Delay compensation DE601

Data taken between December 9, 2016 and June 6, 2017 have an extra delay of 1 micro second on baselines involving DE601. There was an extra delay manually introduced into the system due to the speciffics of its GPS unit. The unit was replaced in December, but the extra system delay for that station was not removed until June.

This can be accounted for during data reduction by fringe-fitting assuming that there was no large frequency averaging applied. For example, a frequency resolution of 4 ch/ SB is sufficient for reduction, but data averaged to 1 ch/SB will have issues.

A possible fringe fitting strategy is to subtract 1 microsecond delay from all the baselines containing DE601 and fringe fit using a delay window of around 600 nanoseconds.

The issue affects only interferometric observations using the Cobalt correlator.

Design: Kuenst.    Development: Dripl.    © 2021 ASTRON