GRO J1008-57 Brightening
ATel #413; Jean Swank (GSFC) for the RXTE team
on 19 Feb 2005; 00:06 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Jean Swank (swank@milkyway.gsfc.nasa.gov)
Subjects: X-ray, Binary, Transient, Pulsar
The transient pulsar GRO J1008-57 may be starting an outburst.
On Feb 18.00, the ASM on the Rossi X-Ray timing Explorer (RXTE)
detected a flux of 36(3) mCrab. The source first spent a week, starting
on Feb 6, at a level of 5 mcrab; it then rose to 20 mcrab on Feb 15. The
ASM hardness ratio HR2 is 2.0(0.3), consistent with a pulsar spectrum,
in comparison to the Crab at 1, though soft compared to the still
active V0332+53. The Gamma-Ray Observatory discovered 93.5 s
pulsations in the discovery outburst of July 1993, which reached a
peak of 1.4 Crab (Bildsten et al. 1997, ApJS. 113, 367; Shrader et
al. 1999, ApJ, 512,920). A probable Be star companion was found at
that time (Coe et al. 1994, MNRAS, 270, L57).
