GCN Circular 4583
Subject
GRB 060116: Further analysis of VLT photometry and optical spectroscopy
Event
Date
2006-01-24T21:45:37Z (19 years ago)
From
Daniele Malesani at SISSA-ISAS,Trieste,Italy <malesani@sissa.it>
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S. Piranomonte, V. D'Elia, P. D'Avanzo, D. Malesani, A. Grazian, D.
Fugazza, L.A. Antonelli, S. Campana, G. Chincarini, S. Covino, M. Della
Valle, A. Fernandez-Soto, F. Fiore, L. Stella, G. Tagliaferri, and V.
Testa, report on behalf of the MISTICI collaboration:
"We have performed a more detailed analysis of our optical/NIR
photometry (D'Avanzo et al., GCN 4532; Malesani et al., GCN 4541;
Grazian et al. GCN 4545) of the afterglow of GRB 060116 (Campana et al.,
GCN 4519, 4522; Kocevski et al., GCN 4528, 4540).
We compared the available photometry with a power law afterglow,
including rest frame dust extinction. The chi square versus z curve
presents two minima. The lowest chi square corresponds to the solution
with z~6.6 and little rest-frame extinction as reported in GCN 4545. The
other minimum corresponds to a solution with z=3.8-4.5 (1 sigma
confidence level) and E(B-V)~0.5.
On 2005 January 19, starting at 01:19 UT (about 2.7 days after the GRB),
we obtained low resolution spectra of the afterglow of GRB 060116
(Kocevski et al. GCNs 4528, 4540) using VLT+FORS2. The observation
consisted of 10 exposures of 1800 seconds each using the grism 300I with
a 1" slit under good seeing conditions. A very faint object, close to
the detection limit, is visible at the afterglow position in the
combined spectrum. Its spectrum may extend down to about 7000 Angstrom
blueward. This would be consistent with the lower redshift reported
above. However, the statistics is very poor and a robust conclusion can
not be drawn at this time. Further analysis is in progress.
We acknowledge the efficient support of the ESO staff at Paranal.
This message can be cited."