[vsnet-grb-info 167] Revised Photometry of the Optical Afterglow of GRB 020405

[GCN Circulars <gcncirc@lheawww.gsfc.nasa.gov>]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1336
SUBJECT: Revised Photometry of the Optical Afterglow of GRB 020405
DATE:    02/04/07 13:07:51 GMT
FROM:    Jens Hjorth at U.Copenhagen  <jens@astro.ku.dk>

Revised Photometry of the Optical Afterglow of GRB 020405


J. Hjorth (U. Copenhagen) reports:

The calibration of the PSF photometry reported in GCN #1329 relied on a
misidentification of the USNO A2.0 star 0525_16813005 with 0525_16812476.
Calibration to 0525_16813005 yields R = 19.8 and B - R = 1.0 at April 6.21 UT,
consistent with the reports of Palazzi et al. (GCN #1328), Price et al.
(GCN #1333), and Gal-Yam et al. (GCN #1335). The systematic error in these
values is of the order of +- 0.3 mag. I apologize for the impact this error
may have had on follow-up strategies and thank Javier Gorosabel and Paul Price
for pointing out the problem.

Additional data taken with the DK1.5m between Apr 7.13 and Apr 7.37 confirm
the continued fading of the source. A careful analysis of these data is in
progress!

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