J/A+A/436/457 Ultra-steep spectrum radio sources (Gopal-Krishna+, 2005)
Optical and radio observations of a sample of 52 powerful
ultra-steep spectrum radio sources.
Gopal-Krishna, Ledoux C., Melnick J., Giraud E., Kulkarni V., Altieri B.
<Astron. Astrophys., 436, 457-464 (2005)>
=2005A&A...436..457G 2005A&A...436..457G
ADC_Keywords: Galaxies, radio ; Morphology ; Photometry, UBVRI
Keywords: cosmology: observations - galaxies: active - cooling flows -
galaxies: clusters: general - quasars: general -
radio continuum: galaxies
Abstract:
We present the results of radio (VLA) and optical (ESO/La Silla)
imaging of a sample of 52 radio sources having an ultra-steep radio
spectrum with α mostly steeper than -1.1 at decimetre
wavelengths (median α=-1.22). Radio-optical overlays are
presented to an astrometric accuracy of ∼1". For 41 of the sources,
radio spectral indices are newly determined using unpublished
observations made with the 100-m Effelsberg radio telescope. For 14 of
the sources identified with relatively brighter optical counterparts,
spectroscopic observations were also carried out at La Silla and their
redshifts are found to lie in the range 0.4 to 2.6.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 89 52 Overall properties of the sample galaxies
notes.dat 80 252 Individual notes
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See also:
J/A+AS/93/399 : Optical ID of steep spectrum radio sources (Wieringa+ 1992)
J/A+AS/108/79 : Ultra-steep spectrum radiosources (Roettgering+, 1994)
J/A+AS/143/303 : Ultra steep spectrum radio sources catalog (De Breuck+ 2000)
J/AJ/123/637 : Ultra-steep-spectrum radio sources (De Breuck +, 2002)
J/MNRAS/355/20 : K magnitudes of 74MHz radio sources (Jarvis+, 2004)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name IAU name (HHMM+DDd, B1950)
10- 11 A2 --- n_Name Origin of the object (1)
13- 14 I2 h RAh Right ascension (J2000) (2)
16- 17 I2 min RAm Right ascension (J2000) (2)
19- 23 F5.2 s RAs Right ascension (J2000) (2)
25 A1 --- DE- Declination sign (J2000)
26- 27 I2 deg DEd Declination (J2000) (2)
29- 30 I2 arcmin DEm Declination (J2000) (2)
32- 35 F4.1 arcsec DEs Declination (J2000) (2)
37- 39 A3 --- RMorph Radio morphology (3)
41 A1 --- l_RSize [~<] Limit flag on RSize
42- 44 I3 arcsec RSize ? Radio size
45 A1 --- n_RSize [s] s: see text
47- 51 F5.2 --- alpha Radio spectral index
53- 56 F4.2 Jy RFlux Radio flux at 408MHz (or 327MHz if n_RFlux=")")
57 A1 --- n_RFlux [)] ): indicates RFlux at 327MHz
59 A1 --- Filter [BVRI] Photometric filter
60 A1 --- l_mag [≃>] Limit flag on mag
61- 64 F4.1 mag mag ? Magnitude in "Filter"
66- 68 F3.1 mag e_mag ? rms uncertainty on mag
69 A1 --- n_mag [s] s: see text of the article
71- 74 F4.2 --- z ?=- Redshift
77- 89 A13 --- Obs Details of observations (4)
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Note (1): Radio survey from where the object was selected as follows:
oo = Ooty lunar occultation survey at 327MHz
ml = Molonglo surveys (MC1 and MC2) at 408MHz
mg = MIT (365MHz) - Green-Bank (4.8GHz) survey
gb = Green-Bank (1.4GHz) - Molonglo (408MHz) survey
Note (2): The positions refer to the radio peak for unresolved sources
and to the central radio component if detected. For the remaining
sources, the mid-point between the lobes is adopted.
Note (3): Radio morphology as follows:
D = Double
T = Triple
SR = Slightly Resolved
R = Resolved
U = Unresolved
Note (4): The codes for the optical observations (I,S) are as defined in
Tables 2 and 3 (see "Table 2" and "Table 3" sections below).
Exposure times for imaging ranged between ten and 30min at the ESO
3.6m/NTT 3.5m telescopes, and 20 and 60min at the ESO 2.2m/Danish
1.5m telescopes. Exposure times for spectroscopy are given together
with the comments for each source. The letters "a", "b" and "c"
refer to the quality of the astrometry as follows:
a = astrometric accuracy is ∼1"
b = astrometric accuracy is ∼1.5"
c = astrometric accuracy is ∼2"
Asterisks refer to the sources for which our spectroscopic data did
not yield redshift.
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Table 2: Optical imaging observations
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Run Telescope Instrument Time span CCD Pixel size No. of pixels
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I1 NTT 3.5m EFOSC2 1989 #05 0.2578 512 x 320
I2 ESO 3.6m EFOSC1 1989-1991 #08 0.3375 1024 x 640
I3 ESO 3.6m EFOSC1 1991-1993 #26 0.6094 512 x 512
I4 ESO/MPI 2.2m EFOSC2 1991 #05 0.3500 512 x 320
I5 ESO/MPI 2.2m EFOSC2 1991 #19 0.3340 1024 x 1024
I6 Danish 1.5m DFOSC 1996 Loral 0.3800 2052 x 2052
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Table 3: Optical spectroscopy observations
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Run Telescope Instrument CCD Grism Pixel size Wavelength range
(nm) (nm)
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S1 ESO 3.6m EFOSC1 #08 B300 0.48 350- 700
S2 ESO 3.6m EFOSC1 #08 R300 0.52 500- 900
S3 ESO 3.6m EFOSC1 #08 B1000 1.3 350-1050
S4 ESO 3.6m EFOSC1 #26 B300 0.96 350- 700
S5 ESO 3.6m EFOSC1 #26 R300 1.04 500- 900
S6 NTT 3.5m EMMI #18 #2 0.44 400- 700
S7 ESO/MPI 2.2m EFOSC2 #19 #1 1.0 400- 920
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name IAU name (HHMM+DDd, B1950)
10- 80 A71 --- Note Text of the note
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Nomenclature note:
Objects identified as [GLM2005] JHHMMSS.ss+DDMMSS.s in Simbad
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 29-Sep-2006