Visit to the Royal Observatory, Greenwich under the guidance of Gilbert Satterthwaite, ROG Astronomer Saturday, March 5th, 2008 12 TARS spent a fascinating day listening to Gilbert explain the techniques used to produce the nautical Almanac on which Arthur Ransome and countless others have depended for obtaining their position at sea.  This included a demonstration of the Airey Transit Circle (on which Gilbert took the last transit measurements before the ROG ROG moved to Herstmonceux), an explanation of the Harrison time-pieces and their pivotal role in determining longitude at sea, and a spectacular show in the new Planetarium.