GCN Circular 8359
Subject
GRB081011: UVOT detection of an optical afterglow
Event
Date
2008-10-11T17:57:02Z (17 years ago)
From
Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>
P. Schady (MSSL-UCL) and D.Grupe (PSU) report on behalf of the Swift/UVOT
team:
The Swift/UVOT observed the field of GRB 081011 (Grupe et al., GCN Circ.
8355) with settled exposures starting 99s after the trigger. A new fading
source is detected in the white and u-band finding chart (fc) exposures
and marginally in a co-added b-band exposure at
RA(J2000) = 14:41:22.627 (220.34428)
Dec(J2000) = +33:32:37.12 (+33.54364)
consistent with the XRT position (Kennea et al., GCN Circ. 8358). These
detections imply an upper limit on the redshift of z < ~3.8. The source is
decaying with an approximate optical decay rate of alpha~1.1 (where the
afterglow flux is proportional to t^-alpha).
The detections and 3 sigma upper limits in the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) are:
Filter������������T_start T_stop�� Exp�� Mag or 3-sigma UL
������������������������(s)�� �� ��(s)���� �� (s)
========================================================
white (FC)����99�� �� ����249����������145.8�� 19.25 +/- 0.08
white��������������537���� �� 1878��������283.5�� ��20.33 +/- 0.13
u (FC)������������257���� �� 507�������� 245.8���� 18.62 +/- 0.10
u����������������������660���� �� 2003������ 155.6���� 19.91 +/- 0.30
v�������������������� 586���� �� 7371������ 548.8�� ��> 20.29
b����������������������512���� �� 6756���� 351.4������21.13 +/- 0.39
uvw1����������������636�������� 7781���� 548.8���� > 20.96
uvm2������������ ��611���� �� 7576�� �� 548.9�� > 20.74
uvw2���������� �� 562�������� 7167���� 548.8������> 21.06
The values quoted above are not corrected for the expected Galactic
extinction corresponding to a reddening of E(B-V) = 0.01 mag in the
direction of the burst (Schlegel et al. 1998).