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J/ApJ/649/63        DRaGONS survey                           (Schmidt+, 2006)

The DRaGONS survey: a search for high-redshift radio galaxies and heavily obscured active galactic nuclei. Schmidt S.J., Connolly A.J., Hopkins A.M. <Astrophys. J., 649, 63-78 (2006)> =2006ApJ...649...63S
ADC_Keywords: Surveys ; Galaxies, radio ; Infrared sources Keywords: galaxies: evolution - radio continuum: galaxies Abstract: We present the first results from the Distant Radio Galaxies Optically Non-detected in the SDSS (DRaGONS) survey. Using a novel selection technique for identifying high-redshift radio galaxy (HzRG) candidates, a large sample is compiled using bright (S1.4GHz>100mJy) radio sources from the FIRST survey having no optical counterpart in the SDSS. Near-IR K-band imaging for 96 targets allows preliminary identification of HzRG candidates through the well-known K-z relation, for subsequent spectroscopic observation. We measure magnitudes brighter than K∼19.5 for 70 of the 96, and limiting magnitudes for the remainder. Redshifts based on a linear fit to the K-z diagram give a mean <z≥2.5 and median z=2.0, showing that this method should be efficient at identifying a large number of HzRGs. Description: We acquired K-band images for 96 of the 172 unique candidates on the Kitt Peak National Observatory (KPNO) 4m Mayall telescope over two sets of four nights, 2003 April 2023 and 2004 May 31-June 3, using the Florida Multi-object Imaging Near-IR Grism Observational Spectrometer (FLAMINGOS) instrument. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 115 117 Detections table2.dat 88 34 Non-detections
See also: VIII/71 : The FIRST Survey Catalog, Version 03Apr11 (Becker+ 2003) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 10 A10 --- DRaGONS Object Name (JHHMM+DDMM) 11 A1 --- m_DRaGONS [abc] Multiplicity index on DRaGONS (G1) 13 A1 --- n_DRaGONS [c-g] Note on DRaGONS (1) 15- 24 A10 "YYYY/MM/DD" Date Observation Date 25- 27 A3 --- n_Date Second day of observation 29- 30 I2 h RAh ? Radio right ascension (J2000) (G2) 32- 33 I2 min RAm ? Radio right ascension (J2000) (G2) 35- 40 F6.3 s RAs ? Radio right ascension (J2000) (G2) 42 A1 --- DE- Radio declination sign (J2000) (G2) 43- 44 I2 deg DEd ? Radio declination (J2000) (G2) 46- 47 I2 arcmin DEm ? Radio declination (J2000) (G2) 49- 53 F5.2 arcsec DEs ? Radio declination (J2000) (G2) 55 A1 --- Ext? [YN] Extended source ? (G3) 57- 58 I2 h RAIh ? Infrared right ascension (J2000) 60- 61 I2 min RAIm ? Infrared right ascension (J2000) 63- 67 F5.2 s RAIs ? Infrared right ascension (J2000) 69 A1 --- DEI- Infrared declination sign (J2000) 70- 71 I2 deg DEId ? Infrared declination (J2000) 73- 74 I2 arcmin DEIm ? Infrared declination (J2000) 76- 80 F5.2 arcsec DEIs ? Infrared declination (J2000) 82- 88 F7.2 mJy Fpeak ? Peak 1.4GHz flux density from the FIRST (VIII/71) catalog 90- 96 F7.2 mJy Fint ? Integrated 1.4GHz flux density from the FIRST (VIII/71) catalog 97 A1 --- l_Kmag Limit flag on Kmag 98-102 F5.2 mag Kmag ? Apparent K magnitude for the infrared object (G4) 104-107 F4.2 mag e_Kmag ? rms uncertainty on Kmag (2) 109-111 F3.1 arcsec Seeing ? FWHM seeing measured for the field, for radio observations 112 A1 --- l_z Limit flag on z 113-115 F3.1 --- z ? Estimated redshift, for radio observations (3)
Note (1): Individual notes as follows: c = This object is an extended double lobe with a corresponding faint match in SDSS and should not have been included in our sample. The object has SDSS magnitudes g=23.25, r=22.29, i=21.26, and z=19.90. d = This object, 3C 257, was previously identified as a radio galaxy (Hewitt & Burbidge, 1991, Cat. VII/178). The K band contains Halpha emission, leading to the underestimate of redshift from the K-z diagram (for details see van Breugel et al., 1998ApJ...502..614V). e = This object is a wide-separation double lobe with several candidate objects along the radio axis. The probable match is faintly detected in SDSS with magnitudes of g=22.6, r=22.13, i=21.32 and z=20.27. f = Object J1411+0124 was observed on subsequent nights for a total integration time of 40 minutes. g = This object has a match in SDSS g=22.86, r=22.45, i=22.11, and z=21.12 and was improperly targeted because it is a weak double lobe. Note (2): Errors are those output by SExtractor. Note (3): Estimated redshift based on a fit to the Hubble K-z relation, given by K=4.62logz+17.2. For non-detections (Table 2), the estimated redshift is given as a lower limit for the 2σ limiting magnitude.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 10 A10 --- DRaGONS Object Name 11 A1 --- m_DRaGONS [abc] Multiplicity index on DRaGONS (G1) 13 A1 --- n_DRaGONS [h-i] Note on DRaGONS (1) 15- 30 A16 --- Date Observation Date 32- 33 I2 h RAh ? Radio right ascension (J2000) (G2) 35- 36 I2 min RAm ? Radio right ascension (J2000) (G2) 38- 43 F6.3 s RAs ? Radio right ascension (J2000) (G2) 45 A1 --- DE- Radio declination sign (J2000) (G2) 46- 47 I2 deg DEd ? Radio declination (J2000) (G2) 49- 50 I2 arcmin DEm ? Radio declination (J2000) (G2) 52- 56 F5.2 arcsec DEs ? Radio declination (J2000) (G2) 58 A1 --- Ext? [YN] Extended source ? (G3) 60- 65 F6.2 mJy Fpeak ? Peak 1.4GHz flux density from the FIRST (VIII/71) catalog 67- 72 F6.2 mJy Fint ? Integrated 1.4GHz flux density from the FIRST (VIII/71) catalog 74 A1 --- l_Kmag Limit flag on Kmag 75- 79 F5.2 mag Kmag ? 2sigma limit K magnitude for the infrared object (G4) 81- 83 F3.1 arcsec Seeing ? FWHM seeing measured for the field, for radio observations 85 A1 --- l_z Limit flag on z 86- 88 F3.1 --- z ? Estimated redshift, for radio observations (2)
Note (1): Individual notes as follows: h = J1350+0352 was observed on both 2003 April 20 and 2004 June 2, for a total integration time of 61 minutes with no detection. i = J2242-0808 was observed on two nights in 2004 for a total integration time of 29 minutes. Note (2): Estimated redshift based on a fit to the Hubble K-z relation, given by K=4.62logz+17.2. Here the estimated redshift is given as a lower limit for the 2sigma limiting magnitude.
Global notes: Note (G1): Objects with double-lobe and multiple radio morphologies have the infrared object reported first and the individual radio components named a, b, c as necessary. Objects identified as DRaGONS JHHMM+DDMMa in Simbad Note (G2): Position of radio detection from the FIRST catalog (J2000.0). Note (G3): Extended sources flag as follows: Y = if the object shows visible extension in the FIRST image or if the object is a double- or multiple-lobe radio source N = if the object is unresolved in the radio image Note (G4): Magnitudes are in the 2MASS system, which is slightly offset from the CIT system, given by Ks(2MASS)=K(CIT)+0.0000(J-K)CIT-0.024±0.003 (Carpenter, 2001AJ....121.2851C).
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 18-Jul-2008
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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