J/AJ/153/157 Candidate ICRF flat-spectrum radio sources. III. (Titov+, 2017)
Optical spectra of candidate International Celestial Reference Frame (ICRF)
flat-spectrum radio sources. III.
Titov O., Pursimo T., Johnston H.M., Stanford L.M., Hunstead R.W.,
Jauncey D.L., Zenere K.A.
<Astron. J., 153, 157-157 (2017)>
=2017AJ....153..157T 2017AJ....153..157T (SIMBAD/NED BibCode)
ADC_Keywords: Radio sources ; QSOs ; Galaxies, radio ; BL Lac objects ;
Spectroscopy ; Redshifts ; VLBI
Keywords: BL Lacertae objects: general - galaxies: active -
quasars: emission lines - radio continuum: general - reference systems
Abstract:
In extending our spectroscopic program, which targets sources drawn
from the International Celestial Reference Frame (ICRF) Catalog, we
have obtained spectra for ∼160 compact, flat-spectrum radio sources
and determined redshifts for 112 quasars and radio galaxies. A further
14 sources with featureless spectra have been classified as BL Lac
objects. Spectra were obtained at three telescopes: the 3.58m European
Southern Observatory New Technology Telescope, and the two 8.2m Gemini
telescopes in Hawaii and Chile. While most of the sources are powerful
quasars, a significant fraction of radio galaxies is also included
from the list of non-defining ICRF radio sources.
Description:
Spectroscopic observations were carried out at three optical
facilities.
We had a five-night observing run in Visitor Mode at the ESO 3.58m New
Technology Telescope (NTT) in 2013 December (Proposal 092.A-0021 (A))
using the ESO Faint Object Spectrograph and Camera system with grism
#13 covering the wavelength range 3685-9315Å. The seeing during
observations was typically 0.5''-2.0'', with a spectral resolution of
21Å FWHM. Exposure times varied from 5 to 30 minutes depending on
the magnitude of each target and current sky conditions. Wavelength
calibration made use of HeNeAr comparison spectra, resulting in an rms
accuracy of 0.5Å.
A large number of targets were observed in Service Mode at the Gemini
North and Gemini South 8.2m telescopes through the Poor Weather
Program (Proposals GN-2012B-Q-127, GS-2013A-Q-99, GS-2014A-Q-93) using
the Gemini Multi-Object Spectrograph (GMOS) system with grating R400
at each site. This grating covers 4500Å centered at 5200Å. The
wavelength resolution was ∼15Å FWHM, and an exposure time of 20
minutes was used for all targets. Wavelength calibration used the
spectra of a CuAr comparison lamp, giving an rms accuracy of 0.3Å.
We present our spectroscopic results in the same format as our
previous paper (Titov et al. 2013, Cat. J/AJ/146/10). The redshifts of
112 IVS objects are listed in Table1.
Fourteen objects with good S/N and featureless spectra were classified
as probable BL Lac objects. These objects are listed in Table2.
An additional 23 targets had low S/N spectra that did not permit a
confident spectral classification. These are listed in Table3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 13 110 Observed IVS objects
table1.dat 89 401 Observed emission lines
table2.dat 48 14 Probable BL Lac objects
table3.dat 48 22 Objects with low signal-to-noise spectra
notes.dat 415 33 Notes on individual targets
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See also:
VII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)
I/323 : International Celestial Reference Frame 2, ICRF2 (Ma+, 2009)
J/AJ/150/58 : VLBI ICRF2 (Fey+, 2015)
J/AJ/146/10 : Spectroscopy of emission-line ICRF2 candidates (Titov+, 2013)
J/A+A/559/A95 : Fitted proper motions for the DR solution (Titov+, 2013)
J/A+A/529/A91 : Proper motions of 555 quasars from VLBI (Titov+, 2011)
J/A+A/506/1477 : Radio source distribution (Titov+, 2009)
Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [IVS B]
6- 13 A8 --- IVS International VLBI Service name (HHMM+DDd, B1950)
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Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- --- [IVS B]
6- 13 A8 --- IVS International VLBI Service name (HHMM+DDd, B1950)
15- 16 I2 h RAh Hour of Right Ascension (J2000) (G1)
18- 19 I2 min RAm Minute of Right Ascension (J2000) (G1)
21- 27 F7.4 s RAs Second of Right Ascension (J2000) (G1)
29 A1 --- DE- Sign of the Declination (J2000) (G1)
30- 31 I2 deg DEd Degree of Declination (J2000) (G1)
33- 34 I2 arcmin DEm Arcminute of Declination (J2000) (G1)
36- 41 F6.3 arcsec DEs Arcsecond of Declination (J2000) (G1)
43- 45 A3 --- Tel Abbreviation of the telescope used for the
spectrum (GS, GN, or NTT) (G2)
47- 56 A10 --- Line Line identifier
58- 63 F6.1 0.1nm Rlambda [1025.7/5175] Rest wavelength λ (in Å)
65- 70 F6.1 0.1nm Olambda [3730.5/9015.2] Observed wavelength λ
(in Å)
71 A1 --- f_Olambda []] Flag ']' on Olambda when the line was not
used for redshift determination
73- 78 F6.4 --- [0.227/3.3] Mean spectroscopic redshift
80- 85 F6.4 --- e_ [0.0001/0.013] Uncertainty in z (1)
87 A1 --- f_ [S] Flag indicating a single-line redshift (2)
89 A1 --- n_IVS [N] Indicates a note in Section 3.1
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Note (1): The quoted errors in the mean redshift were calculated as discussed in
Titov et al. 2013 (Cat. J/AJ/146/10), i.e., from the quadratic combination
of the scatter in the redshift estimates and the fractional error in the
wavelength calibration.
Note (2): Single-line redshifts, usually Mg II, are assigned an uncertainty of
Δz=0.001 if the signal-to-noise ratio (S/N) is high, increasing to
0.003 for low S/N or a broad or asymmetric line.
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Byte-by-byte Description of file: table[23].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- --- [IVS B]
6- 13 A8 --- IVS International VLBI Service name (HHMM+DDd, B1950)
15- 16 I2 h RAh Hour of Right Ascension (J2000) (G1)
18- 19 I2 min RAm Minute of Right Ascension (J2000) (G1)
21- 27 F7.4 s RAs Second of Right Ascension (J2000) (G1)
29 A1 --- DE- Sign of the Declination (J2000) (G1)
30- 31 I2 deg DEd Degree of Declination (J2000) (G1)
33- 34 I2 arcmin DEm Arcminute of Declination (J2000) (G1)
36- 41 F6.3 arcsec DEs Arcsecond of Declination (J2000) (G1)
43- 48 A6 --- Tel Telescope abbreviation (GS, GN, or NTT) (G2)
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Byte-by-byte Description of file: notes.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- --- [IVS B]
6- 13 A8 --- IVS International VLBI Service name (HHMM+DDd, B1950)
15-415 A401 --- Note Notes on the source
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Global Notes:
Note (G1): Second Realization of the International Celestial Reference System
(ICRF2; Ma et al. 2009, Cat. I/323; Fey et al. 2015, Cat. J/AJ/150/58)
radio position.
Note (G2): The telescope codes are defined as follows:
GN = Gemini North;
GS = Gemini South;
NTT = ESO New Technology Telescope.
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History:
From electronic version of the journal
References:
Titov et al., Paper I. 2011AJ....142..165T 2011AJ....142..165T
Titov et al., Paper II. 2013AJ....146...10T 2013AJ....146...10T, Cat. J/AJ/146/10
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 01-Aug-2017