We have written a CLASS procedure called "calib_evol.class" that allows us to follow the time evolution of some calibration results throughout an observing session for a certain project, day, and EMIR subband. For example, it may help us in exploring the Tsys dependence with the antenna elevation, or the variation along the day of the estimated amount of water vapor.
We should connect to operator@mrt-lx3, and go to the directory:
Once there, we execute CLASS and load the procedure with the following parameters:
LAS> @calib_evol xxx-yy backend subband date first_scan last_scan
xxx-yy: project name (e.g. 120-19).
backend: backend name, in upper case (FTS, WILMA, VESPA, BBC, NBC).
subband: EMIR band, polarization, and subband (e.g. E1HLI).
date : date of the observation in the format yyyymmdd (e.g. 20200717). A 0 means to take the current date.
first/last scan: scan range to plot. 0 means to start or finish with the first or, respectively, last scan.
For example, the procedure call below...
LAS> @calib_evol 120-19 FTS E1HLI 20200105 106 0
... will generate the following graph, where for each scan number we plot:
- Lower panel: Values of the system temperature (Tsys) and the antenna elevation; Under perfect, stable weather, their variations should anticorrelate.
- Upper panel: Zenith opacity (Tau zenith) and the amount of water vapor (pwv); Their evolution should correlate.
The frequency in the header corresponds to the rest frequency of the central channel.
Note: The origin of this procedure was to investigate possible interferences that increased abruptly Tsys (see 5-Jan-2020 operator reports).