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[vsnet-grb-info 892] (fwd) GRB 20030329, more observation data, astrometry (Monard)



(fwd) GRB 20030329, more observation data, astrometry (Monard)

Tabulated report

Contact name: Berto Monard
Contact e-mail: bmonard@mweb.co.za
Observer: Berto Monard / MLF
Site Name: Bronberg Observatory
Nearest town: Pretoria / South Africa
Site latitude: 25deg 55min South
Site longitude: 28deg 27min East
Site elevation: 1590m
Telescope type: SCT / 30cm
Telescope focal ratio: f/4.2 effectively
CCD camera: SBIG ST-7E
CCD detector: KAF-0401E
CCD dimensions: 765x510 pixels
CCD pixel scale: 1.52 arcsec/pixel
F.O.V: 18 arcmin E-W x 12.5 arcmin N-S
GRB object name: GRB 030329
Observation date: 20030329 UT
Observation start time: 17 15 UT     
Observation end time: 23 37 UT        
Exposure time per frame: 45 sec
Number of stacked frames: results of timeseries photometry on optical =
transient, no stacking
Filters used: unfiltered / CR
Processed: FF, DS, AIP4WIN reduction
Estimated seeing: 4 arcsec FWHM
Limiting magnitude: 17.0CR to 18.0CR per frame UCAC1 differentials
Sky conditions: clear, cloud passages halfway measurements, average =
seeing


Details of observation:

The reported bright optical transient of GRB 20030329 was monitored over 
a duration of just under 6.5 hours continuously with 60 sec imaging 
cycles.

Using differential photometry based on one Tycho II star just South of 
the field, the optical transient faded from 13.8CR to 14.7CR over the 
reported period. It is possible that these magnitudes are about 0.3 to 
0.4 magnitude too bright.
It is not impossible that QPOs (at 0.3h and/or 0.95h) are present. These 
periods seem to shorten towards the end of the run...

A polynomial fit of the second degree (quite good at 0.99963) through 
the lightcurve produced the following fading rates:
0.19CR/hour around JD ..2728.22
0.11CR/hour around JD ..2728.48

At these rates the OT will be around for quite sometime still.

Other measurements:

Astrometry on a stack of the best images gave the following (2000) 
position for the transient, traceable to USNO-A2.0:

10 44 50.05 +21 30 10.5

A .fts image will be sent to A Price at aaronp@aavso.org .
The photometric run data and the image can be made available.


This report can be cited.


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