Renewed X-ray activity in GX 339-4
ATel #231; D. M. Smith (U. C. Santa Cruz), W. A. Heindl (U. C. San Diego), J. H. Swank (NASA/GSFC), J. Wilms (IAA Tuebingen), K. Pottschmidt (ISDC)
on 10 Feb 2004; 07:25 UT
Distributed as an Instant Email Notice Transients
Credential Certification: David M. Smith (dsmith@ssl.berkeley.edu)
Subjects: X-ray, Request for Observations, Binary, Black Hole, Transient
Recent monitoring of GX 339-4 in the 2-30 keV X-ray band by the Proportional Counter Array
(PCA) of the Rossi X-ray Timing Explorer (RXTE) shows that the newly reported activity in the
optical and radio (ATEL #230) is accompanied by faint X-ray emission.
On February 1 at 04:00 UT, the X-ray count rate was 1 count/second/Proportional Counter Unit (PCU).
On February 9 at 05:40 UT, the rate was about 6 times higher, yielding sufficient statistics
for a spectral fit, which shows the source to be in the hard state (photon power law index 1.55).
For comparison, the highest count rate seen in the hard state for GX 339-4 in its last outburst
(ATEL #85) was about 900 counts/second/PCU.
The next RXTE monitoring observations in this series are on February 13 and February 16.
Other observations are encouraged.