Calibration loads

The loads of a calibration scan can be displayed in a plot with e.g. the command:

MRTCAL> @ plot-loads iram30m-4mhz-20100930s200-imb.fits

The result is shown in the Figure . It shows the load values as found in the DATA column of each subscan. They can be averaged (i.e. display a single average load) or not (i.e. display all the single dumps) thanks to the option /AVERAGE YES|NO (default is YES). Under normal conditions, we expect the load intensities to arrange in the order Cold $<$ Sky $<$ Hot for a proper calibration.

Figure: Resulting plot of the procedure @ plot-loads. X axis is the output of the backend, i.e. a collection of backend “parts” (e.g. E0HLI, E0VLI, and so on) glued together; they need to be split and reassembled in the correct order to produce spectra with sky frequencies. It displays i) the 3 loads Cold, Sky, and Hot, and ii) vertical grey lines showing the range of channels to be used; outer channels are discarded (none here). The mean load value per chunk is also displayed in black, overlaid to each chunk load curve.

Figure: Same as Fig. , but this calibration scan has incorrect loads (note the E0VLO backend part in the center with Hot $<$ Sky $<$ Cold).