TITLE:   GCN CIRCULAR
NUMBER:  22663
SUBJECT: GRB 180418A:  Imaging of the optical afterglow with the 1.3 m DFOT and 3.6 m DOT in ARIES, India
DATE:    18/04/19 10:24:49 GMT
FROM:    Kuntal Misra at ARIES,India  <kuntal@aries.res.in>

Kuntal Misra, Abhishek Paswan, Mridweeka Singh, S. B. Pandey, T. S. Kumar, Amitesh Omar (ARIES, Nainital, India) report

We observed the field of GRB 180418A (D’Elia et al. GCN 22646) with the facilities at the Devasthal Observatory, operated by ARIES India,   located in the Central Himalayan region.  Observations were triggered around 2018-04-18T14:41 UT (nearly 8 hours after the burst) with the 1.3 m Devasthal Fast Optical Telescope (DFOT) in r and i bands and with the newly commissioned 3.6 m Devasthal Optical Telescope (DOT) in griz bands.  The afterglow is not detected in co-added images in r and i bands of 3x300 sec each taken with DFOT.  However,  we detect a faint source consistent with the position of the optical afterglow (Zheng et al. GCN 22647, Guidorzi et al. GCN 22648, Troja et al. GCN 22652, Fong et al. GCN 22659, Malesani et al. 22660) at a magnitude of 22.3+/-0.1 in r band with the ARIES Devasthal Faint Object Spectrograph Camera (ADFOSC) mounted on the 3.6 m DOT.    The magnitudes are calibrated with respect to the nearby stars and are not corrected for Galactic extinction. 

Further analysis is in progress and more observations are planned to get deeper images.

We thank the DOT operation team for successfully conducting the observations.