J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore
(U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) ,
M. Capalbi (INAF-IASFPA), J. D. Gropp (PSU), J.A. Kennea (PSU), A.
Tohuvavohu (U. Toronto) and M. Stamatikos (OSU) report on behalf of the
We have analysed 2.7 ks of Photon Counting (PC) mode XRT data for the
Swift-BAT-detected burst GRB 210218A (Stamatikos et al. GCN Circ.
29537), collected between T0+170 ks and T0+210 ks s.
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
RA (J2000.0): 47.3236 = 03:09:17.67
Dec (J2000.0): +35.3240 = +35:19:26.5
Error: 4.8 arcsec (radius, 90% conf.)
Count-rate: (5.6 [+2.0, -1.6])e-3 ct s^-1
Distance: 164 arcsec from Swift-BAT position.
Flux: (1.03 [+0.36, -0.29])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
Two 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
This circular is an official product of the Swift-XRT team.