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GCN Circular 41086

Subject
GRB 250713A: Swift-XRT observations
Event
GRB 250713A
Date
2025-07-14T05:58:35Z (a day ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi  (INAF-IASFPA) , A.P.
Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N.
Burrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-OAR), A. D'Ai (INAF-IASFPA),
P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), M. Ferro
(INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato
(INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the
Swift-XRT team:

Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected source
GRB 250713A, collecting 2.0 ks of Photon Counting (PC) mode data between T0+429 s
and T0+6.4 ks after the trigger. We have detected 1 source. This has been
automatically classified as an uncatalogued X-ray source.

Uncatalogued X-ray sources
--------------------------

  Source 1 (SWIFT J222820.3+385214):
  ==================================
    RA (J2000.0):  337.0847  =	22h 28m 20.33s
    Dec (J2000.0): +38.8706  =	+38d 52' 14.2"
    Error:	   7.0 (arcsec, radius, 90% confidence).
    Detect flag:   GOOD
    Distance:	   8.2 arcmin from the SVOM/ECLAIRs position.
    Mean rate:	   (7.7 [+2.8, -2.3])e-3 ct s^-1
    Mean flux:	   (2.94 [+1.07, -0.88])e-13 erg cm^-2 s^-1
    Peak rate:	   (7.7 [+2.8, -2.3])e-3 ct s^-1
    Peak flux:	   (2.94 [+1.07, -0.88])e-13 erg cm^-2 s^-1
    ECF:	   3.84e-11 erg cm^-2 ct^-1, assuming NH=1.27e+21 cm^-2,
		   gamma=1.63; determined from a spectral fit.
    XMM UL:	   2.2e-12 erg cm^-2 s^-1, (0.3-10 keV)
	 so the source is 19.2-sigma above this 3-sigma upper limit.
    There is no evidence for fading.

This source is not spatially consistent with any of those detected by EP-FXT (Circ.
41085).

All fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with
catalogues and upper limits  from other missions, we assumed a power-law spectrum
with NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated.

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.

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