RE: [APML] drift alignment

["John C. Mirtle" <mirtle.j@home.com>]

Bobby;
	This whole up/west/down/east thing is really confusing. Here's the simple
run-down.

Azimuth - using a star transiting at 0 degrees, to the south. Watch the
drift. To correct the error, rotate the mount in azimuth so that the star
moved IN THE DIRECTION of the drift. ie: if the star moves up in dec, rotate
the mount so that it moves further up. Reset the star back to the crosshairs
by moving the scope. Rinse and repeat.

Altitude - using a star in the east or west. Watch for drift in declination.
Move the mount in altitude to BRING THE STAR BACK to the crosshairs. Repeat.

	The star will move back and forth in RA - ignore it as long as the star
doesn't move too far. What you need to monitor is declination. When I align
(which is every time I go out!) I pick a star to the east that is at least
20 degrees up. This avoids seeing effects. Hope this helps!

John Mirtle
Calgary, Ab. Canada


-----Original Message-----
From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org]On
Behalf Of ZenAstro
Sent: Sunday, September 30, 2001 11:58 PM
To: astro-photo@seds.org
Subject: Re: [APML] drift alignment


At 08:40 PM 9/30/2001 -0500, you wrote:
>I don't do this very often because I'm pier mounted. But every so often
I'll
>tweek my alignment. Question: on the eastern star drift we always use the
>terms "drift up" or "drift down" to describe the star movement. Is this
>along the RA or DEC axis? I'm getting movement along both axis and assume
>it's atmospheric induced or something. My drift on the meridian star is
>great; none for 15 min after refinement of my mount.



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