GCN Circular 11948
Subject
GRB 110420A Swift/UVOT Observations
Event
Date
2011-04-21T10:10:04Z (15 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates (MSSL-UCL) & V. Mangano (INAF-IASFPA) report on behalf of the Swift-UVOT team
The Swift/UVOT began settled observations of the field of GRB 110420A 97s
after the trigger (Mangano et al., GCN Circ. 11941). We detect a source
at a refined position of RA(J2000), DEC(J2000)= 2.16363deg,-37.88664deg.
This is equivalent to:
RA (J2000) 00:08:39.27
Dec (J2000) -37:53:11.9
with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence).
This is consistent with the position of the X-ray afterglow
(Beardmore et al., GCN Circ. 11942). The afterglow is detected in
all filters providing a photometric redshift limit of z~<1.6.
Preliminary magnitudes using the UVOT photometric system (Poole et al. 2008,
MNRAS, 383, 627) for the finding chart (FC) and summed exposures at the
location of the optical afterglow are:
Filter T_start(s) T_stop(s) Exp(s) Mag
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wh (FC) 97 247 147 17.81 +/- 0.05
wh 761 781 19 18.10 +/- 0.17
u (FC) 309 559 246 17.46 +/- 0.07
u 712 732 19 17.96 +/- 0.36
v 811 831 19 18.20 +/- 0.67
b 737 757 19 18.04 +/- 0.28
uvw1 688 707 19 17.08 +/- 0.24
uvm2 663 683 19 17.73 +/- 0.41
uvw2 614 634 19 17.91 +/- 0.35
#####################################################
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).