NRAO VLA service monitoring observations of Sgr A*
ATel #5036; Claire J. Chandler(NRAO) and Lorant O. Sjouwerman(NRAO)
on 1 May 2013; 17:49 UT
Credential Certification: Lorant Sjouwerman (lsjouwer@nrao.edu)
Subjects: Radio, AGN, Black Hole, Transient
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 April 26 10:15 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 April 26 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., D-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 April, within the calibration
uncertainties.
Measurements of 2013 April 26:
1.5 GHz (17.32 Jy upper limit)
3.0 GHz (7.80 Jy upper limit)
5.5 GHz (2.37 Jy upper limit)
10.0 GHz (2.65 Jy upper limit)
14.0 GHz (1.59 Jy upper limit)
21.2 GHz 1.20 +/-10% Jy
32.0 GHz 1.55 +/-10% Jy
41.0 GHz 1.79 +/-10% Jy
