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GCN Circular 29311

GRB 201221D: near-infrared observation with LBT
2021-01-17T15:18:45Z (3 years ago)
Andrea Rossi at INAF <>
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 
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