GCN Circular 9342
Subject
GRB 090510: UVOT refined analysis
Event
Date
2009-05-10T16:59:54Z (17 years ago)
From
Paul Kuin at MSSL <npkuin@googlemail.com>
N. P. M. Kuin (MSSL/UCL) and E.A. Hoversten (PSU) report on
behalf of the Swift UVOT team.
The Swift UltraViolet/Optical Telescope (UVOT) began observations of
the short hard burst GRB 090510 (Swift BAT trigger number 351588;
Hoversten et al. GCN Circ. 9331) on May 10, 2009, at 00:24:24 UT,
80 seconds after the BAT trigger with a settling exposure in the
UVOT v filter.
A new optical source was found by the UVOT (Marshall and Hoversten,
GCN Circ. 9332) for which we have a refined position (based on
matching the UVOT field sources to the USNO-B1 catalogue) of
RA, DEC = 333.55208, -26.58311, which is equivalent to:
RA = 22:14:12.5, DEC = -26:34:59.2, with an uncertainty of 1.5"
(90% confidence). The refined UVOT position is offset 1.6" from
the refined XRT position (Goad et al., GCN Circ. 9339) and is
consistent with the revised NOT position (Malesani, GCN Circ. 9340)
to within 0.2".
GRB 090510 is detected in all UVOT filters, except perhaps in b,
which implies that the redshift is less than about 1.5. The
emission is seen to rise to a peak around 600s after the trigger.
The initial magnitude observed in the UVOT filters are given below:
Filter Tstart(s) Tstop(s) Exposure(s) Magnitude
wh 97 247 147.4 19.63 +/- 0.17
wh 588 608 19.5 18.76 +/- 0.22
wh 1167 1526 58.3 19.16 +/- 0.20
v 80 1410 97.3 18.46 +/- 0.33
b 564 1502 97.2 >19.62 (2.2 sigma)
u 712 1477 323.6 19.05 +/- 0.17
uvw1 687 1452 75.9 18.61 +/- 0.27
uvm2 662 1434 93.7s 18.10 +/- 0.22
uvw2 614 1552 115.4s 18.31 +/- 0.18
The values quoted above are on the UVOT Photometric System
(Poole et al, 2008, MNRAS 383,627). They are not corrected for the
expected galactic reddening of E(B-V) = 0.020 in the direction of
the burst (Schlegel et al. 1998).