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Re: VCO drift



OK, I could not stand it so I did the experiment.  I just took Norman's
.TM3 log file and took differences of the time stamp.  This gave a mean
of 801.0 and a sigma of 0.6 seconds.  This for a 4 Hr 40 minute run.  
This with a resolution of 1 second on the measurements, so it could
be better but not much worse.

Seems to me that this is good enough.  You will (probably) see a variation
if you just turn on the PC and start taking data, but after 15-20 minutes
the period should settle down.  This assumes that the PC lives where people
live and you do not have a HVAC system blowing on it or some such thing.

There is a problem with the lens focal length.  The VCO optimum setting
is *not* the same for the V, R and I systems.  I will pick a compromise
but I would not build the system this way again.  I will point out that
I was building a comet finding machine and did not envision making precision
photometric measurements or running with filters when I designed the
system.

Tom Droege