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GCN Circular 31924

GRB 220403C: Further Swift-XRT observations
2022-04-20T08:07:27Z (2 years ago)
Phil Evans at U of Leicester <>
A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU),
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. Melandri
(INAF-OAB), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB) and P.A.
Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed a second follow-up observation of GRB 220403C,
detected outside the BAT coded FOV by GUANO NITRATES (Aaron Tohuvavohu
et al. GCN Circ. 31824), and later triangulated by IPN (GCN Circ.
31877). This time the XRT pointed at the centre of the IPN error
region, collecting 2.5 ks of Photon Counting (PC) mode data between
T0+1311.3 ks and T0+1324.1 ks. 

Two uncatalogued X-ray sources have been detected, however neither of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if either, is
the afterglow. Details of these sources are given below:

Source 1:
  RA (J2000.0):  17.5547  =  01:10:13.12
  Dec (J2000.0): -56.2345  =  -56:14:04.2
  Error: 5.5 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (5.7 [+2.0, -1.6])e-3 ct s^-1   
  Distance: 46 arcsec from IPN position.
  Flux: (6.8 [+2.4, -2.0])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000.0):  17.9074  =  01:11:37.77
  Dec (J2000.0): -56.1775  =  -56:10:38.9
  Error: 9.7 arcsec (radius, 90% conf.)
  Count-rate: (5.0 [+3.2, -2.3])e-3 ct s^-1   
  Distance: 695 arcsec from IPN position.

We note that neither of these sources is consistent with the location
of the galaxy LEDA 3080270 which lies within the IPN error box.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at

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