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Subject: Re[2]: align by tripod handwheel
From: LAVANHOE
Reply To: mapug@shore.net
Date: Mon Dec 12 01:18:40 1994

Hi, this looks impressive. I've got quite some problems with my 8" LX200 in terms of guiding precision. I use the scope at f/6.3 and had expected to be able to make track-and-accumulate images with my ST-6 of x times 1 minute or so. Seldom is the scope able to deliver 1 minute exposures without tracking errors. I tried the periodic error correction but failed, though I guided manually as careful as I could and afterwards tried with an ST-4. I had the impression the situation was even worse afterwards. What I'm doing now (still looking for a better situation) is guiding with an ST-4 on a separate 2.4" guiding scope. However, although the declination shift is very small, kind of an oscillation in declination starts, resulting eventually in guiding errors. Therefore I make T&A images of n times 2 minutes with the declination correction disabled. My question, however, is : are there people out there having experience with CCD imaging who were able to fine-tune the drive to allow minute-long exposure times ? Thanks in advance Luc Vanhoeck

______________________________ Reply Separator _________________________________ Subject: re: align by tripod handwheel Author: jtws@dalsol.rtc.sc.ti.com.rtc.sc.ti.com (Ware-Dallas) at INTERNET Date: 09/12/94 9:02

> sacrilegious and scurrilous. Can't you just SYNC on the random GOTO star and
> thereby avoid damnation?
> Rob P. (not F., for pete's sake)
I think in both cases you need to be perfectly level and have exact site and time/date information. Along the lines of alignment......How many people out there have put a cross-hair on the scope and measured how accurate the tracking is in alt/az? I know most of the disscusion has been about pointing acuarracy. With the 16" I have seen a *slight* drift. This is only about an 1-2 arc seconds per minute, but it is consistant. Still pretty impressive considering it took me about an hour of polar aligning and drifting-in to get to that level of accuracy with equitoral mounts. Jason Ware