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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).
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