GCN Circular 6160
Subject
GRB 070227: Swift/UVOT Upper Limits
Date
2007-02-28T23:52:35Z (18 years ago)
From
Shashi Pandey at MSSL <sbp2@mssl.ucl.ac.uk>
S. B. Pandey (UCL-MSSL) and C. Pagani (PSU) report on behalf of
the Swift/UVOT Team:
The Swift/UVOT started observing the field of GRB 070227 (trigger 262347)
56680 s after the BAT trigger (Pagani et al., GCN Circ. 6156). UVOT
observations started late because the BAT observation did not result
in an automated response, but was found during the ground analysis.
The 3-sigma upper limits for detecting a source inside the XRT error
circle (Pagani, Grupe & Burrows, GCN Circ. 6157) in the co-added
exposures are:
Filter T_start T_stop Exp(s) Mag (3-sigma upper limit)
---------------------------------------------------------------
V 56680 57586 885 20.90
B 63392 64113 702 21.58
U 62480 63386 885 21.31
UVW1 61573 62473 886 21.17
UVM2 57592 58329 726 21.34
UVW2 55773 56673 886 21.04
---------------------------------------------------------------
Caution should be taken due to the presence of a nearby bright star. The
XRT error circle lies lies within the wings of the PSF of the bright star
in all the UVOT frames. This complicates the photometry, so these limits
could possibly be underestimated.
The values quoted above are not corrected for the expected Galactic
extinction E_{B-V} = 0.34 mag towards the direction of the burst
(Schlegel et al. 1998).