[vsnet-grb-info 3849] GRB 060930: near-IR afterglow candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  5682
SUBJECT: GRB 060930: near-IR afterglow candidate 
DATE:    06/10/02 10:49:55 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia  <ajct at iaa.es>

A. de Ugarte Postigo, M. Jelinek, A.J. Castro-Tirado,  
J.Gorosabel (IAA-CSIC Granada), N. Pinilla-Alonso (TNG La Palma)
J. de León Cruz (IAC Tenerife), J. Licandro (ING-IAC)

on behalf of a larger collaboration report:

We have observed the field of the GRB 060930 detected by INTEGRAL 
(Gotz et al., GCN 5665) with the 3.5m Telescopio Nazionale Galileo 
(+NICS) at La Palma in the JHK bands on 30 Sep 2006 (from 20:30 to 
20:51 UT) and revisited the field in H band on 1 Oct 2006 (from 
20:37 to 20:51 UT; i.e. 11.5 hr and 35.5 hr respectively after the 
onset of the gamma-ray event).

The NICS frames cover the central 80% of the INTEGRAL/IBIS error 
box (2.5' radius). We detect a variable, stationary object at the 
following coordinates (J2000):

RA = 20:18:11.51, Dec = -23:37:19.6

with an astrometric error of 0.5".

In the first epoch the source is detected in all 3 bands and has 
an H band magnitude of ~18.2. In the second H band epoch it has 
faded by about 1 magnitude. This would imply a decay index of 
alpha -0.9 +/- 0.2 .

For this object we obtain (Js-K)=1.10+/-0.22, consistent with the
near-IR colour expected for a GRB afterglow (Gorosabel et al. 2002, 
A&A, 384, 11).

A finding chart is available at:

http://www.iaa.es/~deugarte/GRBs/060930/grb060930.gif

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