GCN Circular 6528
Subject
GRB 070611: Watcher Observations
Event
Date
2007-06-13T17:57:50Z (18 years ago)
From
Gary Melady at UCD <gmelady@bermuda.ucd.ie>
Gary Melady, John French, (University College Dublin), Petr Kubanek,
Martin Jelinek (IAA CSIC Granada, Spain)
on behalf of the Watcher collaboration report:
The Watcher 40cm robotic telescope, located at Boyden Observatory, South
Africa, began imaging the field of GRB 070611 (Stroh et al., GCN
6494) at 01:58:33 UT, 1m 17s after the Swift trigger (40s after receipt of
the GCN notice).
We combined our initial series of 10s exposures to create a 440s unfiltered
image with an exposure mid-time of 2:05:21 (501s after the burst). This shows
no new source in the XRT error box (Stroh et al., GCN 6496) down to an R-band
limiting magnitude of approx. 19.2 (in comparison to USNO-B1). Later images show
a faint, uncatalogued source within the XRT error box coincident with the ROTSE
detection (Rykoff et al., GCN 6497).
These observations are summarised below:
mean time UT t-t0(s) exp(s) Rmag
--------------------------------------------------------
02:18:56 1316 900 19.08 +/- 0.24
02:32:48 2148 210 18.53 +/- 0.24
02:37:11 2411 180 19.12 +/- 0.30
02:42:46 2746 240 18.99 +/- 0.26
02:48:54 3144 330 19.19 +/- 0.24
The source is not detected in subsequent observations down to an R-band limiting
magnitude of approx 19.2.
The field was no longer observed after 02:54 due to the system's
incorrect handling of the retracted XRT position.
This message may be cited.