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Finder charts are of no use with either an inexperienced observer or an
automated telescope.
Bruce
J. Forster wrote:
My girl friend is a regular observer (w/ a PhD) at the Smithsonian
Astrophysical Observatory and uses the instruments at Mt. Hopkins all the
time. I KNOW what she does. Their finder charts got to better than 20th
magnitude, NOT just bright objects.
-John
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J. Forster wrote:
J. Forster wrote:
The two big ones I remember are:
A Boller& Chivens 24" about 1 degree
Only with a camera, not with an eyepiece.
True, but telescopes have guide scopes with much shorter focal lengths,
typically 1 vs 9 meters.
It isnt always possible to find an operator who has the time or
expertise to use a guide scope together with a finder chart properly.
This restricts them to bright objects like the moon Jupiter, Saturn etc.
Locating Uranus, Neptune etc is out of the question.
If the object of interest is too faint to see in the guide scope then
accurate pointing is essential.
The technique of offsetting from a visible object in the guide scope or
finder scope isn't easy to learn.
An automated telescope needs to have accurate pointing to acquire the
object of interest.
When one is using an instrument (e.g. spectrograph, photometer) with a
narrow field of view the pointing accuracy becomes critical to reduce
the search time required to acquire the object of interest.
Eyepiece field of view is something like 20 arc minutes with a 2"
eyepiece.
A 60" about 15 arc-minutes
The MMT is about 1 degree, I think.
No one uses an eyepiece with the MMT (something of a misnomer now that
it uses a single primary mirror).
The quoted FOV is for a camera only
-John
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Bruce
Bruce
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