[vsnet-grb-info 27208] GRB 201221D: near-infrared observation with LBT

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29311
SUBJECT: GRB 201221D: near-infrared observation with LBT
DATE:    21/01/17 15:18:45 GMT
FROM:    Andrea Rossi at INAF  <andrea.rossi at inaf.it>

A. Rossi (INAF-OAS) reports on behalf of the CIBO collaboration:

We observed the location of the optical afterglow (Malesani et al., GCN 
29117) of the short GRB 201221D (Page et al., GCN 29112) simultaneously 
in the J and Ks bands with the LUCI near-infrared imager and 
spectrograph mounted on the Large Binocular Telescope (LBT, Mt Graham, 
AZ, USA). Observations were obtained on 2020-12-24 at the UT midtime 
11:40:00, i.e. ~2.5 days after the burst trigger, for a total of 20 min 
of exposure in each band.

Inspection of the combined J and K-band images reveals a faint, extended 
source in both filters, for which we preliminary measure J=21.7+-0.3 
(Vega system), calibrated against 2MASS field stars.

We acknowledge the excellent support from the LBTO and LBT-INAF staff, 
particularly A. Cardwell, F. Cusano, and D. Paris, in obtaining these 
observations.