Picket fence observations

A "picket fence" observation contains more than one "spectral window" (or "SPW"). That is, not all the frequency channels in an observation are continuous; there's at least one gap somewhere.

hyperdrive does not currently support picket fence observations, but it will eventually support them properly. However, it is possible to calibrate a single SPW of a picket fence obs. with hyperdrive; e.g. MWA observation 1329828184 has 12 SPWs. If all 24 raw data files are given to hyperdrive, it will refuse to interact with the data. But, if you supply one of the SPWs, e.g. coarse channels 62 and 63, hyperdrive will calibrate and provide solutions for the provided channels, i.e.

hyperdrive di-calibrate \
    -d *ch{062,063}*.fits *.metafits \
    -s srclist_pumav3_EoR0aegean_EoR1pietro+ForA_phase1+2_TGSSgalactic.txt \
    -n 100 \
    -o hyp_sols.fits

For this example, the output contains solutions for 256 channels, and only one channel did not converge.