Astronavigation progs MS-DOS
It greatly simplifies the steps needed to obtain an altitude line. Once you get used to it just a little, all you have to do is input the data (time and altitude) straight from your notepad and go to the Summary to draw the lines on the chart.
This allows you, at twilight, to get really accurate fixes withoutbothering with tables and Almanac.
The T(w)ilights function, which gives altitude and azimuth of all "useful" stars at a certain time in a certain place, lets you get ready for observations in time so you can get an altitude on a lot of different stars.
Quite handy is the "summa(r)y key, which gives you a list of allobserved altitudes to easily draw the lines on the chart.
For the Sun you don't need the printed almanac, for the stars you need it only to update the star data, once a month at the most, but you need it for the planets.