TITLE:   GCN CIRCULAR
NUMBER:  21159
SUBJECT: LIGO/Virgo G268556: BSA radio observations at 110 MHz
DATE:    17/05/28 19:00:29 GMT
FROM:    Alexei Pozanenko at IKI,Moscow  <grbgw.iki@gmail.com>

A.S. Pozanenko (IKI), V.A. Samodurov (HSE, PRAO LPI), M.O. Toropov (JSC 
Business Automation), A.E. Rodin (PRAO LPI), P.Yu. Minaev (IKI), S.V. 
Logvinenko (PRAO LPI), V.V. Oreshko (PRAO LPI) report  on behalf of 
IKI-GW follow-up collaboration:

We have investigated daily data survey of BSA radiotelescope operated at 
109.0-111.5 MHz in a survey mode (Samodurov, et al. 2015, 
http://adsabs.harvard.edu/abs/2015OAP....28..242S). At the time of 
trigger of G268556 (LIGO Scientific Collaboration, GCN 20364) the 
diagram of BSA was 10:39 hours after and 13:21 hours before passing of 
the localization area of G268556 between Dec=+15.0 deg and Dec=+42.0 deg 
(i.e. most sensitive part of the BSA diagram). We do not detect any 
source brighter than 3 Jy  (exposure of 300 s) on (UT) 2017-01-04 
23:33:00, i.e. 13:21 hours after  the G268556  trigger in Declination 
range between +15.0 and  +42.0 degrees.  We used previous passages of 
the localization region through the diagram to estimate possible 
variability of the flux and to estimate the upper limit. Result reported 
is preliminary and might be refined.