NavList:

Thanks to all who contributed.  I will try some of the methods suggested, but at the moment I'm rushing to get ready for the Astrovan's first outing to Newark (Nottinghamshire) Air Museum this coming weekend.

Frank.  We started off with good intentions intending to run from -20 to +20 minutes.   However, life being as it is, by the time we  were getting everything running smoothly, we actually ran from -6 to +16 minutes.  There didn't seem much point continuing after that, and besides lunch was ready.  Like you said, far too short, but we'll know what to do next time.  Knowing quite were to place the Sun's edge was interesting; the horizontal part of the Smith's slightly fuzzy graticule appeared to be about a minute thick.  DaveP