J/A+A/555/A134 Variability monitoring of QSO B1156+295 at 4.8GHz (Liu+, 2013)
Two-year monitoring of intra-day variability of quasar 1156+295 at 4.8 GHz.
Liu B.-R., Liu X., Marchili N., Liu J., Mi L.-G., Krichbaum T.P.,
Fuhrmann L., Zensus J.A.
<Astron. Astrophys. 555, A134 (2013)>
=2013A&A...555A.134L 2013A&A...555A.134L
ADC_Keywords: QSOs ; Radio continuum
Keywords: quasars: individual: 4C +29.45 - radio continuum: galaxies -
galaxies: jets - ISM: structure - scattering
Abstract:
The quasar 1156+295 (4C +29.45) is one of the targets in the Urumqi
monitoring program which aimed to search for evidence of annual
modulation in the timescales of Intra-Day Variable (IDV) sources.
The IDV observations of 1156+295 were carried out nearly monthly from
October 2007 to October 2009, with the Urumqi 25m radio telescope at
4.8GHz.
The source has shown prominent IDV of total flux density in most
observing sessions with variability timescales of 1 day at 4.8GHz.
The estimated IDV timescales seem to follow an annual cycle, which can
be fitted with an anisotropic interstellar scintillation (ISS) model,
suggesting that a significant part of the flux density variations is
due to ISS. The source underwent a dramatic flare in 2008. We studied
the possible consequences of the flare on the IDV of 1156+295, by
comparing the changes in its variability characteristics with the
evolution of the 43 GHz VLBA core size of the source.
The quasar 1156+295 shows evidence for an annual modulation of its IDV
timescales at 4.8GHz, the ISS-induced IDV timescales and variability
strength might be affected by the overall activity state of the source
core. More frequent IDV and VLBI measurements are required to confirm
the relation between the IDV appearance and the core-size evolution of
the source.
Description:
The Urumqi Intra-Day Variable (IDV) observation campaign was carried
out from August 2005 to January 2010 with the Urumqi 25m radio
telescope, at a frequency of 4.8GHz. Observing sessions of 3 to 5 days
were typically scheduled once per month. The observing strategy and
the detailed calibration method were described in Marchili et al.
(2010A&A...509A..47M 2010A&A...509A..47M). The quasar 1156+295 (4C +29.45) was included in
our monitoring program in late 2007, observed in 18 observing sessions
from October 2007 to October 2009.
Objects:
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RA (2000) DE Designation(s)
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11 59 31.83 +29 14 43.8 4C +29.45 = QSO B1156+295
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 38 776 All flux density obtained with the Urumqi 25m
radio telescope at 4.8GHz
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See also:
J/A+A/544/A34 : Bright AGN VLBI imaging study at 2 and 8GHz (Pushkarev+, 2012)
J/AJ/142/108 : Radio variability of compact, flat-spectrum AGNs (Koay+, 2011)
J/ApJ/737/45 : Variable 1.4GHz radio sources from NVSS & FIRST (Ofek+, 2011)
J/MNRAS/418/2260 : VLBI observations of NRAO 530 at 22, 43 & 86GHz (Lu+, 2011)
J/ApJS/175/314 : VSOP 5GHz AGN survey V. (Dodson+, 2008)
J/AJ/135/1384 : R-band variability in 5 blazars (Gupta+, 2008)
J/ApJ/616/110 : VSOP 5GHz AGN Survey. IV (Horiuchi+, 2004)
J/ApJS/131/95 : VSOP 5 GHz continuum survey (Fomalont+, 2000)
J/PASJ/52/997 : VSOP 5 GHz AGN Survey (Hirabayashi+, 2000)
J/A+AS/139/545 : 1-22 GHz spectra survey (Kovalev+, 1999)
J/A+AS/128/315 : BVRI photometry of blazars (Jia Guibin+ 1998)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 14 F14.8 d MJD Modified Julian Date of observation
18- 24 F7.5 Jy Flux Calibrated flux density at 4.8GHz
28- 38 E11.6 Jy e_Flux Flux uncertainty
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Acknowledgements:
Xiang Liu, <liux(at)xao.ac.cn>
(End) Xiang Liu [XAO], Emmanuelle Perret [CDS] 04-Jun-2013