GCN Circular 21074
Subject
Swift XRT observations of GRB 170424A
Event
Date
2017-05-06T16:23:20Z (9 years ago)
From
Boris Sbarufatti at INAF-OAB/IASFPA <boris.sbarufatti@brera.inaf.it>
B. Sbarufatti (INAF-OAB/PSU), P. A. Evans (U. Leicester) report on behalf of the Swift XRT team.
We report on Swift XRT observations of the field of the Fermi-LAT discovered GRB 170424A (N. Omodei et al. 2017, GCN 21032).
Swift performed an initial tiled observation of the LAT error circle (27 arcmin) using a 7-tile pattern (7-tile pattern 100% coverage radius: 24 arcmins, maximal coverage radius: 33 arcmins), 700 s of exposure/tile, on April 25th (P. A. Evans 2017, GCN 21034).
Three uncatalogued sources were detected:
Source# RA Dec Rate Exposure time
2 22h 52m 53.04s -45d10m43.5s 1.5+/-0.5E-2 cps 684s
3 22h 53m 10.51s -45d29m11.5s 1.9+/-0.6E-2 cps 677s
5 22h 52m 09.64s -45d02m43.3s 1.5+/-0.7E-2 cps 684s
On May 3rd and 4th further observations were performed to check for fading of the sources.
Source 2 was still detected without showing any evidence of fading.
Sources 3 and 5 were no more detected, but the 3-sigma upper limits are consistent with the earlier detections, within errors.
Source# Rate Exposure time
2 1.1+/-0.2E-2 cps 2.8 ks
3 < 1.4E-2 cps 3.1 ks
5 < 7.1E-3 cps 3.1 ks
We conclude that Source 2 is not the GRB afterglow, while the nature of Sources 3 and 5 remains uncertain.
All the quoted errors are at the 90% confidence level.
This circular is an official product of the Swift-XRT team.