GCN Circular 8179
Subject
GRB 080903: Swift/UVOT Observations
Date
2008-09-03T19:06:16Z (16 years ago)
From
Frank Marshall at GSFC <marshall@milkyway.gsfc.nasa.gov>
F.E. Marshall (NASA/GSFC) and D. Grupe (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT observed the field of GRB 080903 starting 75 s after
the BAT trigger (Grupe et al., GCN Circ. 8169). A source is
detected in the initial exposure in the V filter at the position
of the optical afterglow (de Ugarte Postigo et al., GCN Circ. 8172).
There is also a marginal (1.8 sigma) detection in the initial exposures
with the U filter. A valid detection in the U filter would
indicate a redshift of less than 3.3.
The magnitudes and 3-sigma upper limits in the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) for detecting
a source in the first finding chart (FC) exposure and
subsequent co-added exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
v (FC) 75 475 393 19.8 +/- 0.24
v 595 28705 2596 >21.5
b 555 12429 1307 >21.8
u 530 829 58 20.0 +/- 0.47
u 4906 34528 3049 >21.8
uvw1 506 7268 551 >21.0
uvm2 481 7160 655 >20.7
uvw2 571 6750 452 >21.2
The values quoted above are not corrected for the Galactic extinction due
to the reddening of E(B-V) = 0.22 in the direction of the burst
(Schlegel et al. 1998).