Hello All, Noobie question. I am using Meeus' Astronomical Algorithims to create a spreadsheet to transform coordinates. I had no problem with precession, nutation, aberration, etc. But, I don't have as good a math background for Motion in Space. I can follow down to the final formulas for x', y' z'. I researched further and found Meeus' source in the Sky Catalogue 2000.0 and that really didn't help me either. I just don't have the math background. Can anyone expound on what I do AFTER I solve for x', y' and z'? Any help greatly appreciated. Thanks, Scott P.S. I added a zip of a bmp of the relevent page in the Sky Catalogue. In any explaination, please keep my genetic deficit in mathematics in mind.