J/A+A/601/A35 High-fidelity VLA imaging of 3C273 (Perley+, 2017)
High-fidelity VLA imaging of the radio structure of 3C 273.
Perley R.A., Meisenheimer K.
<Astron. Astrophys. 601, A35 (2017)>
=2017A&A...601A..35P 2017A&A...601A..35P (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Radio sources
Keywords: radio continuum: galaxies - galaxies: jets - quasars: general
Abstract:
3C 273, the nearest bright quasar, comprises a strong nuclear core and
a bright, one-sided jet extending ∼23 arcseconds to the SW. The source
has been the subject of imaging campaigns in all wavebands. Extensive
observations of this source have been made with the Very Large Array
and other telescopes as part of a campaign to understand the jet
emission mechanisms. Partial results from the VLA radio campaign have
been published, but to date, the complete set of VLA imaging results
has not been made available.
We have utilized the VLA to determine the radio structure of 3C273 in
Stokes I, Q, and U, over the widest possible frequency and resolution
range.
The VLA observed the source in all four of its configurations, and
with all eight of its frequency bands, spanning 73.8MHz to 43GHz.
The data were taken in a pseudo-spectral line mode to minimize the
VLA's correlator errors, and were fully calibrated with subsequent
self-calibration techniques to maximise image fidelity.
Images in Stokes parameters I, Q, and U, spanning a resolution range
from 6 arcseconds to 88 milliarcseconds are presented. Spectral index
images, showing the evolution of the jet component are shown.
Polarimetry demonstrates the direction of the magnetic fields
responsible for the emission, and rotation measure maps show the RM to
be very small with no discernible trend along or across the jet. This
paper presents a small subset of these images to demonstrate the major
characteristics of the source emission. A library of all ∼500 images
has been made available for open, free access by interested parties.
Description:
The results presented here are from three separate observational
campaigns utilizing the Very Large Array, each with different goals.
The first, taken in 1987, 1991 and 1999 under project codes AP134,
AB608, and AB916 was intended to search for changes in the structure
of the radio jet over the 14-year span of time. The second, in 1995
through 1997, under project codes AR334 and AR371, were part of a full
coverage study of the jet emission properties. Neither of these
projects included observations from the low frequency bands, at 73.8
and 327MHz. The results included in this paper from these bands are
taken from project AK461, whose goal was to demonstrate the imaging
capability of the VLA at low frequencies by observing a selection of
3C sources, including 3C273.
Objects:
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RA (2000) DE Designation(s)
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12 29 06.70 +02 03 08.7 3C 273 = QSO J1229+0203
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 34 10 VLA observing log
list.dat 150 294 List of fits images
fits/* . 294 Individual fits images
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See also:
ftp://ftp.aoc.nrao.edu/pub/staff/rperley/3C273/ : All images
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Project Project name
7- 17 A11 "date" Date Observation date
19 A1 --- Conf [ABCD] Configuration
21- 31 A11 --- Bands Observed bands (1)
33- 34 I2 h Dur Duration
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Note (1): Bands as follows:
4 = 73.8 MHz
P = 327 MHz
L = 1365 MHz
C = 4885 MHz
X = 8415 MHz
U = 14965 MHz
K = 22485 MHz
Q = 43315 MHz
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 37 A10 "date" Obs.date Observation date
39- 46 F8.5 GHz Freq Observed frequency
48- 51 I4 Kibyte size Size of FITS file
53- 72 A20 --- FileName Name of FITS file, in subdirectory fits (1)
74-150 A77 --- Title Title of the FITS file
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Note (1): In general, files are named thusly: bb273-rr-type where
bb are the band(s) utilized for the image
rr is the resolution of the restoring beam, in arcseconds.
type is the type of image.
There are many possibilities for "type". These include:
- A leading I, Q or U denotes the polarization
- SPX denotes spectral index
- DGP denotes degree of polarization.
- POLA and PANG denote polarization angle
- POLC denote polarization fraction, corrected for Ricean bias
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Acknowledgements:
Rick Perley, rperley(at)aoc.nrao.edu
(End) Patricia Vannier [CDS] 10-Jan-2017