J/AJ/146/10 Spectroscopy of 120 emission-line ICRF2 candidates (Titov+, 2013)
Optical spectra of candidate International Celestial Reference Frame (ICRF)
flat-spectrum radio sources.
Titov O., Stanford L.M., Johnston H.M., Pursimo T., Hunstead R.W.,
Jauncey D.L., Maslennikov K., Boldycheva A.
<Astron. J., 146, 10 (2013)>
=2013AJ....146...10T 2013AJ....146...10T
ADC_Keywords: VLBI ; Galaxies, radio ; QSOs ; BL Lac objects ; Spectroscopy ;
Redshifts
Keywords: BL Lacertae objects: general - galaxies: active -
quasars: emission lines - radio continuum: general - reference systems
Abstract:
Continuing our program of spectroscopic observations of International
Celestial Reference Frame (ICRF) sources, we present redshifts for 120
quasars and radio galaxies. Data were obtained with five telescopes:
the 3.58m European Southern Observatory New Technology Telescope, the
two 8.2m Gemini telescopes, the 2.5m Nordic Optical Telescope (NOT),
and the 6.0m Big Azimuthal Telescope of the Special Astrophysical
Observatory in Russia. The targets were selected from the
International VLBI Service for Geodesy & Astrometry candidate
International Celestial Reference Catalog which forms part of an
observational very long baseline interferometry (VLBI) program to
strengthen the celestial reference frame. We obtained spectra of the
potential optical counterparts of more than 150 compact flat-spectrum
radio sources, and measured redshifts of 120 emission-line objects,
together with 19 BL Lac objects. These identifications add
significantly to the precise radio-optical frame tie to be undertaken
by Gaia, due to be launched in 2013, and to the existing data
available for analyzing source proper motions over the celestial
sphere. We show that the distribution of redshifts for ICRF sources is
consistent with the much larger sample drawn from Faint Images of the
Radio Sky at Twenty cm (FIRST) and Sloan Digital Sky Survey, implying
that the ultra-compact VLBI sources are not distinguished from the
overall radio-loud quasar population. In addition, we obtained NOT
spectra for five radio sources from the FIRST and NRAO VLA Sky Survey
catalogs, selected on the basis of their red colors, which yielded
three quasars with z>4.
Description:
We had a five-night observing run in Visitor Mode at the European
Southern Observatory (ESO) 3.58m New Technology Telescope (NTT) at La
Silla in 2011 December (088.A-0021 (A)) using the ESO Faint Object
Spectrograph and Camera system with grism 13 covering the wavelength
range 3685-9315Å.
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 (GS-2011A-Q-89, GN-2011B-Q-109, GS-2011A-Q-94) using the
Gemini Multi-Object Spectrograph system with grating R400. This
grating covers 4500Å centered either at 5200Å or 6500Å.
Observations with the 2.5m Nordic Optical Telescope (NOT) on La Palma
were carried out using the Andalucia Faint Object Spectrograph and
Camera spectrograph, either with grism5 or grism4 with the WG345
blocking filter. The nominal wavelength ranges for grism4 and grism5
are 3200-9100Å and 5000-10250Å, respectively.
Two objects were observed in Visitor Mode at the 6m Big Azimuthal
Telescope (BTA) telescope of the Special Astrophysical Observatory in
Russia in 2011 August, using the SCORPIO multi-mode focal reducer with
GR300 grism covering the wavelength range 3500-9500Å. Spectral
resolution was typically 20Å.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 103 399 Observed emission lines
table2.dat 45 19 Probable BL Lac objects
table3.dat 45 18 Objects with low signal-to-noise spectra
notes.dat 455 25 Notes
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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)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
J/ApJ/748/49 : Optical spectroscopy of 1LAC broad-line blazars (Shaw+, 2012)
J/AJ/141/182 : Radio and optical properties of QSOs (Kimball+, 2011)
J/A+A/506/1477 : Radio source distribution (Titov+, 2009)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [IVS]
5- 13 A9 --- BName IVS (International VLBI Service for geodesy &
astrometry) source name (BHHMM+DDd)
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 code (BTA, GS, GN, NOT, NTT) (G2)
50- 59 A10 --- Line Emission line identifier
61- 66 F6.1 0.1nm lam.0 Rest wavelength; in Å
68- 73 F6.1 0.1nm lambda [3744/8666] Observed wavelength; in Å
74 A1 --- f_lambda [n] Line not used for redshift determination
76- 81 F6.4 --- Mean redshift
83- 88 F6.4 --- e_ ? Uncertainty in z
89 A1 --- u_ [:] Uncertainty flag in z
91 A1 --- f_ [S] Flag for single-line redshift
92 A1 --- n_BName [*] A note in Section 3.2 for this object
94- 99 F6.4 --- zp ? Previously determined redshift
101-103 A3 --- r_zp Reference for pz (1)
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Note (1): Origin of previously determined redshift as follows:
A09 = Afansasev et al.(2009ARep...53..287A 2009ARep...53..287A);
S12 = Shaw et al. (2012, cat. J/ApJ/748/49);
S = Simbad database (http://simbad.u-strasbg.fr/simbad/);
6dF = 6dF survey (Jones et al., 2009, cat. VII/259).
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Byte-by-byte Description of file: table[23].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [IVS]
5- 13 A9 --- BName IVS (International VLBI Service for geodesy &
astrometry) source name (BHHMM+DDd)
15- 16 I2 h RAh Hour of Right Ascension (J2000)
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 Telescope code (GS, GN, NTT) (G2)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: notes.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- BName IVS source name (BHHMM+DDd)
11-455 A445 --- Note Notes
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Global Notes:
Note (G1): ICRF2 (current International Celestial Reference Frame) radio
position.
Note (G2): Telescope code defined as follows:
BTA = 6m Big Azimuthal Telescope (of the Special Astrophysical Observatory in
Russia);
GS = Gemini South 8.2m telescope;
GN = Gemini North 8.2m telescope;
NOT = 2.5m Nordic Optical Telescope (on La Palma);
NTT = ESO (European Southern Observatory) 3.58m New Technology Telescope at
La Silla.
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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 III. 2017AJ....153..157T 2017AJ....153..157T, Cat. J/AJ/153/157
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 04-Jun-2014