Re: (IAAC) Obj: S518 - Inst: 6" TEC Mak, f12, GP

Bill Becker wrote:
>I was using the data(for sep & pa) from The Night Sky Observer's Guide.
>I do have a micrometer ocular but the mounts I'm currently using don't
>have drives so making accurate measurements is a bit tough.

I "eyeball" angular sizes of objects based on field size.  With this method,
for me anyway, it becomes more and more difficult to  even get in the
"ballpark" as smaller and smaller objects are viewed.  It occurred to me
recently that it should be possible to estimate sizes by timing the drift of
the object off the edge of the field.  The conversion of time to distance
would vary by declination and, btw, would seem to be more difficult and time
consuming the further the object is from the celestial equator.

Has anyone attempted this?  Is it at all practical?  Does anyone know if
conversion formulas are available?  Does any of this make any kind of sense?
Bill's statement seems to imply that it might be possible.  But I don't
understand what a drive has to do with it.  It seems as though you would
turn off the drive to do the measurement.

Any insights would be appreciated.

Don Clouse

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