Ken, Orrery is great I have loved since my neo1973, obviously a labor of love. I especially like the almanac for celestial navigation.
I have wondered if you a could create an input to let the math run backwards and enter object elevations over time with averaging in order to establish a steadily moving or stationary location and/or time. I am hoping to ferry a single engine plane across the north Atlantic as a working holiday (Canada ,Greenland, Iceland, Ireland, UK) maybe even next year and while GPS will be on board along with other nav instruments there is something historic and great about celestial navigation(nautical sextant with bubble horizon) even if I use my phone to cheat on calculations. If I have to do the paperwork by hand I will likely not be able to do celestial nav as I will have other jobs while airborne.
Also for geeky fun lunar distance tables and even even better input lunar distance from sextant to bootstrap exact time(and option to send this to the phones time setting).
Lastly if you choose to add the sextant nav input why not let that info be sent to a fake gpsd server and let us display it on a map with CEP.
I understand that this stack of requests takes the app away from stars and turns it into a mapping app(split?), this would be a novel even unique app that I feel would be appreciated by those of us who love practical celestial navigation but don't want or simply can't always to do the math in real time.
Lastly as I already have the genie lamp in hand, any thoughts on porting to Ubuntu or another desktop OS so we can see the best sky watching program on a big screen or projected onto a wall?