GCN Circular 35650

M. Perri (SSDC & INAF-OAR), S. Dichiara (PSU), J.A. Kennea (PSU), A.
Tohuvavohu (U. Toronto), K.L. Page (U. Leicester), A.P. Beardmore (U.
Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (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 240128A in a series of observations tiled on the sky. The
total exposure time is 1.4 ks, distributed over 6 tiles; the maximum
exposure at a single sky location was 460 s. The data were collected
between T0+46.4 ks and T0+52.4 ks, and are entirely in Photon Counting
(PC) mode. 

One uncatalogued X-ray source has been detected, it is below the RASS
limit and shows no definitive signs of fading. Therefore, at the
present time we cannot confirm this as the afterglow. Details of this
source are given below:

Source 1:
  RA (J2000.0):  140.1536  =  09:20:36.87
  Dec (J2000.0): -5.2004  =  -05:12:01.5
  Error: 8.8 arcsec (radius, 90% conf.)
  Count-rate: 0.0149 [+0.0080, -0.0059] ct s^-1   
  Distance: 1224 arcsec from MAXI position.
  Flux: (2.9 [+1.6, -1.2])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

A catalogued source was also detected.

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_GRB00120.

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