Polar alignment, Star alignment
All affected by the Meade ETX Telescopes, Meade Autostar and tripod
How Precise Can the Meade ETX Autostar Observation System Be?
The Meade Autostar is designed to compensate for a lot of user errors.
If your time, location, and alignment (Polar alignment, star alignment)
are not exact, the tracking will not be correct and the GOTO will
be inaccurate. The field of view of a 26 mm eyepiece on the Meade
ETX-90 is about one degree. The straight viewfinder 8 x 21 mm has
a field of view of 6.8° straight or 6.4° for the right-angle
viewfinder. It is possible to have the star appear in the eyepiece
90% of time on GOTOs with a precisely completed setup. For a less
precise setup, the star may not appear in the viewfinder. It might
appear just outside the viewfinder's view.
What Affects the Meade ETX Autostar Observation System?
The perfect result of a process is the precise completion of all
of the steps that lead to the result. The more precise each step
is, the more precise the end result will be. Every little error
introduced at each step of the process results in larger error at
the end. A precision result can only be achieved if all of the steps
are completed with precision. For example, entering the exact Altitude
and Longitude of your house instead of choosing the closest city
in the Autostar would introduce less error. The closest city could
be many miles away. Entering the exact time read from an atomic
clock instead of the time from the microwave oven would introduce
less error. The time on the microwave oven might be inaccurate.
A tripod that is not perfectly level would cause the Azimuth movement
(horizontal turning) to not be fully horizontal. This inaccuracy
could also cause the Altitude movement (vertical) to not be plumb.
Your polar alignment and star alignment therefore would not be precise.
The Meade Autostar also compensates for a degree of free-play on
the motor and drive gear system. There are settings for the degree
of telescope drive system free-play. These settings must be precise
as well in order for polar alignment and star alignment to be accurate.
What Gives You Consistency?
There will be no consistency without precision steps. All of the
stars are many light-years away. Therefore, a small error here,
a little inaccuracy there, and things start to add up to create
significant problems. If setup properly, the Meade ETX Autostar
telescope is amazingly precise even at such a low cost.
There are no overall instructions for the beginner. There is a manual
for the telescope on how to use the telescope. There is also the
manual on how to setup the Autostar. There may be a manual for the
tripod. These manuals are not integrated. They deal with each piece
of equipment individually without any integration between them.
It is important that each piece work with the other pieces.
The Goal
My experience is that, with a proper and precise setup and alignment
(polar alignment and star alignment), you can expect better that
80% of your GOTO targets will appear (not necessarily centered)
in the 26mm eyepiece of the Meade ETX-90EC. All target stars will
appear in the viewfinder. A somewhat less precision alignment, will
have all the target stars appear in the viewfinder but not necessarily
in the eyepiece. If you follow the instructions here, you will get
good GOTO accuracy and night-after-night consistency
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