TITLE: GCN CIRCULAR NUMBER: 40389 SUBJECT: GRB 250507A: Swift-XRT refined Analysis DATE: 25/05/07 22:02:18 GMT FROM: Phil Evans at U of Leicester pae9@star.le.ac.uk
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. A. Williams (PSU), S. Dichiara (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
We have analysed 1.8 ks of XRT data for GRB 250507A, from 7.4 ks to 12.5 ks after the SVOM/ECLAIRs trigger. The data are entirely in Photon Counting (PC) mode. We detect an uncatalogued X-ray source within the SVOM/ECLAIRs 90% C.L. error region (GCN #40374) at RA, Dec = 183.06416, -23.5888 which is equivalent to:
RA (J2000): 12h 12m 15.40s Dec (J2000): -23d 35' 19.6"
with an uncertainty of 4.2 arcsec (radius, 90% confidence). This position is 15.6 arcsec from the SVOM/MXT position (GCN #40381) and 2.5 arcsec from the source detected by EP-FXT (GCN #40385).
The source has a mean count rate of 2.6e-02 ct/sec and a flux of 1.11 (+0.21, -0.20) × 10^-12 erg cm^-2 s^-1 (0.3-10 keV); we cannot determine at the present time whether it is fading. However, the decrease in flux compared to the SVOM/MXT observation suggests this source is the afterglow.
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00019769.
This circular is an official product of the Swift-XRT team.
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