Flagging off-source data

Versions 9.5.12 and later of the Field System provide information in the logs indicating when a telescope is on- and off-source. A script now exists to convert the information in the logs into a flagging file suitable for use with the AIPS task UVFLG.

Below is an example baseline from the NME, N02C1. This was a phase referencing experiment, with rapid switching between a bright source (amplitude of corr. coeff. ~ 0.025) and a relatively weak source (corr. coeff. ~ 0.004). The integration time is one second. Shown in blue are the data after the off-source flagging information from the log file has been applied. The data points shown in red are those that were flagged based on the log information. It is clear that nearly all of the erroneous data has been removed by the off-source flagging information.

Similar flagging files will be produced routinely for all user experiments from session 3 (November) 2002. The inclusion of this extra flagging information will greatly benefit observations of weak sources and the pipeline processing of experiments.