Some Notes: 

* At ATH, 38MHz riometer was installed for 120925-161025, though the sensitivity 
  was not sufficient to see CNA.

* For Istok, GPS synchronization seems to be failed.  It was found on
March 5, 2019.  The PC clock of the VLF and riometer is less than 1 minute
different from correct time.  This error was corrected at 06 UT on March 5, 2019.
This error may be caused at the power failure on September 20, 2018. 

ISEE Riometer Home Page .