GCN Circular 11026
Subject
GRB 100728B: Swift/UVOT Observations
Event
Date
2010-07-29T08:52:21Z (15 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates (MSSL-UCL) and D. C. Morris (GWU/GSFC) report on behalf of
the Swift/UVOT team:
The Swift/UVOT began observerving the field of GRB 100728B 101s
after the BAT trigger (Morris et al., GCN Circ. 11009). We detect the
optical afterglow in the white, v, b and u filters only.
The refined UVOT position is RA (J2000)= 163.48809, DEC
(J2000)=-45.47265,
which is equivalent to:
RA (J2000) = 02:56:13.467
Dec (J2000) = +00:16:52.18
with an estimated uncertainty of 0.52 arcsec (radius, 90% confidence).
This position is consistent with the XRT refined position (Evans et
al., GCN Circ 11017)
and with the optical afterglow positions reported by KAIT (Perley et
al., GCN Circ 11007, 11010 & 11024),
PROMPT (Ivarsen et al., GCN Circ 11008, 11011) & the SON-NM
observatory (Elenin et al., GCN Circ 11012).
The non-detection in the UV filters suggests a photometric redshift of
z~2.8.
Preliminary magnitudes and the 3 sigma upper limits are reported below
for
individual optical images and summed UV images.
Filter T_start(s) T_stop(s) Exposure Mag/3SigUL
###########################################################
white 101 251 147 17.43 +/- 0.08
white 4713 4913 197 20.62 +/- 0.22
v 3687 3887 197 20.19 +/- 0.56
b 4509 4709 197 20.47 +/- 0.33
u 4303 4503 197 19.90 +/- 0.28
uvw1 4098 6050 294 > 20.50
uvm2 3892 5529 393 > 20.52
uvw2 3482 5119 393 > 20.93
###########################################################
The above magnitudes are not corrected for the Galactic extinction
corresponding to a non-negligible reddening of E_{B-V} = 0.07 mag
(Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric system
described in Poole et al. (2008, MNRAS, 383,627).