On-going radio observations of GRO J1655-40
ATel #609; M. P. Rupen (NRAO/GSFC), V. Dhawan, A. J. Mioduszewski (NRAO)
on 18 Sep 2005; 16:26 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Michael P. Rupen (mrupen@nrao.edu)
Subjects: Radio, Infra-Red, Optical, Request for Observations, Binary, Black Hole, Transient
We have been observing the black hole X-ray binary and microquasar
GRO J1655-40 on a regular basis since the beginning of the current outburst
(February 2005; ATel #414, 415, etc.). Following the report that the source
was returning to the hard state (ATel #607), we made short observations
on Sep. 17 UT, resulting in the following non-detections:
Sep. 17.03, 8.46 GHz: 0.07 +/- 0.08 mJy/beam; Sep. 17.97, 4.86 and 8.46 GHz:
-0.11 +/- 0.17 and -0.11 +/- 0.14 mJy/beam, respectively. In each case the
quoted numbers are the flux density at the nominal position of the source,
+/- the rms noise level measured in a nearby, empty region. GRO J1655-40
is clearly much weaker at radio wavelengths than during the initial hard
phase at the beginning of the current outburst. The full radio light curve
is shown at
http:/
/www.aoc.nrao.edu/~mrupen/XRT/GRJ1655-40/grj1655-40.shtml
Further VLA observations are planned for the following dates:
- 20sep05 2139-2241 UT
- 21sep05 2337-22sep05 0031 UT
- 22sep05 2131-2326 UT
- 26sep05 2117-2217 UT
Should detections result, we may try for further observations before
the end of the month.
Simultaneous observations at other bands would
be very valuable.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc.
Radio observations of GRO J1655-40
