Renewed Radio Emission from GRO J1655-40

ATel #612; Catherine Brocksopp (MSSL), Stephane Corbel (Univ. Paris & CEA Saclay), Michael Rupen (NRAO/GSFC),Bob Sault, Tasso Tzioumis (ATNF), Vivek Dhawan, Amy Mioduszewski (NRAO), Giuseppe Cimo (UTAS), Rob Fender (Southampton)
on 25 Sep 2005; 09:33 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Catherine Brocksopp (cb4@mssl.ucl.ac.uk)

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Following the return of the X-ray source of GRO J1655-40 to the low/hard state (ATel #607), we have continued to monitor the expected radio source with the Australia Telescope Compact Array (ATCA) and Very Large Array (VLA).

Weak radio emission was detected on 21 Sept 2005, for the first time since May 2005. The flux was continuing to rise on 22 Sept.

The data recorded are as follows:

20 Sept, MJD 53633.916 (VLA) <0.62 mJy (4860 MHz)
21 Sept, MJD 53634 (ATCA) 0.31+/-0.08 mJy (4800 MHz) 0.36+/-0.08 mJy (8640 MHz)
22 Sept, MJD 53635.931 (VLA) 0.66+/-0.09 mJy (4860 MHz)


The ATCA data show a flat spectrum, consistent with the compact jet that is typically associated with the low/hard state.

Additional radio monitoring is planned and we encourage further IR/optical observations. The full radio lightcurve can be seen at http://www.aoc.nrao.edu/~mrupen/XRT/GRJ1655-40/grj1655-40.shtml