TITLE:   GCN CIRCULAR
NUMBER:  21618
SUBJECT: LIGO/Virgo G298048: optical observations of CHILESCOPE observatory
DATE:    17/08/20 14:24:47 GMT
FROM:    Alexei Pozanenko at IKI,Moscow  <grbgw.iki@gmail.com>

A. Pozanenko (IKI), E. Mazaeva (IKI), A. Volnova (IKI),  P. Minaev 
(IKI), M. Krugov (AFIF) report on behalf of IKI-GW follow-up collaboration:

We observed  the field of  LIGO/Virgo trigger G298048 (LVC GCNs 21509, 
21513) and the error circle of GMB/Fermi short burst GRB 170817A 
(Connaughton et al., GCN 21506) with RC-1000 and ASA-500 telescopes of 
CHILESCOPE observatory located at W 70d 34m S20d 27m. The observations 
started on Aug 17 (UT) 23:17:16 in clear filter. The last image was 
recorded on 2017-08-18T00:59:48.

We cover central part of G298048 localization with typical limiting 
magnitude of 20m at 60 s exposure in each image. The covering map can be 
found in
http://grb.rssi.ru/GRB170817A/bayestar_RC1000%20coverage.png

The OT candidate found by Coulter et al. (LVC GCN 21529), the DLT17ck 
(Sheng Yang et al., GCN 21531) is out of the coverage in the first epoch 
of the observations.

We also cover northern part of GBM/Fermi  localization?  1-sigma 
containment, statistical only (Connaughton et al., GCN 21506). The 
coverage of the GBM localization is about 20%. Typical limiting 
magnitude of 17.5m at 60 s exposure in each image. The covering map can 
be found in
http://grb.rssi.ru/GRB170817A/GRB170817A_GBM_coverage_ASA500.png

The detailed investigation of the fields is underway.

We are grateful to the remote staff of the observatory for timely 
observations.