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Renewed Low Level X-ray Activity of GX 339-4

ATEL # 944; J. H. Swank (GSFC), E. A. Smith (RSIS/GSFC), D. M. Smith (U. C. Santa Cruz), C. B. Markwardt (UMD/GSFC)
on 14 Nov 2006; 18:11 UT
Distributed as an Instant Email Notice (Transients)
Password Certification: Jean Swank (

Subjects: Radio, X-ray, Request for Observations, Black Holes, Transients

Observations with the Rossi X-ray Timing Explorer (RXTE) show that the suspected black-hole binary GX 339-4 has again become active. It was last seen to be X-ray active on 2006 June 14, in decay from a small outburst. At 17:48 UTC on 12 Nov 2006, the Proportional Counter Array (PCA) found, in a 1.3 ks monitoring observation, that the flux was 4 mCrab and variable. In an additional 1.4 ks observation at 1:14 UT on 14 Nov the Proportional Counter Array (PCA) found the flux was an average of 6, 8, and 10 mCrab in the energy ranges 2-10, 10-20, and 20-40 keV, respectively. The spectrum was well fit with a power law with photon index of 1.67, assuming a hydrogen column density of 6x10^21 cm^-2, as has been seen before. The flux exhibited high variability, with peaks of 40 mCrab in oscillations on time scales of about 3 minutes.

Multiwavelength observations, especially radio would be valuable, although the source is already within 38 degrees of the sun. Additional RXTE observations are scheduled through 25 Nov, when it is 30 degrees from the sun.

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R. E. Rutledge , Editor
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