[vsnet-grb-info 5705] GRB 080303: Swift/UVOT follow-up of afterglow detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7360
SUBJECT: GRB 080303: Swift/UVOT follow-up of afterglow detection
DATE:    08/03/03 23:18:28 GMT
FROM:    Alice Breeveld at MSSL-UCL  <aad at mssl.ucl.ac.uk>

A.A. Breeevld (MSSL/UCL) and T. Sakamoto (GSFC/UMBC) report on behalf 
of the Swift UVOT team:

The Swift/UVOT observed the burst GRB080303 (Sakamoto et al. GCN circ 
7351) starting with the finding chart exposure in white, 81s after the 
BAT trigger. The afterglow is detected at the enhanced XRT position 
(Evans et al. GCN circ 7356) in all filters except uvm2. In white it is 
detectable until at least 6600s after the trigger. The brightness 
increases until about 700s after the burst, then fades with an 
estimated temporal slope in the v filter of alpha= 0.9

The initial UVOT magnitudes (in the UVOT photometric system; Breeveld 
et al. GCN circ 6614) and 3 sigma upper limts from single exposures are 
as follows:

Filter	   Tstart(s)    Tstop(s)    Exp(s)   Mag      error(mags)
white    81            180             99.8      18.48    0.08
              682           691             9.8        18.19    0.19
              836           845             9.8        18.46    0.24
              880           979             99.8      18.88    0.11
             5195          5394          199.8    20.79    0.38
             6632           6831         199.8    20.72    0.35
v         187             586             399.8    18.03   0.08
             722             741            19.8       17.74   0.3
             987            1095           108.1    19.06    0.3
             5607          5806           199.8    19.76   0.38
b           667           676               9.8       18.59   0.36
               821           830              9.7         >18.74  (UL)
             4991          5190           199.8      >20.86  (UL)
             6427          6626           199.8     20.26   0.27
u           642             661             19.8     18.23    0.32
               797           816              19.8     17.99    0.26
             4785          4984            199.8    19.4     0.22
             6221          6420            199.8    20.33    0.41
uvw1    618            637             19.8        >18.1  (UL)
               771            790             19.7      17.83    0.38
              4581          4780            199.8   19.84    0.43
              6016          6215             199.8      >20.18 (UL)
uvm2    593            612               19.8        >17.58 (UL)
               746            765               19.8         >17.61 (UL)
               4375          4574            199.8       > 19.69 (UL)
                5811         6010            199.8      >19.76  (UL)
uvw2     698              717             19.8       >18.01 (UL)
                 851            870              19.8       17.82   0.37
               5401          5600            199.7       19.76 0.33
               6838          6875              37.6        >18.7  (UL)

The values quoted above are not corrected for the expected Galactic 
extinction corresponding to a reddening of E(B-V)=0.192 mag in the 
direction of the burst (Schlegel et al. 1998).