NOTES:

Each set of two beams (assigned as a single job to 2 CPUs on a node)
typically takes about 10 hr of wall time to process. This is for a 2.3
min observation, which produces two raw files to be appended. A 4.5
min observation (which produces three raw files to be appended), takes
roughly 18 hr of wall time.

The maximum (but seems to be stable) sustained data download rate from
the Cornell data portal with FOUR simultaneous streams is 1.2 MB/s
(9.6 Mbit/s), or about 100 GB/day.  The network setting is 125 KB/s (1
Mbit/s) guaranteed.

We are checking all candidates down to presto_sigma = 7.5 in the
GUI. This seems to account for all of the viable candidates and there
are just too many weaker ones below this to peruse.

Empirical tests indicate that candidates with prepfold S/N < 6 are not real, 
so only consider those larger than 6.0.