The mx, y, z is fairly simple to determine from the Galaxy Map grid in game. x is "trailing" ie positive x figures go towards the "east" or against the direction of spin where Sol is(so negative x numbers go in the direction of the galaxy's rotation at Sol), y is Galactic North (positive) and Galactic South (negative) as in conventional astronomy, and z is positive towards the core from Sol and negative towards the rim from Sol.
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You need some trigonometry using the distance to get the x, y, z location, which is what I made the spreadsheet for. I was just answering the point about the difficulty of converting equatorial coordinates to galactic (you need to know the star catalogue's epoch as well for which you're using coordinates, though these days unless stated otherwise it is usually J2000). The one annoyance with doing the trig on Excel is having to convert to radians rather than degrees but once I'd figured out the sine disambiguation (using the wonderful "Practical Astronomy with your calculator or spreadsheet" book, an update of one I first used in the 1990s for similar purposes) I got a sheet which will work for any star, I just plug in the Galactic Coordinates from the java tool and the distance from (say) SIMBAD and it tells me exactly where on the galaxy map any star should be. I also made a formula to work out where the star would be in the future using the x, y, z that ARICNS gives for space velocity (proper motion, etc) as stars move relative to each other over time. Not everyone's idea of fun but I loved it!
