Complex evolution of radio spectrum in GRO J1655-40
ATel #437; M. P. Rupen (NRAO/GSFC), V. Dhawan, A. J. Mioduszewski (NRAO)
on 7 Mar 2005; 19:33 UT
Credential Certification: Michael P. Rupen (mrupen@nrao.edu)
Subjects: Radio, Binary, Black Hole, Transient
Referred to by ATel #: 487
The radio spectrum of the black hole X-ray binary GRO J1655-40 has undergone
rapid changes over the past few days, according to observations by the
Very Large Array (VLA). On Mar. 4th, data taken between 12:09 and 12:41 UT
give flux densities of
1.2 +/- 0.2, 1.9 +/- 0.1, and 1.5 +/- 0.1 mJy
at 1.425, 4.860, and 8.460 GHz, respectively;
on Mar. 6th, observations between 12:16 and 12:56 UT yield values of
1.8 +/- 0.2, 1.3 +/- 0.1, and 1.2 +/- 0.1 mJy
at the same frequencies. Combined with previous observations (ATEL #419,
ATEL #425, ATEL #434) these data suggest a small radio flare sometime between
Feb. 27th and Mar. 4th (i.e., during or just after the X-ray plateau,
ATEL #432, ATEL #433), followed by a return to the earlier fairly flat spectrum.
The radio light curve is posted at:
http://www.aoc.nrao.edu/~mrupen/XRT/GRJ1655-40/grj1655-40.shtml
Further radio observations are planned.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc.
Radio light curve of GRO J1655-40
