RXTE Discovers Faint Transient XTE J1637-498
ATel #1699; C. B. Markwardt (CRESST/U. Md./NASA/GSFC), D. Pereira (WYLE/NASA/GSFC), J. H. Swank (NASA/GSFC)
on 5 Sep 2008; 20:42 UT
Credential Certification: Craig B. Markwardt (craigm@lheamail.gsfc.nasa.gov)
Subjects: X-ray, Request for Observations, Binary, Black Hole, Neutron Star, Transient
During regular scans of the galactic bulge and ridge regions on
2008-08-29, RXTE PCA discovered a new source. A dedicated follow-up
scan on 2008-08-30 produced a best-fit position of RA, Dec = 249.35,
-49.80 (J2000), with a 95% error radius of 6 arcmin. Note that
because of galactic ridge emission, and significant source
variability, the true uncertainties may have a non-statistical
component. We designate this source XTE J1637-498.
In retrospect, the source was detected in PCA bulge scans on Aug
25.5, 29.3, Sep 1.4 and 5.1 with 2-10 keV fluxes of 2.5, 3.9, 2.6 and
1.8 mCrab, respectively, with typical uncertainties of about 0.6
mCrab. Thus, the source may have peaked already. Before the detection,
the typical 95% upper limit is about 1 mCrab.
Examining the small amounts of timing data available during scans, no
obvious timing signatures were present, such as pulsations, bursts or
high frequency QPOs, although there may be a ~0.2 Hz QPO. Little
pointed data is available for spectral analysis. Thus, at this time,
the nature of the source is still uncertain.
