GCN Circular 38182

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore
(U. Leicester), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), M.
Ferro (INAF-OAB), 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:

Swift-XRT has performed follow-up observations of the
SVOM/ECLAIRs-detected burst GRB 241112B, collecting 2.5 ks of Photon
Counting (PC) mode data between T0+11.0 ks and T0+17.6 ks. 

Two uncatalogued X-ray sources are detected consistent with being
within 414 arcsec of the SVOM/ECLAIRs position, of which one ("Source
1") is above the LSXPS 3-sigma upper limit at this position, and is
therefore likely the GRB afterglow.  The position of this source is RA,
Dec=29.0386, +9.1080 which is equivalent to:

RA (J2000): 01:56:9.26
Dec(J2000): +09:06:29.0

with an uncertainty of 4.1 arcsec (radius, 90% confidence).  This
position is 2.5 arcmin from the SVOM/ECLAIRs position.	The source has
a mean count rate of 2.1e-02 ct/sec; we cannot determine at the present
time whether it is fading.

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.9 (+0.9, -0.5). The
best-fitting absorption column is  9 (+30, -3) x 10^20 cm^-2,
consistent with the Galactic value of 5.6 x 10^20 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 3.6 x 10^-11 (4.3 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     9 (+30, -3) x 10^20 cm^-2
Galactic foreground: 5.6 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.9 (+0.9, -0.5)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021730.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021730.

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