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Astronomy/Celestial coordinates

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Expert: - 12/30/2011


Question
Dear Mr. Whiting:

Regarding the celestial coordinate system is it correct to say that the declination always stays the same whereas the righ ascention changes throughout the evening when observing? can one set an eq mounted scope to the correct declination and then swing the scope to where the right ascension should be (providing that the scope is properly aligned to the north celestial pole)?

Thanks

Randy

Answer
Hi Randy,
Yes, the (North-South) declination value will remain nearly constant (see below) AS LONG AS you only move the scope in the Right Ascension mode (East West) and don't change the altitude position of the scope.  In practice however, if you (the polar axis) aren't EXACTLY on the North Celestial Pole, then as time goes by, tracking across the sky, you'll get some slight "declination drift" (in the eyepiece of the object being observed) and you'll have to adjust the declination value (knob)... accordingly, just a little, every so often.
In major observatories with computerized equipment, this is generally not a problem because
even before any declination drift occurs, the computer senses the tiny change, and will correct for it... even before it happens!  (So their pictures always come out... in sharp focus and relief, with excellent tracking... even if they track on one object, all night long!)
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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