GCN Circular 5896
Subject
GRB 061201: VLT optical decay
Event
Date
2006-12-03T22:58:20Z (19 years ago)
From
Paolo D'Avanzo at INAF-OAB <paolo.davanzo@brera.inaf.it>
P. D'Avanzo (INAF-OABr & Univ. Insubria) and S. Piranomonte (INAF-OAR)
report on behalf of the MISTICI collaboration:
We continued monitoring the afterglow of the short GRB061201 (Marshall
et al., GCN 5881) with the VLT equipped with the FORS2 camera.
Observations were carried out in the I filter. From a comparison with a
set of nearby field stars we conclude that the object detected in our
previous images (D'Avanzo et al. GCN 5884; see also Holland et al. GCN
5883) faded in the I-band by about 1.8 mag between Dec 2.025 UT and Dec
3.045 UT (0.359 and 1.379 days after the burst, respectively). The
inferred decay index is thus ~ 1.2.
We note a discrepancy of about 0.7 mag in the absolute calibration
during the two nights, based on observations of Landolt standard fields.
We thus warn that the absolute calibration is still preliminary. The
decay slope is however independent of this and thus robust.
We thus fully confirm that the object proposed by Holland et al. (GCN
5883) and D'Avanzo et al. (GCN 5884) is the optical afterglow of GRB 061201,
as already found by Haislip et al. (GCN 5895).
We thank the support of the ESO staff.
This message can be cited.
[GCN OPS NOTE(03dec06): Per author's request, the missing phrase
"is the optical afterglow of GRB 061201" was added to the 3rd paragraph.]