GCN Circular 3596

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T. Poole (MSSL), D. Grupe (PSU), A. Breeveld (MSSL),
L. Angelini (GSFC-JHU), J. Greiner (MPE) on behalf of the
Swift UVOT team

The Swift Ultra-Violet/Optical Telescope (UVOT) began
observations of GRB050712 (Grupe et al. GCN 3573
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 ; E.Rol
et al. GCN 3575
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 ) on 12th July 2005 at 14:02:58 UT. We detect
a source inside the XRT error circle (Falcone et al.
GCN 3574
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 ) in the V and U bands. It initially fades, then
brightens before fading below the detection threshold. It is
not detected in the UV filters. No B observations were taken
because of a bright source in the field of view violating the
UVOT count rate limits.

The aperture for optical observations (V and U) was 6 arcsec
and for the UV 12 arcsec. The limiting magnitudes are given
to a 3 sigma limit.

V filter

start  exposure mid        magnitude
time   time     time
after         =09after
burst           burst
(s)    (s)      (s)
164    100      214        17.97 =B1 0.09    - source detection
313    10       318        17.85 =B1 0.20    - source detection
383    10       388        18.69 =B1 0.20    - source detection
455    10       460        18.13 =B1 0.20    - source detection
526    10       531        18.04 =B1 0.20    - source detection
597    10       602        17.99 =B1 0.20    - source detection
668    49       693        17.83        - limiting magnitude
1207   100      1257       18.01        - limiting magnitude
11414  900      11864      22.15        - limiting magnitude



U filter

start  exposure mid        magnitude
time   time     time
after           after
burst           burst
(s)    (s)      (s)
282    10       287        17.92 =B1 0.20     - source detection
353    10       358        17.82        - limiting magnitude
425    10       430        17.75        - limiting magnitude
425    10       430        19.47 =B1 0.20    - source detection
496    10       501        18.16 =B1 0.20    - source detection
639    49       664        18.50        - limiting magnitude
996    100      1051       18.74        - limiting magnitude
6477   663      6809       19.83        - limiting magnitude



UVW1

start  exposure mid        magnitude
time   time     time
after           after
burst           burst
(s)    (s)      (s)
268    107      322        18.49        - limiting magnitude
1970   833      2387       19.62        - limiting magnitude




UVM2 - limiting magnitudes

start  exposure  mid        magnitude
time   time      time
after            after
burst            burst
(s)    (s)       (s)
325    98        374        19.05        - limiting magnitude
1310   46        1333       18.36        - limiting magnitude
4663   1447      723        20.36        - limiting magnitude




UVW2 - limiting magnitudes

start  exposure  mid        magnitude
time   time      time
after            after
burst            burst
(s)    (s)       (s)
298    98        347        19.05        - limiting magnitude
1102   100       1152       20.15        - limiting magnitude
10447  900       10897      21.57        - limiting magnitude




We caution that the instrument is not yet fully calibrated and that the
magnitude limits presented here may need to be refined.

This message may be cited.

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