TITLE:   GCN CIRCULAR
NUMBER:  19641
SUBJECT: GRB 160629A: Swift-XRT afterglow detection
DATE:    16/07/01 18:34:27 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),
D.N. Burrows (PSU), K.L. Page (U. Leicester), B. Mingo (U. Leicester),
A.P. Beardmore (U. Leicester), A. Maselli  (INAF-IASFPA), A. Melandri
(INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team:

Swift-XRT has performed follow-up observations of the INTEGRAL-detected
burst GRB 160629A (Gotz et al. GCN Circ. 19621), collecting 2.6 ks of
Photon Counting (PC) mode data between T0+77.1 ks and T0+89.3 ks. 

An uncatalogued X-ray source is detected within the 3-sigma INTEGRAL
error region and is  believed to be the afterglow. Using 1633 s of PC
mode data and 1 UVOT image, we find an enhanced XRT position (using the
XRT-UVOT alignment and matching UVOT field sources to the USNO-B1
catalogue): RA, Dec = 4.86537, +76.96703 which is equivalent to:

RA (J2000): 00h 19m 27.69s
Dec(J2000): +76d 58' 01.3"

with an uncertainty of 3.4 arcsec (radius, 90% confidence). This
position is 111 arcsec from the INTEGRAL position.  We cannot determine
at the present time whether the source is fading. 
Since this position is consistent with the one reported for the optical
afterglow (Klotz et al. GCN Circ 19622; Sokolov et al. GCN Circ 19623;
Rebolo et al. GCN Circ. 19638), we propose this source as the X-ray
afterglow of GRB 160629A. 

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020676.
The results of the full analysis of the XRT observations are available
at http://www.swift.ac.uk/ToO_GRBs/00020676.

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