J/ApJ/673/78 VLBI suvey around B0218+357 at 90cm (Lenc+, 2008)
A deep, high-resolution survey of the low-frequency radio sky.
Lenc E., Garrett M.A., Wucknitz O., Anderson J.M., Tingay S.J.
<Astrophys. J., 673, 78-95 (2008)>
=2008ApJ...673...78L 2008ApJ...673...78L
ADC_Keywords: Radio sources ; VLBI
Keywords: galaxies: active - quasars: individual (QSO B0218+357, J0226+3421) -
radiation mechanisms: general - techniques: interferometric
Abstract:
We report on the first wide-field, very long baseline interferometry
(VLBI) survey at 90cm. The survey area consists of two overlapping
28deg2 fields centered on the quasar J0226+3421 and the
gravitational lens B0218+357. A total of 618 sources were targeted in
these fields, based on identifications from Westerbork Northern Sky
Survey (WENSS) data. Of these sources, 272 had flux densities that, if
unresolved, would fall above the sensitivity limit of the VLBI
observations. A total of 27 sources were detected as far as 2°
from the phase center. The results of the survey suggest that at least
10% of moderately faint (S∼100mJy) sources found at 90 cm contain
compact components smaller than ∼0.1"-0.3" and stronger than 10% of
their total flux densities.
Description:
A VLBI observation of the gravitational lens B0218+357 was made on 11
November 2005 using all 10 NRAO Very Long Baseline Array (VLBA)
antennas, the Westerbork Synthesis Radio Telescope (WSRT) as a phased
array, and the Jodrell Bank (JB) 76m Lovell Telescope.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 70 103 Astrometry and photometry at 324 MHz for
Field 1 (centered on J0226+3421) targets
table3.dat 70 196 Astrometry and photometry at 324 MHz for
Field 2 (centered on B0218+357) targets
table4.dat 56 28 Source and image characteristics and
astrometric errors
--------------------------------------------------------------------------------
See also:
VIII/62 : The Westerbork Northern Sky Survey (WENSS) (Leiden, 1998)
Byte-by-byte Description of file: table[23].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 F4.2 deg Ann1 Annulus from field center (lower bound)
5 A1 --- --- [-]
6- 9 F4.2 deg Ann2 Annulus from field center (upper bound)
11- 22 A12 --- WENSS WENSS source designation, BHHMM.m+DDMMA
23 A1 --- m_WENSS [AB] Multiplicity index on WENSS
25 A1 --- n_WENSS [WV] W=WENSS target source, V=VLBI detection
27- 28 I2 h RAh Right ascension (J2000.0)
30- 31 I2 min RAm Right ascension (J2000.0)
33- 39 F7.4 s RAs Right ascension (J2000.0)
41 A1 --- DE- Declination sign (J2000.0)
42- 43 I2 deg DEd Declination (J2000.0)
45- 46 I2 arcmin DEm Declination (J2000.0)
48- 53 F6.3 arcsec DEs Declination (J2000.0)
55- 58 I4 mJy Speak Peak flux density per solid beam angle at 90cm
(in mJy/beam)
61- 64 I4 mJy Sint Integrated flux at 90cm
66- 70 F5.2 --- SI ? Spectral index alpha estimated from the
WENSS and NVSS integrated flux densities
where available
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- WENSS WENSS designation (excepted 3C 84)
13 A1 --- m_WENSS Multiplicity index on Source
15 I1 --- Fld [1/2]? Field number
17- 20 F4.2 deg Dpc ? Distance of the source from the phase
center of the observed field
22- 24 I3 mas Beam1 Beam size
25 A1 --- --- [x]
26- 28 I3 mas Beam2 Beam size
30- 32 I3 deg PA [-90/90] Beam position angle
34- 36 F3.1 mJy noise 1σ residual noise after the source model
has been subtracted from the image (mJy/beam)
38- 40 A3 --- Ref Reference for positions (1)
42- 47 F6.3 arcsec DE Measured offset of the VLBI source peak from
the position listed in reference
49- 51 I3 deg thetaE Position angle of the VLBI source peak in
relation to the position listed in reference
53- 56 F4.1 --- ds Measured offset of the VLBI source peak in
relation to the position listed in reference
in terms of the 1σ astrometric
precision σp
--------------------------------------------------------------------------------
Note (1): References as follows:
B02 = 2.3/8.3GHz VLBA, Beasley et al., 2002, Cat. J/ApJS/141/13
C98 = 1.4GHz VLA, Condon et al., 1998, Cat. VIII/65
D96 = 365MHz Texas interferometer, Douglas et al., 1996, Cat. VIII/42
P92 = 8.4GHz VLA, Patnaik et al., 1992, Cat. VIII/60
R94 = 1.4GHz VLA, Rottgering et al., 1994, Cat. J/A+AS/108/79
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 07-Apr-2010