[AAVSO-HEN] GRB041006: VLT observations of the afterglow and host galaxy

[grb at aavso.org]

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TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2803
SUBJECT: GRB041006: VLT observations of the afterglow and host galaxy
DATE:    04/10/14 11:16:39 GMT
FROM:    Daniele Malesani at SISSA-ISAS,Trieste,Italy  <malesani at sissa.it>

S. Covino, D. Malesani, G. Tagliaferri, P. D'Avanzo, L.A. Antonelli, G. Chincarini, M. Della Valle, F. Fiore, D. Fugazza, L. Stella, on behalf of the MISTICI collaboration, report:

We observed the optical afterglow (Da Costa, Noel & Price, GCN 2765; Maeno et al. GCN 2772) of GRB 041006 (Galassi et al., GCN 2770) with the 8.2m ESO-VLT-UT2 (Kueyen) at Cerro Paranal. Observations were carried out under good observing conditions (seeing 0.9") with the FORS1 instrument.

The afterglow is clearly detected in the B, R and I bands. We report the following magnitude for the object (calculate performing PSF photometry):

  R = 23.59 +- 0.06 on 2004 Oct 11.121 UT

The decay seem therefore even steeper than that inferred from the previous TNG observations (Fugazza et al., GCN 2782; D'Avanzo et al., GCN 2788).

In our coadded images, we also detect an extended emission surrounding the afterglow, apparently 2.5" in size (18 kpc at z=0.712; Fugazza et al., GCN 2782; Price et al., GCN 2791). As suggested by Fynbo et al. (GCN 2802), this is likely the host galaxy of GRB 041006. Performing PSF photometry, we estimate that the contribution inside the afterglow PSF area is likely very small. The afterglow is located inside the galaxy, about 1" South West of its nucleus.

A snapshot centered about the GRB position is posted online at the following URL:

http://www.sissa.it/~malesani/GRB/041006

together with an updated light curve with all public data.

We acknowledge the excellent support from the observing staff at Paranal.


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