NavList:

Al Soto, you wrote:
" Is there not a method to calculate position at night by shooting the angle(s) between 2 or more stars without needing the horizon?"

How about two stars and the Moon?

For a fix without a horizon in the middle of the night, you shoot a pair of lunars in roughly perpendicular directions from the Moon at known GMT (distinct form traditional lunars which were shot specifically to find GMT). Each shot places you on a three-dimensional "cone" of position with its apex at the center of the Moon, as I outlined originally back in 2006. This cone extends out into space and crosses the Earth's surface. Except for very short angles, this cone of position cuts the Earth's surface in a nearly straight line as seen from the Moon. On the surface of the Earth it's a rather complicated curve, but it can be solved if necessary. This isn't something that you would ever find useful on a small boat since the accuracy of the fix demands very high accuracy in the measured lunar arcs. If you can get your lunars accurate to +/-0.1' (which requires averaging multiple sights in addition to doing everything else exactly right), then your fix is accurate to +/-6 nautical miles --and that's when the geometry is favorable.

A fix by lunar distances is clearly not much use down here on the surface of the Earth, but it was considered a potentially useful autonomous form of navigation for flying in deep space fifty years ago, and that's why the Apollo spacecraft had a fancy sextant built right into its pressure hull. In the end, they didn't need the sextant for this position-fixing role, but it still served a vital purpose as an astro-compass, resetting the orientation of the inertial navigation system every day. It also served as fine computer-driven telescope for observing any chosen point on the surface of the Moon, and in this role it allowed the orbiting astronaut in the Apollo command module to spot the lunar module (and astronauts) on the ground below.

Frank Reed