TITLE:   GCN CIRCULAR
NUMBER:  25399
SUBJECT: GRB 190816A: Swift-XRT observations
DATE:    19/08/19 08:14:53 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), A.
Tohuvavohu (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB) and K. L.
Page (U Leicester) report on behalf of the Swift-XRT team:

We have analysed 3.8 ks of Photon Counting (PC) mode XRT data for the
Swift/BAT-detected burst GRB 190816A (Page et al. GCN Circ. 25368),
collected between T0+141.7 ks and T0+216.6 ks. 

One uncatalogued X-ray source has been detected consistent with being
within 296 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 4:
  RA (J2000.0):  341.1897  =  22:44:45.53
  Dec (J2000.0): -29.7577  =  -29:45:27.8
  Error: 4.8 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (8.1 [+1.8, -1.7])e-3 ct s^-1   
  Distance: 64 arcsec from Swift/BAT position.
  Flux: (2.67 [+0.60, -0.56])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/00920783.

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