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For each spectrum, the Class Data Format expects the following
positions:
 lambda offset from reference (usually source) position,
 beta offset,
 azimuth,
 elevation
All these elements are available in the Antenna Slow table, at
a typical sampling rate of 1 Hz. Since the spectra dumps can be
produced at different time sampling (no assumption is made on the rate
or its variations), each spectrum positions are interpolated from the
Antenna table thanks to their respective Modified Julian Day
values:

(5) 
where is the spectrum MJD value, and is the MJD
value of the trace in the Antenna Slow table. is computed
thanks to a dichotomic search in the table such as:

(6) 
being the interpolation fraction between the and
trace, the positions are interpolated by:

(7) 
where and are the spectrum and antenna lambda offsets
respectively. Same formula applies for the beta, azimuth, and
elevation values.
If is found beyond the Antenna Slow table limits, the boundary
values are applied without extrapolation. However, this is not
expected to happen since such spectra should be rejected since they
are out of the ontrack range.
Next: Tsys interpolation
Up: IRAM Memo 2014? Mrtcal
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20140701