Daytime Polar Alignment III

[jpelli]

Sky & Telescope offered the following for a Daytime Polar Alignment procedure: 
'One good way is to use the Sun. Carefully level your mount with a bubble level and set the polar axis to the latitude of your site. Hang a weighted string from the mount (between the tripod legs) and lay a protractor on the ground,centered under the string. Rotate the protractor until the string’s shadow points to the Sun’s known azimuth (measured from north through east) plus 180°. Finally, swivel the mount until the polar axis stands directly above 0° on the protractor. [/B]You are now polar-aligned.'

When they say, 'swivel the mount..', do they mean move the mount in azimuth leaving the tripod leveled and stationary? How should the tripod legs be positioned? Thank you.

[Pompey Monkey]

1 hour ago, jpelli said:

When they say, 'swivel the mount..', do they mean move the mount in azimuth leaving the tripod leveled and stationary? How should the tripod legs be positioned? Thank you.

Yes, move the mount in azimuth only.

As for the tripod legs, it only matters if, as in the skywatcher mounts, there is limited movement in azimuth due to the lug that the adjustment screws push against.

[Wpit]

I expect this will only give good az alignment as imo the accuracy of most alt scales is not that fine. 

[Wpit]

Checked my notes and even though I'm at 51 degrees north, by the time I find Polaris my glued on scale for the heq5 pro showed 54 degrees.

[ecuador]

Since I am going to the eclipse, I tried a few methods of daytime alignment, esp. using a smartphone, where the main problem was that you got huge deviations if your magnetometer was close to a metal mount. In the end I could get about 1 degree accuracy with a setup that looks like this:

(cardboard proof of concept shown - works better with hard plastic or wooden dovetail)

I made a tool for my Polar Scope Align Pro iOS app that makes it very easy to align with the above setup, with the best accuracy your phone allows:

 You could also use a compass / inclinometer app - just make sure your phone gives repeatable/accurate compass readings.

If you find it interesting, you can read more on my related blog post. 

[Wpit]

That looks fab, I would use that at night to save my knees getting damp.

[ecuador]

25 minutes ago, Wpit said:

That looks fab, I would use that at night to save my knees getting damp.

 How about knee pads?

[Wpit]

I've already got bins, head torch, glasses holders. You have to draw the line somewhere:-)

[Luna-tic]

On ‎8‎/‎18‎/‎2017 at 08:15, jpelli said:

Sky & Telescope offered the following for a Daytime Polar Alignment procedure: 
'One good way is to use the Sun. Carefully level your mount with a bubble level and set the polar axis to the latitude of your site. Hang a weighted string from the mount (between the tripod legs) and lay a protractor on the ground,centered under the string. Rotate the protractor until the string’s shadow points to the Sun’s known azimuth (measured from north through east) plus 180°. Finally, swivel the mount until the polar axis stands directly above 0° on the protractor. [/B]You are now polar-aligned.'

 

Seems like using a compass, and adding/subtracting your magnetic declination (depending on location) would get you just about as close, with a lot less work. That's how I did my alignment on eclipse day, and it was plenty close enough.