NavList:

Ah, interesting! It's a manual for one of those celestial trainers that worked like a planetarium but with collimated star images so they could be observed properly with actual sextants in one small area under the dome. 

For those of you in southern New England, two days ago I visited a really fantastic planetarium. It's the "Discovery Science Center & Planetarium", one mile off the Merritt Parkway in northern Bridgeport, Connecticut (https://www.shudiscovery.org/) which is now owned by, and was recently completely renovated by, Sacred Heart University just up the road. They have a new Evans and Sunderland digital planetarium system with 4k laser projectors which produce pinpoint star images on a deep black sky. It's amazing. The simulation is beautiful, and it has been carefully fine-tuned by the planetarium director, Elliot Severn, to display one of the most realistic and beautiful skies I have ever seen in a small-dome planetarium. Just don't think about taking sextant sights in there! Like any planetarium, the sky is so close that even a few inches of variation in position of a sextant will change observed angles dramatically. Maybe in a decade or two someone will figure out how to make an optical field appear to be at "infinite" distance, and we'll have something like those old celestial trainers again...

Frank Reed

PS: Elliot Severn is also a professional photographer specializing in space launch photography, and he has some amazing wide-view, close-up videos of rocket launches at Cape Canaveral and also Wallops that he created himself and is able to project on the digital dome. Really incredible!

File: