GCN Circular 29645

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

We observed the field of GRB 210306A (D'Elia et al., GCN 29597
Not found
 
 
) 
simultaneously in the r' and z' bands with the LBC imager mounted on LBT 
(Mt Graham, AZ, USA). We obtained 20min of imaging on 2021-03-11, 5.06 
days after the burst trigger. Observations were performed under good 
weather conditions with an average seeing of ~1.2".

We clearly detect the afterglow and we preliminary measure

r=24.2+-0.2 (AB system),

calibrated against SDSS field stars. This is still in agreement with the 
late decay index alpha~1.1 (after an initial plateau ending at ~2hours 
after the burst trigger) obtained modelling the photometry available 
(Strausbaugh et al., GCN29600
Not found
 
 
; Zhu et al., GCN 29607
Not found
 
 
; Hentunen & 
Nissinen GCN 29603
Not found
 
 
; Hosokawa et al., GCN29608
Not found
 
 
; Dimple et al., GCN 29618
Not found
 
 
; 
Belkin et al., GCN 29616
Not found
 
 
, GCN 29620
Not found
 
 
, 29635
Not found
 
 
; Klose et al., GCN 29644
Not found
 
 
).

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