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Continued X-ray Brightening of V0332+53

ATel #371; Ron Remillard (for ASM team at MIT and GSFC)
on 22 Dec 2004; 15:21 UT
Credential Certification: Ron Remillard (rr@space.mit.edu)

Subjects: X-ray, Transient, Pulsar

Referred to by ATel #: 372, 381, 382, 388

The XTE All-Sky monitor shows continued brightening of V0332+53, with an average flux of 1.1 Crab (2-12 keV) during the first half of 2004 Dec. 22. The true flux is certain to be substantially higher since the source is extremely hard, even for X-ray pulsars. The ASM count rate is evaluated here using cameras 2 and 3 only, since detector gain differences for camera 1 skew the results, given that normalizations are tied to the spectrum of the Crab Nebula. V0332+53 is the brightest X-ray pulsar observed with the ASM since the outburst maximum of the 'bursting pulsar' (GRO J1744-28), which was observed at 1.3 Crab on 1996 January 12. The average hardness ratio (5-12 keV / 3-5 keV) for V0332+53 over the last 18 days is HR2 = 3.40, which exceeds other pulsars, e.g. GRO J1744-28 (2.4), Vela X-1 (2.4), Cen X-3 (2.1), and 4U0115+63 (3.0).