[vsnet-grb-info 2953] GRB 060218: optical/nIR observations at La Palma

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4790
SUBJECT: GRB 060218: optical/nIR observations at La Palma
DATE:    06/02/20 01:59:46 GMT
FROM:    Alberto Castro-Tirado at Inst.de Astro. de Andalucia  <ajct at iaa.es>

A. de Ugarte Postigo, A. J. Castro-Tirado,
S. B. Pandey (IAA-CSIC, Granada), D. Barrado-
Navascués, B. Montesinos (LAEFF-INTA, Madrid),
K. Mishra (ARIES, Nainital),and S. Dehaes
(Inst. voor Sterrenkunde, K.U. Leuven), on
behalf of a larger collaboration report:

"Following the detection by SWIFT of "GRB" 060218
(Cusumano et al. GCN Circ. 4770, Gehrels et al.
GCN Circ. 4787) we have obtained UBVRIJHK images
with the 1.2m Mercator (+MEROPE) and 3.5m TNG (+NICS)
telescopes at La Palma (Canary Islands), starting on
Feb 19.85 UT (i.e. 40.8 hr after the event).
We detect a near-IR counterpart to the hard energy
source on a stacked 150s image in the K'-band with
K about 17 (with respect to 2MASS catalogue).
Astrometry against USNO-A2.0 yields RA(2000) =
03 21 39.71, Dec(2000) = +16 52 02.1 (+/-0.5").
This position is fully consistent with the optical
counterpart proposed by Cusumano et al. (op. cit.)
and Marshall et al. (GCN Circ. 4779) and with the
faint object reported by Mirabal (GCN Circ. 4783)
on the SDSS archival data (Cool et al. GCN Circ.
4777). However, we do not find evidence of underlying
extended emission in our K'-band frame (0".7 seeing).
Together with the fact that the colour index of the
source is J-K = 0, unlike GRB afterglow colours
(see fig. 2 of Gorosabel et al. 2002, A&A 384, 11),
it clearly favours a high-energy transient in our
Galaxy."

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