TITLE:   GCN CIRCULAR
NUMBER:  40037
SUBJECT: GRB 250403A: Swift-XRT observations
DATE:    25/04/04 03:32:07 GMT
FROM:    Simone Dichiara at Pennsylvania State University <sbd5667@psu.edu>

S. Dichiara (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB), K.L. 
Page and P.A. Evans (U.Leicester) reports on behalf of the Swift-XRT team:

We have analysed  401 s of XRT data for the GRB 250403A detected by 
Fermi GBM (Fermi team, GCN circ. 40025) and SVOM/ECLAIRs (SVOM trigger 
sb25040305; Julakanti et al., GCN circ. 40026), from T0+7.62 ks to T0+8.02 
ks after the SVOM/ECLAIRs trigger. The data are entirely in Photon Counting 
(PC) mode.

We find an uncatalogued X-ray source 3.1 sigma above the RASS limit, 
consistent with the reported optical counterpart (Starling et al., 
GCN 40028, Chao et al., GCN 40029, Guowang et al., GCN 40031, Li et al., GCN 
40032). Details of this source are given below:

Source 1:
  RA (J2000.0):   194.6162  =  12:58:27.90
  Dec (J2000.0): -24.3800  =  -24:22:47.9
  Error: 3.7 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.29 (±0.07) ct s-1   
  Flux: 1.2 (±0.3) ×10-11 erg cm-2 s-1 (observed, 0.3-10 keV)

This XRT position is 2.5 arcsec away from the optical position (Starling et 
al., GCN 40028).
The results of the XRT-team automatic analysis of the XRT observations, 
including a position-specific upper limit calculator, are available at 
https://www.swift.ac.uk/SVOM/SVOM_FIELD00010/.

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