GCN Circular 3129
Subject
GRB 050319: Swift-UVOT detection of the afterglow
Date
2005-03-21T00:38:06Z (20 years ago)
From
Martin Still at NASA/GSFC Swift SSC <Martin.Still@gsfc.nasa.gov>
P. Boyd (GSFC/UMBC), S. T. Holland, M. Still (GSFC/USRA), W. Landsman
(GSFC), S. Hunsberger (PSU), A. Breeveld (MSSL), P. Roming (PSU), K.
Mason, P. Schady (MSSL), M. Ivanushkina (PSU), T. Poole (MSSL), C.
Gronwall (PSU) A. Blustin (MSSL), P. Brown (PSU), S. Rosen, K. McGowan
(MSSL), S. Koch (PSU), M. Carter, H. Huckle, M. De Pasquale (MSSL), P.
Broos (PSU), T. Kennedy, P. Smith, B. Hancock (MSSL), H. Krimm
(GSFC/USRA), J. Nousek (PSU), N. Gehrels (GSFC), on behalf of the Swift
UVOT team.
The Swift Ultra-Violet/Optical Telescope (UVOT) began
settled observations of the field of GRB 050319 (Krimm
et al; GCN 3117) at 09:32:48 UT, 90 after the BAT
trigger. A comparison of the 100s finding chart (with
mid-exposure 140s after the trigger) against the
Digitized Sky Survey reveals a new source inside the BAT
and XRT error circles at:
RA = 10h 16m 47.76(3)s Dec = +43d 32m 54.9(5)s J2000
and consistent with the ROTSE-IIIb position reported by
Rykoff et al. (GCN 3116) The V band magnitude is V =
17.5(1).
The UVOT obtained a series of images of this burst with
a variety of integration times. Mid-exposure times,
Delta-T, with respect to the BAT trigger at 09:31:18 UT
are measured in seconds. Observations with the V and B
filters are listed below:
Delta-T Exposure(s) Filter Mag
140 100 V 17.5 (Finding Chart)
380 80 B 18.8
600 80 V 18.4
1030 100 B 18.9
1250 100 V 19.2
5400 900 B 20.9
7080 700 V 20.2
17000 900 B 21.2
18700 700 V 20.6
No signal was detected in the U band in a total exposure
time of 90s centered approximately 600s after the
trigger with an upper limit of U = 19.
We caution that the absolute magnitude scale is based on
ground calibration and will require confirmation in
flight.