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    Correct the spectrum for elevation gain losses as a function of frequen-
    cy and elevation. This is valid for point sources. For extended sources,
    the correction is less, depending on the size of the source.

    The rest frequency and elevation are taken from the spectrum header, as-
    suming that the gain stays constant over  the  entire  bandpass  of  the

    This  correction  is only implemented for 30M data. The formulae for the
    gains are documented in Juan Penalver memo 16-Apr-2012. The gain is  the
    ratio of aperture efficiency at the elevation of the observation, divid-
    ed by the maximum aperture efficiency near 50 degrees.

Gildas manager 2020-04-07