Re: practicing with sextant on land
It's sunny out today so filled my bucket with water and took some shots before and after apparent noon. My calculated latitude came out within 5 km of actual. Longitude was about 50 km too far east, but I haven't interpolated between the shots to find out the exact time of meridian, I just used a shot that was closest to apparent noon.
Most of the time is waiting for the water in the bucket to settle down. I wonder if covering the bucket would introduce a refraction error of the sun going through the glass and me looking at the sun through the glass. I don't want to use motor oil a that could get messy on cleanup. I tried levelling a mirror but gave up on that, just too finicky.
I took some shots last night of the moon and venus and have some data to play with. Polaris and mars were too faint to make out in the reflection in the bucket of water though I could see them in the sky. I still need to figure out the LOP method.