Discovery of XTE J1747-274
ATel #498; C. B. Markwardt (U. Maryland & NASA/GSFC), J. H. Swank (NASA/GSFC)
on 23 May 2005; 16:25 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Craig B. Markwardt (craigm@lheamail.gsfc.nasa.gov)
Subjects: X-ray, Request for Observations, Binary, Black Hole, Neutron Star, Transient
A new source has appeared in scans of the galactic center by the RXTE
Proportional Counter Array (PCA). The flux increase first became
noticeable in PCA scans on May 11, 15 and 18. Unfortunately, because
this region of the sky is relatively crowded, the flux increase was
attributed to the nearby source GCRT J1746-2757.
On May 20, 14h UT, the flux had become bright enough to be distinct
from other nearby sources. We fitted for the position in the bulge
scan data, and found R.A. = 17h47m38s, Decl. = -27o26m (J2000), and
thus designate the source XTE J1747-274.
Because there are a number of bright sources nearby, the position
error is dominated by systematic uncertainties. Based on two trial
fits, we estimate the error to be < 8 arcmin. There are no catalogged
galactic X-ray sources within 15 arcmin of this position.
After re-processing the PCA scan data of the past few months with the
new source included, no flux increase in GCRT J1746-2757 is needed.
The fluxes of XTE J1747-274 on May 11.4, 15.6, 18.3 and 20.6 were 12
+/- 3, 17 +/- 4, 10 +/- 2 and 48 +/- 4 mCrab (2-10 keV), respectively.
Thus the source appears to be brightening irregularly.
No pulsations or QPOs are detectable in the brief (10-20 second)
PCA scan passes over the source.
