Sadly there is no longer an AstroNavgation plugin for OpenCPN as the development has stopped. There is a gpx tool around for Windows but nothing that can be used for Linux
. So a while ago I wrote my own simple gpx generator
for plotting position lines, by creating "routes".
This illustrates a round of star sights taken from John Letchers excellent old book: Self Contained Celestial Navigation
with H.O. 208. (now out of print).
./astrolop_0.1.0.rb Version:0.1.0 110320
./astrolop_0.1.0.rb lat long azimuth intercept body [1/2 length of LOP default = 10 M]
lat & long is the reference position used to produce the intercept and azimuth.
Normally this is an 'Assumed Position' to fit the tables used.
It could also be the DR position if you use H.O 211 or a calculator.
Use the last argument if the position lines are to short to produce a fix.
The script produces a gpx file named after the body ('body'.gpx).
Import this into OpenCPN wih the Route Manager.