GCN Circular 37483

M. A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), T. Sbarrato
(INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), J.A.
Kennea (PSU) and P.A. Evans (U. Leicester) reports on behalf of the
Swift-XRT team:

Swift-XRT has performed follow-up observations of the
SVOM/ECLAIRs-detected burst GRB 240911A in a series of observations
tiled on the sky. The total exposure time is 2.9 ks, distributed over 3
tiles; the maximum exposure at a single sky location was 1.6 ks. The
data were collected between T0+73.0 ks and T0+79.5 ks, and are entirely
in Photon Counting (PC) mode. 

Two uncatalogued X-ray sources have been detected, however none of them
is above the RASS limit or shows definitive signs of fading. Therefore,
at the present time we cannot identify which, if any, is the afterglow.
Details of these sources are given below:

Source 1:
  RA (J2000.0):  351.4579  =  23:25:49.91
  Dec (J2000.0): +21.3760  =  +21:22:33.6
  Error: 13.5 arcsec (radius, 90% conf.)
  Count-rate: (3.7 [+2.3, -1.6])e-3 ct s^-1   
  Distance: 554 arcsec from SVOM/ECLAIRs position.

Source 2:
  RA (J2000.0):  351.5268  =  23:26:6.43
  Dec (J2000.0): +21.2944  =  +21:17:39.8
  Error: 8.2 arcsec (radius, 90% conf.)
  Count-rate: (5.5 [+3.6, -2.6])e-3 ct s^-1   
  Distance: 771 arcsec from SVOM/ECLAIRs position.

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00128.

This circular is an official product of the Swift-XRT team.