GCN Circular 37218

P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), S. Dichiara (PSU),
J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E.
Ambrosi  (INAF-IASFPA)	and P.A. Evans (U. Leicester) reports on behalf
of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
SVOM/Eclairs-detected X-ray transient GRB 240819A (GCN 37208
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  Coleiro et
al.), collecting 2.0 ks of Photon Counting (PC) mode data between
T0+19.7 ks and T0+26.6 ks. 

Two uncatalogued X-ray sources have been detected, however none of them
is above the RASS limit or shows definitive signs of fading. Therefore,
at the present time we cannot identify which, if any, is the afterglow.
Details of these sources are given below:

Source 1:
  RA (J2000.0):  311.0531  =  20:44:12.74
  Dec (J2000.0): +49.6821  =  +49:40:55.5
  Error: 6.6 arcsec (radius, 90% conf.)
  Count-rate: (3.4 [+2.0, -1.5])e-3 ct s^-1   
  Distance: 336 arcsec from SVOM/Eclairs position.
  Flux: (9.8 [+5.7, -4.2])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000.0):  310.9464  =  20:43:47.14
  Dec (J2000.0): +49.5140  =  +49:30:50.3
  Error: 5.8 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0111 [+0.0035, -0.0029] ct s^-1   
  Distance: 636 arcsec from SVOM/Eclairs position.
  Flux: (4.4 [+1.4, -1.1])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Moreover Source 2, separated by 5.525" from EP J204347.6+493054 (GCN
37206
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  Li et al.), has not been detected from a previous observation
performed by Swift at MJD 54638.495 with a 3 sigma upper limit of
2.9e-03 ct s^-1.

Swift will perform further ToO observations to assess the nature of 
this transient.


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/00021702.

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