TITLE:   GCN CIRCULAR
NUMBER:  9032
SUBJECT: GRB 090323: UVOT Detection of Afterglow
DATE:    09/03/24 19:40:58 GMT
FROM:    Erik Hoversten at Swift/Penn State  <hoversten@astro.psu.edu>

E. A. Hoversten (PSU) reports on behalf of the Swift UVOT team:

The Swift/UVOT began settled observations of the field of
GRB 090323 70 ks after the Fermi LAT trigger (Ohno et al., GCN 9021).
The afterglow is detected in the UVOT white filter at:

     RA (J2000)  12:42:50.29
    Dec (J2000)  17:03:11.8

with an estimated uncertainty of 0.8 arcsec (radius, 90% confidence).
This position is consistent with the UVOT enhanced XRT position (Kennea
et al., GCN 9024) as well as the optical position determined by
GROND (Updike et al., GCN 9026)  The afterglow candidate does not
appear in the DSS images.  Photometry from the second set of Swift
observations may be indicative of fading, but is not deep enough to be
conclusive.

UVOT magnitudes and 3-sigma upper limits are reported in the following
table:

Filter   T_start   T_stop   Exp(s)  Mag (3-sigma upper limit)
-----------------------------------------------------
WHITE     70287     75931    1196   21.66 +/- 0.28
WHITE    115572    121460     601      > 21.60
V         70667     76062     517      > 19.88
U         69906     75078    1200      > 21.02

The quoted upper limits have not been corrected for the expected
Galactic extinction along the line of sight of E(B-V) = 0.03 mag.
All photometry is on the UVOT photometric system described in Poole et al.
(2008, MNRAS, 383, 627).