TITLE: GCN CIRCULAR NUMBER: 38182 SUBJECT: GRB 241112B: Swift-XRT afterglow detection DATE: 24/11/12 19:15:04 GMT FROM: Phil Evans at U of Leicester pae9@star.le.ac.uk
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.
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