NRAO VLA service monitoring observations of Sgr A*
ATel #5153; Claire J. Chandler(NRAO) and Lorant O. Sjouwerman(NRAO)
on 21 Jun 2013; 16:03 UT
Credential Certification: Lorant Sjouwerman (lsjouwer@nrao.edu)
Subjects: Radio, AGN, Black Hole, Transient
Referred to by ATel #: 5159
As part of an ongoing community service observing program to follow the
expected encounter of the G2 cloud with the black hole Sgr A* in 2013
(https://science.nrao.edu/enews/5.10/index.shtml#g2_encounter), the
NRAO Very Large Array observed the Sgr A region starting 2013 June 9
05:45 UT for two hours, cycling through the standard observing bands
at their default 8-bit (i.e., up to 2 GHz bandwidth) continuum
frequencies. The data from the monitoring program are publicly
available through the NRAO data archive immediately after observing
has completed, and the flux densities are published by NRAO staff as
soon as the data are reduced. The June 9 data were reduced with a
modified VLA CASA pipeline, and the flux density of Sgr A* was
measured as listed below. Due to the compact configuration of the VLA
(i.e., C-configuration), and Sgr A* being embedded in the extended
emission of the circumnuclear disk and the supernova shell, the lower
frequency measurements are upper limits. The cumulative results of
the monitoring effort are posted on the service observing web page
https://science.nrao.edu/science/service-observing and so far do not
indicate a significant brightening of the emission from the direction
of Sgr A* over the period 2012 October to 2013 June, within the
calibration uncertainties.
Measurements of 2013 June 9:
1.5 GHz (14.95 Jy upper limit)
3.0 GHz (1.79 Jy upper limit)
5.5 GHz (1.21 Jy upper limit)
10.0 GHz 0.96 +/-10% Jy
14.0 GHz 1.09 +/-10% Jy
21.2 GHz 1.00 +/-10% Jy
32.0 GHz 1.28 +/-10% Jy
41.0 GHz 1.29 +/-10% Jy
