GCN Circular 40423
Subject
GRB 250510A: Swift-XRT observations
Date
2025-05-10T16:54:51Z (3 days ago)
From
Simone Dichiara at Pennsylvania State University <sbd5667@psu.edu>
Via
Web form
S. Dichiara (PSU), K.L. Page (U. Leicester), J.A. Kennea (PSU),
P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi
(INAF-IASFPA) , M. A. Williams (PSU), J.P. Osborne (U. Leicester),
A.P. Beardmore (U. Leicester) 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 250510A, from 10.2 ks to
20.8 ks after the SVOM/ECLAIRs trigger. The data are entirely in
Photon Counting (PC) mode.
Within the SVOM/ECLAIRs 90% C.L. error region (GCN #40415) we detect
the EP-FXT source EPF_J185624.8+181937 (GCN#40420) at RA, Dec =
284.10364, +18.3267 which is equivalent to:
RA (J2000): 18h 56m 24.87s
Dec (J2000): +18d 19′ 36.0″
with an uncertainty of 5.7 arcsec (radius, 90% confidence).
The source has a mean count rate of 7.3e-03 ct/sec and a flux of 3.2
(+1.3, -1.1) × 10^-13 erg cm^-2 s^-1 (0.3-10 keV); we note that this
position is also consistent with a known 2MASS source,
2MASS J18562485+1819380.
No other X-ray sources have been detected. The 3-sigma upper limit in
the field ranges from ~4.4e-03 to ~1.0e-02 ct s^-1, corresponding to a
0.3-10 keV observed flux of 1.9e-13 to 4.4e-13 erg cm^-2 s^-1 (assuming
a typical GRB spectrum).
The results of the XRT-team automatic analysis are available at
https://www.swift.ac.uk/SVOM/SVOM_FIELD00016/.
This circular is an official product of the Swift-XRT team.