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Atmospheric dispersion corrections are based on the variation
of the visibility phase with wavelength. In order to increase the
SNR for these data, we coherently integrate the complex visibility
for typically 200 ms. The coherent integration is done using the COBRA
procedure cohstrictor. In order to provide the necessary
input file for this step, the following CONSTRICTOR parameters should
- OutFile = YYYY-MM-DD.coh. The .coh extension is standard for
- Raw = On. Write the raw data of every scan into a separate HDS file.
These files are needed by cohstrictor to compute the
and fringe delays.
- NumAv = 100. Integrate 100 2ms samples. This seems to be a good trade-off
between SNR and possible systematic error at longer integration times.
- Metrology = On. Pass on metrology data