TITLE:   GCN CIRCULAR
NUMBER:  29908
SUBJECT: GRB 210323B: Swift-XRT observations
DATE:    21/04/27 17:32:50 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), A. D'Ai
(INAF-IASFPA), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N.
Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),
A.P. Beardmore (U. Leicester) and P.A. Evans (U. Leicester) report on
behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-GUANO-detected burst GRB 210323B (James DeLaunay et al. GCN
Circ. 29701), collecting 10.2 ks of Photon Counting (PC) mode data
between T0+100.8 ks and T0+1300 ks. 

One uncatalogued X-ray source has been detected consistent with being
within the Swift/BAT localization, 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):  259.6867  =  17:18:44.80
  Dec (J2000.0): +15.6339  =  +15:38:02.2
  Error: 4.6 arcsec (radius, 90% conf.)
  Count-rate: (1.18 [+0.71, -0.52])e-3 ct s^-1	 
  Distance: 173 arcsec from Swift/BAT position.

Seven uncatalogued sources were also 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/00021426.

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