I am currently in the process of writing a program that generates a GURPS Space star system according to the RAW. For the final output format I intended to make plots of the orbits, thus this question came to me.
The argument of periapsis basically describes which way the pointy ends of an orbital ellipsis points (see figure below). I have found the rules for calculating the orbital eccentricity (GURPS Space p. 116), however the book makes no mention of the argument of periapsis. Have I missed something?
(Source)
I realize that there probably is a very good way to find this out using real-world astronomical know-how (which I don't possess) but I thought it would be nice if one could characterize (i.e. personalize) the star system one generates in a little more detail.