[vsnet-grb-info 19757] GRB 170830A: iTelescope optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21764
SUBJECT: GRB 170830A: iTelescope optical observations
DATE:    17/08/30 09:48:50 GMT
FROM:    Denis Denisenko at SAI MSU  <d.v.denisenko at gmail.com>

D. Denisenko (Sternberg Astronomical Institute, Moscow State
University) reports:

MAXI/GSC error box of GRB 170830A (T. Yoneyama et al., GCN 21761) was
observed remotely by iTelescope.Net T32 instrument (0.43-m f/6.8
reflector + FLI Proline 16803 CCD) in Siding Spring, Australia, at
08:55-08:58 UT on 2017 Aug. 30 (5.7 hours after the trigger time). The
telescope was centered at R.A. = 17 48 20, Decl. = -01 50 00 with a
43'x43' field of view covering the entire rectangular error box by
MAXI/GSC. Observations were performed at the zenith distance of 31
degree, only 18 deg from the waxing Moon (phase 0.60).

Visual inspection of the combined image (3x60-sec unfiltered
exposures) against 1991-06-15 DSS Red plate shows no optical transient
to the 3-sigma upper limit of 18.5m (calibrated against USNO-B1.0 Red
magnitudes). In particular, there is no new object in the vicinity of
the unidentified ROSAT X-ray source 1RXS J174835.3-014843 which falls
inside the gamma-ray burst error box.