[vsnet-grb-info 3771] GRB 060923A: Gemini Second Epoch and Afterglow Confirmation

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5605
SUBJECT: GRB 060923A:  Gemini Second Epoch and Afterglow Confirmation
DATE:    06/09/24 22:34:47 GMT
FROM:    Derek Fox at PSU  <dfox at astro.psu.edu>

D.B. Fox (Penn State) reports on behalf of a larger collaboration:

"We have imaged the Swift XRT localization region for GRB060923A
(Stamatikos et al., GCN 5583) with Gemini-North + NIRI on a second
occasion.  The candidate afterglow of Tanvir et al. (GCN 5587) and Fox
et al. (GCN 5597) is no longer detected, and we estimate its
brightness as:

   K-band:  Ks>21.5 mag at 05:05 UT, 24 Sep (mean epoch)

using the same photometric calibration as for the previous night (GCN
5597).  Fading of the candidate by >~1 mag between our two epochs is
separately confirmed in an image subtraction analysis.

This confirms the afterglow nature of the source, and thus the highly
reddened, high-redshift and/or highly-extinguished nature of the
afterglow of GRB 060923A."