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GCN Circular 21047

GRB 170428A: Swift-XRT refined Analysis
2017-04-28T21:19:32Z (7 years ago)
Andy Beardmore at U Leicester <>
A.P. Beardmore	and  P.A. Evans (U. Leicester)	report on behalf of the
Swift-XRT team:

We have analysed 4.2 ks of XRT data for GRB 170428A, from 697 s to 17.2
ks after the  BAT trigger. The data are entirely in Photon Counting
(PC) mode. Using 1475 s of PC mode data and 2 UVOT images, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 330.07813, +26.91580
which is equivalent to:

RA (J2000): 22h 00m 18.75s
Dec(J2000): +26d 54' 56.9"

with an uncertainty of 2.3 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.03 (+0.32, -0.29).

If the light curve continues to decay with a power-law decay index of
1.03, the count rate at T+24 hours will be 7.5 x 10^-4 count s^-1

The results of the XRT-team automatic analysis are available at

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