Re: How often do you need to polar align a permanent mount?
toggle quoted messageShow quoted text
I had a concrete pier with eight foot footings. Polar alignment changed due to ground shifting (finally settled after about a year) and concrete differential shrinkage (continued for about four years).
The concrete shrinkage was the same effect observed in many observatories-including the Hale 200”.
From: firstname.lastname@example.org <email@example.com> On Behalf Of Peter Bresler via groups.io
Sent: Wednesday, November 4, 2020 11:58 AM
Subject: Re: [ap-gto] How often do you need to polar align a permanent mount?
I have my 1200 on a concrete pier with 2 foot footings, rebar. Polar alignment periodically changes for reasons I am not sure off...it even could be small earth quakes here. I use Sharpcap Pro to polar align. I can tell its off when stars start moving with longer exposures. I probably need to adjust every few weeks.