Hi Paul,
My goal with this approach is to simply get a rough alignment by using the sun.
I originally came up with the idea when I was at a loss setting my rig up for
the last solar eclipse we had the-day-of and had to improvise. I've used it
every time since and it's been very reliable. I was using a compass and
magnetic declination approach previously but that is only helpful for azimuth
estimation assuming there's no iron in your mount.
Assuming you have a nearly straight tube, all you're really trying to do is
collimate the mechanical axis of the tube with the position of the sun. That
mechanical axis when placed squarely in the saddle of the mount approximates
closely where the mount is actually pointing.
You can test the idea out without a mount of course. Simply go outside on a
sunny day (do we have those anymore?) and experiment. When the tube is centered
on the sun you will see a near-perfect ring shadow from the tube. Even a slight
offset causes a thickening of the shadow one side and an "eclipsing" of the sun
projection.
Not sure if I mentioned this but this assumes that the mount is a German
equatorial type and that you can slew it to point at the sun during the day
(without any optics attached of course!).
Greg
----- Original Message -----
From: "Paul Lind" <pulind@xxxxx>
To: az-observing@xxxxxxxxxxxxx
Sent: Wednesday, March 20, 2019 7:51:21 PM
Subject: [AZ-Observing] Re: Can I blame my tools now? And daytime polar
alignment.
Greg,
I'm interested in your method of daytime polar alignment on the sun. Is the
idea to point at the sun and wait and see how well the mount tracks, and then
make adjustments to the polar axis? Can you elaborate on this? Also, Ken Naif
has an interesting method of determining true north from shadows of the sun We
found that it works well, but it requires preparing a table of sun positions vs
time ahead of time.
Paul Lind
----- Original Message -----
From: Greg Schwimer <schwim@xxxxxxxxxxx>
To: az-observing@xxxxxxxxxxxxx
Sent: Wed, 20 Mar 2019 20:51:02 -0400 (EDT)
Subject: [AZ-Observing] Re: Can I blame my tools now?
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