GCN Circular 9948
Subject
GRB090926A: Swift/UVOT observations
Event
Date
2009-09-27T12:41:56Z (17 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates (MSSL-UCL) and L. Vetere (PSU) report on behalf
of the Swift/UVOT team:
The Swift/UVOT began observerving the field of Fermi GRB 090926A
47ks after the Fermi GBM and LAT trigger (Bissaldi., GCN Circ. 9933;
Uehara ., GCN Circ. 9934). We detect a fading optical afterglow in
white,
v and u filters at the position reported by UVOT (Gronwall et al.,
GCN Circ. 9938) and Skynet/PROMPT (Haislip et al., GCN Circ 9937).
The lightcurve appears to rebrighten from 70ks to the end of
current observations.
Preliminary magnitudes are reported below.
Filter T_start(s) T_stop(s) Exposure Mag Err
-------------------------------------------------------
white 46977 47341 358 18.71 +/- 0.04
white 69902 70369 459 19.32 +/- 0.05
v 47348 47712 358 18.45 +/- 0.16
u 46608 46972 358 18.21 +/- 0.07
u 69429 69896 459 18.85 +/- 0.09
u 86050 86613 554 18.52 +/- 0.07
-------------------------------------------------------
The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0.02 mag (Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT flight system
described in Poole et al. (2008, MNRAS, 383,627).