GCN Circular 9435
Subject
GRB090529: UVOT/Swift detection of a brightening optical afterglow
Date
2009-05-29T22:12:44Z (15 years ago)
From
Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>
P. Schady (MSSL-UCL), T. Sakamoto (NASA/UMBC), S. T. Holland
(CRESST/GSFC/USRA) and F. E. Marshall (NASA/GSFC) report on behalf of the
Swift UVOT team:
The Swift/UVOT began settled observations of the field of GRB 090529 206s
after the BAT trigger (Sakamoto et al., GCN Circ. 9430) and no new source
was detected within the XRT position in the first white finding chart (fc)
(Sakamoto et al., GCN Circ. 9430; Holland et al., GCN Circ. 9432).
However, a new source is detected within the refined XRT error circle
(Osborne et al., GCN Circ. 9433) in a second white finding chart, taken at
883s after the BAT trigger, as well as in a co-added b-band exposure at
RA (J2000) 14:09:52.56 = 212.46892 (deg)
Dec (J2000) +24:27:32.2 = +24.45892 (deg)
with an estimated uncertainty of 0.7 arcsec (radius, 90% confidence,
statistical + systematic). This source detection is consistent with the
white band detection reported by Xin et al. (GCN Circ. 9431). We note that
there is weak evidence that the source could be extended.
The magnitudes and 3-sigma upper limits for the observations currently
available are as follows:
Filter T_start(s) T_stop(s) Exp(s) Mag/3-sigma UL
white_fc1 206 355 147 > 21.09
white_fc2 883 1032 147 20.81 +/- 0.22
white 1185 2587 175 21.55 +/- 0.31
v 363 2637 253 > 20.24
b 461 2564 233 20.97 +/- 0.36
b 2716 2824 107 > 20.70
u 436 2691 253 > 20.87
uvw1 412 2667 156 > 20.60
uvm2 387 2661 253 > 20.20
uvw2 510 2594 253 > 20.65
The values quoted above are not corrected for the Galactic extinction due
to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel
et al. 1998). The photometry is on the UVOT photometric system described
in Poole et al. (2008, MNRAS, 383, 627).