found this out the other night. Although I haven't actually printed out the "manual", the online help was sketchy.
Grid to ground. Initial processing/adjustment in SPC, then define new ground sytem, pick site to use as origin to make N10,000 E10,000 radio button to grid north and whammo, thats all there is to it. BUT, like the rest of us "real world" Surveyors dealing with small projects and wanting to use "True" North, the trick is to set the radio button on "angle", and the REAL kicker is don't check out the convergence at the selected origin site, just type in 00 degrees 00 minutes 00 seconds and THEN click ok. Seems the software applies the convergence to the coordinates.
A solar observation is left to the student to verify. J.D., that is right up your alley!
Dave