TITLE:   GCN CIRCULAR
NUMBER:  28626
SUBJECT: Swift-BAT trigger 1000255: XRT afterglow detection of GRB 201014A
DATE:    20/10/15 09:45:28 GMT
FROM:    Valerio D'Elia at ASDC  <valerio.delia@ssdc.asi.it>

V. D’Elia (SSDC), E. Ambrosi, A. D’Aì (INAF-IASFPA) and P.A. Evans (U. Leicester)
report for the Swift-XRT team:

We have analysed 1.5 ks of XRT data for the Swift trigger 1000255 (Ambrosi et al. GCN Circ. 28623), from 156 s to 5.2 ks after the  BAT trigger. The data are entirely in Photon Counting (PC) mode. We detect a bright (2.2E-1 cts/s), fading, uncatalogued X-ray source at the UVOT-enhanced position:

20.79619, 27.66024 which is equivalent to:

RA (J2000):  01 23 11.09
Dec (J2000): +27 39 36.9

with an uncertainty of 1.8 arcseconds (radius, 90% containment). This location is 3.3 arcminutes from the BAT onboard position, at the margin of the BAT error circle. This position was outside of the central window which is telemetered promptly, hence the source was not seen in the initial real-time analysis

Given that no catalogued X-ray sources are present within 5 arc minutes from the XRT position, we conclude that Swift-BAT trigger 1000255 is not due to noise but indeed is a GRB, and the reported source is the X-ray afterglow of GRB 201014A.

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