TITLE:   GCN CIRCULAR
NUMBER:  45548
SUBJECT: GRB 260903A: Swift-XRT observations
DATE:    26/09/10 14:57:05 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

S. Lanava (PSU), J.P. Osborne (U. Leicester), E. Ambrosi  (INAF-IASFPA)
, M. Capalbi (INAF-OAR), M. Perri (SSDC & INAF-OAR), S. Dichiara (PSU),
J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U.
Leicester) 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 260903A, collecting  3.9 ks of Photon
Counting (PC) mode data between T0+498.4 ks and T0+554.5 ks. 

No X-ray sources have been detected at the position of the optical
afterglow (Li et al. GCN 45504, Saccardi et al. GCN 45505, Malesani et
al. GCN 45508, Russeil et al. GCN 45509, Li et al. GCN 45510, Bochenek
et al. GCN 45516). The 3-sigma upper limit in the field is 0.002 ct 
s^-1, corresponding to a 0.3-10 keV observed flux of 8.1e-14 erg cm^-2
s^-1 (assuming a typical GRB spectrum).

Four uncatalogued sources were detected too far from the GRB position
to be likely afterglow candidates.

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/ToO_GRBs/00021910.

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