GCN Circular 21942

S. B. Pandey (ARIES Nainital), Brajesh Kumar, G. C. Anupama (IIA Bangaluru) 
and Kuntal Misra (ARIES Nainital) on behalf of a larger GRB collaboration 


Short-duration GRB 170428A (Swift trigger =750298, Beardmore et al. GCN 21042
Not found
 
 
) 
was observed by the 3.6m Devasthal Optical Telescope (DOT) recently commissioned 
by ARIES Nainital. The observations were carried out as a part of early science 
run and characterizations. Observations were carried out just before twilight 
using the 4Kx4K CCD optical imager, the first light instrument. Several R-band 
exposures of 300-sec each were acquired in seeing conditions of around 1.1 arcsec 
starting around UT 22:45:57 i.e. 13.5 hours after the burst. 

In the stacked R-band frame of 3*300-sec, the candidate optical afterglow (Xu et al. 
GCN 21048
Not found
 
 
; Bolmer et al. GCN 21050
Not found
 
 
) was clearly seen embedded within the host galaxy. 
The photometry at the afterglow position measures a magnitude of 22.7+-0.2 mag 
(calibrated with respect to nearby USNO stars). However, in the present data-set, 
contamination with the probable host galaxy can not be ruled out in the estimated magnitude. 

This is the first GRB afterglow observations with the 3.6m DOT and the full team of 
staff members associated with the project are thankfully acknowledged to get this telescope 
commissioned. We expect to contribute towards observations of time critical events in 
near future assuming longitudinal advantage of Indian sub-continent using this facility. 

The message may be cited.