GCN Circular 29827

J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), T.
Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini
(INAF-OAB), B. Sbarufatti (PSU) 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-detected burst GRB 210413B (Swift/BAT did not successfully
trigger on GRB 210413B et al. GCN Circ. 29819
Not found
 
 
), collecting 4.9 ks of
Photon Counting (PC) mode data between T0+185.0 ks and T0+206.7 ks. 

One uncatalogued X-ray source has been detected consistent with being
within 394 arcsec of the Swift/BAT position, 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):  182.5333  =  12:10:7.98
  Dec (J2000.0): +56.0497  =  +56:02:59.0
  Error: 5.7 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (4.5 +/- 1.2)e-3 ct s^-1	 
  Distance: 309 arcsec from Swift/BAT position.
  Flux: (1.42 +/- 0.39)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Three 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/00021428.

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