ; Photometry, SDSS ; Redshifts Keywords: BL Lacertae objects: general - galaxies: active - quasars: general - surveys Abstract: We present a sample of 723 optically selected BL Lac candidates from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) spectroscopic database encompassing 8250deg2 of sky; our sample constitutes one of the largest uniform BL Lac samples yet derived. Each BL Lac candidate has a high-quality SDSS spectrum from which we determine spectroscopic redshifts for ∼60% of the objects. Redshift lower limits are estimated for the remaining objects utilizing the lack of host galaxy flux contamination in their optical spectra; we find that objects lacking spectroscopic redshifts are likely at systematically higher redshifts. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table5.dat 109 637 Observed parameters of radio-Loud BL Lac candidates table6.dat 109 86 Observed parameters of weak-featured radio-quiet objects table7.dat 91 637 Derived parameters of radio-loud BL Lac candidates table8.dat 91 86 Derived parameters of weak-featured radio-quiet objects
See also: VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010) J/AJ/129/2542 : BL Lac from SDSS (Collinge+, 2005) J/AJ/135/2453 : Sample of BL Lac objects from SDSS and FIRST (Plotkin+, 2008) Byte-by-byte Description of file: table[56].dat
Bytes Format Units Label Explanations
1- 18 A18 --- SDSS SDSS source name (HHMMSS.ss+DDMMSS.s) (1) 20- 28 F9.5 deg RAdeg Right ascension (J2000) 30- 38 F9.5 deg DEdeg Declination (J2000) 40 A1 --- Cl [HL] High or Low-confidence Classification (2) 42 A1 --- NB [NY] Object appears as NED BL Lac object? (3) 44- 48 F5.2 mag umag SDSS u-band apparent magnitude 50- 54 F5.2 mag gmag SDSS g-band apparent magnitude 56- 60 F5.2 mag rmag SDSS r-band apparent magnitude 62- 66 F5.2 mag imag SDSS i-band apparent magnitude 68- 72 F5.2 mag zmag SDSS z-band apparent magnitude 74- 78 F5.3 --- zsp ? Spectroscopic redshift 80 A1 --- q_zsp [LRTU] Redshift reliability (4) 82- 87 F6.3 --- C ? CaII H/K break strength 89- 93 F5.2 --- alpha Optical spectral index referenced at 616.5nm αν 95-109 A15 --- Comments ? Additional comments (5)
Note (1): IAU Designation (J2000): SDSS JHHMMSS.SS+DDMMSS.S. Note (2): Classification as follows: H = high-confidence BL Lac candidate L = low-confidence BL Lac candidate (see text) Note (3): Flag as follows: N = not listed as a BL Lac object in NED Y = listed as a BL Lac object in NED. Note, not all previously identified SDSS BL Lac candidates are listed as BL Lac objects in NED Note (4): Redshift flag as follows: L = redshift is a lower limit from a MgII absorption doublet R = reliable redshift T = tentative redshift U = unknown redshift Note (5): Codes as follows: C05 = appears as an SDSS BL Lac candidate in Collinge et al. (2005, Cat. J/AJ/129/2542) A07 = appears as an SDSS BL Lac candidate in Anderson et al. (2007, Cat. J/AJ/133/313) P08 = appears as an SDSS BL Lac candidate in Plotkin et al. (2008, Cat. J/AJ/135/2453) S09 = appears as a high-z weak-line quasar is Shemmer et al. (2009, Cat. J/ApJ/696/580) D09 = appears as a high-z weak-line quasar in Diamond-Stanic et al. (2009, Cat. J/ApJ/699/782)
Byte-by-byte Description of file: table[78].dat
Bytes Format Units Label Explanations
1- 18 A18 --- SDSS SDSS source name (JHHMMSS.ss+DDMMSS.s) (1) 20- 24 F5.3 --- zsp ? Spectroscopic redshift (2) 26- 30 F5.3 --- zgal ? Host galaxy redshift limit (6) 32- 36 F5.2 mag FAGN AGN component apparent magnitude (7) 38- 43 F6.3 [10-7W/Hz] logLo Log AGN component optical specific luminosity (8) 45 A1 --- f_F1.4 [FNUX] Radio flag, U=upper limit (9) 47- 54 F8.3 mJy F1.4 ? Radio flux density at observed-frame 1.4GHz (10) 56- 61 F6.3 [10-7W/Hz] logLr ? Log radio specific luminosity (11) 63 A1 --- f_FX [RU] X-ray flag, U=upper limit (12) 65- 71 F7.3 10-16W/m2 FX Unabsorbed X-ray flux in 10^-13^erg/scm^2^ (13) 73- 78 F6.3 [10-7W/Hz] logLX Log X-ray specific luminosity (14) 80- 85 F6.3 --- a(ro) ? Radio-optical spectral index alpha_ro_ (15) 87- 91 F5.3 --- a(oX) Optical-X-ray spectral index alpha_oX_ (16)
Note (1): IAU designation (J2000): SDSS JHHMMSS.ss+DDMMSS.s. Note (2): Redshift derived from SDSS spectrum. Note (6): Lower limit to redshift of objects with unknown spectroscopic redshifts, derived from the lack of host galaxy contamination to their SDSS spectra (see Section 5.2.1). Note (7): In the filter closest to 500nm rest-frame, assuming redshift limits are exact. This magnitude is corrected for Galactic extinction (using the Schlegel et al. 1998ApJ...500..525S dust maps), and contamination from the host galaxy is removed when necessary (see Section 5.2.2). Note (8): At 500nm rest-frame, excluding the host galaxy (see Section 5.2.2). Note (9): Radio flag as follows: F = radio information comes from the FIRST radio survey. N = radio information comes from the NVSS radio survey. U = source is not detected in the radio by FIRST or NVSS. Radio information are upper limits derived from the FIRST detection threshold (see Section 5.3.1). X = source is not detected in the radio by NVSS, and it is outside of the FIRST footprint. No radio information is included for these sources. Note (10): This is an upper limit if the radio flag is set to U and it is blank if the radio flag is set to X. Note (11): At rest-frame 5.0GHz, assuming a local radio spectral index of -0.27. This is an upper limit if the radio flag is set to U, and it is blank if the radio flag is set to X. Note (12): X-ray flag as follows: R = Source is detected in the X-ray by RASS U = Source is not detected in the X-ray by RASS. X-ray information are upper limits, derived from the RASS detection threshold (see Section 5.4.1). Note (13): From 0.1-2.4keV, corrected for Galactic absorption using the Stark et al. (1992, Cat. VIII/10) hydrogen maps and assuming an X-ray spectral index of 1.25. This is an upper limit if the X-ray flag is set to U. Note (14): At rest-frame 1keV. This is an upper limit if the X-ray flag is set to U. Note (15): At rest-frames 5GHz and 500nm in the radio and optical, respectively. This is an upper limit if the radio flag is set to U (and it is blank if the radio flag is set to X). Note (16): At rest-frames 500nm and 1keV in the optical and X-ray, respectively. This is a lower limit if the X-ray flag is set to U.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 14-May-2012
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