GCN Circular 17751
Subject
GRB 150424A: Swift/UVOT Observations
Date
2015-04-24T15:03:18Z (10 years ago)
From
Frank Marshall at GSFC <femarsha@khamseen.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC) and A. P. Beardmore (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150424A
99 s after the BAT trigger (Beardmore et al., GCN Circ. 17743).
A source consistent with the position
of the suggested optical afterglow
(Perley and McConnell, GCN Circ. 17745)
is detected in the initial UVOT exposures.
The source remains nearly constant in 6 exposures with the
white filter starting 99 s after the trigger and ending
6786 s after the trigger. The magnitude is approximately that
reported by Perley and McConnell. This may be a detection
of the host galaxy.
The preliminary UVOT position is:
RA (J2000) = 10:09:13.38 = 152.30577 (deg.)
Dec (J2000) = -26:37:51.1 = -26.63086 (deg.)
with an estimated uncertainty of 0.6 arcsec. (radius, 90% confidence).
Preliminary detections and 3-sigma upper limit using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 99 6786 609 20.38 +/- 0.07
v 641 5881 432 >19.8
b 567 6701 432 20.71 +/- 0.21
u 311 5061 462 20.13 +/- 0.20
w1 690 6291 413 20.00 +/- 0.24
m2 4452 6086 393 19.91 +/- 0.29
w2 616 5677 216 20.03 +/- 0.31
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.06 in the direction of the burst
(Schlegel et al. 1998).
[GCN OPS NOTE(24apr15): Per author's request the missing minus sign
on the hh:mm:ss format of the value was added; the decimal-deg value was correct.]