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Astronomy/RA tracking using drive motor

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Expert: - 3/1/2008


Question
I have a F8 Catadioptric Newtonian on a Equatorial mount.
The clock drive motor is an EQ3 single axis drive corrector.
All adjustments seem correct (base is level, polar axis 28.5 north with Polaris on the small circle of the reticle per star chart position). My problem is that any star/planet I track will slowly drift north with the object in the eastern sky. No mater how I tinker with the equatorial adjustment nothing has changed the drift. What is going on here? Any advice you can give me is greatly appreciated.    Alex Simon

Answer
Hi Alex,
I've never owned a motorized scope, but I have read that IF you're
getting north or south eyepiece drift, then you aren't on the exact pole, no matter how much you've checked it...it's called declination
drift, and it's caused by not being exactly on the pole with
your polar axis. And realize, Polaris is not exactly at the pole either, I believe it's currently 0.7 degree from the true pole.  So for super-accurate tracking, you have to offset that much from Polaris. (If your alignment device has a 'built-in' offset from
Polaris, then it seems to me that maybe that's what has, perhaps,  become out of alignment).
 
That's about as far as I can go, with absolutely zero experience with Equatorial mounts, clock drives, and GOTO's as I use none of these. I suggest if this information above doesn't help, please ask same question to allexpert's Paul Wagner, as he is our real expert on
telescopes themselves, and should be able to help you more.
He's built scores of scopes, whereas I buy mine and
I use strictly Dobsonian non-motorized equipment....I don't build
them whereas he does, so he knows far more than I do on this particular subject.
Hope this helps,
Clear Skies,
Tom Whiting
Erie, PA

Astronomy

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Tom Whiting

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Astronomy has been my hobby/pasttime for over 50 years.  Currently own 3 telescopes, the largest of which is a 30 inch Newtonian truss Dob that is portable.I taught Astronomy/Meteorology at the University Level for 13 years before retiring in 1995. Being retired and home most of the time, I am able to answer all questions relatively quickly, unless it's a new moon weekend with good observing conditions.  No astrology questions please, or questions about alleged UFO picture identifications.

Experience

Experience: Astronomy has been my hobby and study for over 50 years. We currently now own a 30 inch portable telescope (Updated - Pennsylvania`s largest portable telescope). It can be seen on our website at:http://www.velocity.net/~bwhiting and also attend several regional starparties during the year, and have been on 5 total solar eclipse expeditions.

Organizations: President, Erie County Mobile Observers Group for over 15 years.

Publications: Wrote the "Over Erie Skies" newspaper article in our local newspaper for 11 years (1975-86).

Education: Masters Degree- Taught at the University level for 13 years. Retired 20 years -USAF Pilot - KC-135 with 180 combat missions;  Also Eagle Scout, Philmont staff 2 Yrs, Order of Arrow Lodge Chief, Ham Radio (inactive).

Awards: two discoveries: The mini-coathanger asterism in Ursa Minor (the little dipper) And the mini-ladle- another asterism in the bowl of Ursa Minor. Clients: Currently President of the ECMOG as mentioned above.

Education/Credentials
BS  Metallurgical Engineering Grove City College, PAMaster's Degree, Gannon University, Erie, PA Also retired USAF pilot, 20 years.

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