TITLE:   GCN CIRCULAR
NUMBER:  40570
SUBJECT: GRB 250527B: Swift-XRT observations
DATE:    25/05/29 09:30:00 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

J.A. Kennea (PSU), D.N. Burrows (PSU), M.A. Williams (PSU), A.P.
Beardmore (U. Leicester), J.P. Osborne (U. Leicester), B. Sbarufatti
(INAF-OAB), C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB) and P.A. Evans
(U. Leicester) reports on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 250527B in a series of observations tiled on the sky.  The
total exposure time is	3.5 ks, distributed over 12 tiles; the maximum
exposure at a single sky location in the tiling was 620 s. The data
were collected between T0+57.5 ks and T0+65.2 ks, and are entirely in
Photon Counting (PC) mode. 

No X-ray sources have been detected. The 3-sigma upper limit in the
field (not including the regions where the tiles overlap) ranges from
~0.02 to ~0.05 ct s^-1, corresponding to a 0.3-10 keV observed flux of
9.2e-13 to 2.0e-12 erg cm^-2 s^-1 (assuming a typical GRB spectrum).

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00136.

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