[vsnet-grb-info 20728] GRB 180620A iTelescope observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22826
SUBJECT: GRB 180620A iTelescope observation
DATE:    18/06/23 09:36:13 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto at phys.aoyama.ac.jp>

M. Nakamura, T. Sakamoto (AGU)

We observed the field of GRB 180620A detected by Swift
(Evans et al., GCN Circ. 22798) with the iTelescope.Net
(http://www.itelescope.net) T11 (Planewave 20") telescope
located at the New Mexico Skies Observatory (NM, USA).
20 images of 60 sec exposures were taken in the R filter
starting from June 20 on 10:11:01 (UT) about 1.6 hours after
the trigger and stopped on 10:44:55 (UT).  Due to the tracking
issue of the telescope, we only obtained nine good quality images.

We do not detect the optical afterglow both in the individual
images and the stacked image at the UVOT position
(Evans et al., GCN Circ. 22798).  The estimated five sigma
upper limit of the combined image (total exposure of 540 sec)
is ~18.1 using the USNO-B1 catalog.