From: Milton Aupperle <milton@outcastsoft.com>

Date: June 21, 2008 2:59:17 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Quick question about alignment

Dear Kirkus;

On 21-Jun-08, at 2:36 PM, KirkusMcGurkus wrote:

For solid, accurate tracking, how dependent is Astro IIDC on good

polar alignment of the mount?

If the mount is off a lot, then it's continually makes corrections to compensate. Dec corrections is always a major issue because of Dec motor Lag. RA Lag is less an issue, unless the gear tensions is bad and then you have "play" on the RA access.

I had one excellent night of tracking several weeks ago - I was easily

able to get 10 minute exposures with barely a hiccup. But since then,

I've had some trouble with getting my mount dead-on as far as polar

alignment. And since then, I've not been able to get Astro IIDC to

reliably track at all.

Which "version" of Astro IIDC?

And have you changed anything on your mount, like gear tensions / motors / re-balanced it etc? And has it warmed up a lot since you last had accurate tracking?

For example, my HEQ5 mount was tracking "okay" on the east side of the north south line, but as as soon as it crossed over to the west side, tracking errors was 1/4 of what it was before. I re-balanced my scopes counter weights  to give it less weight to the east and tracking improved a lot.

And now that the weather has finally warmed up here, I have to once again (third time since spring arrived) re-adjust the tension of gearing for the both RA and Dec. If I don't, I get play on the RA or DEC access when it warms up and when it cooler the gears can "Bind" when slewing at high speeds.

Add in turbulence (which gives false directional changes), over loading of the mount (which stresses the motors and reduces response time), poor weight balancing (which stresses the motors and also causes gear issues) and tracking can go form great to crap very easily.

HTH..

Milton J. Aupperle