The Occultation Machine of HM Nautical Almanac Office
2014 January 26
In the first half of the 20th century, accurate timings of lunar occultations were of great value in monitoring irregularities in the motion of the Moon, and became the standard method of estimating the value of Delta T, the varying difference between Terrestrial Time and Universal Time. Before the invention of programmable electronic computers, the manual generation of occultation predictions was labour intensive, involving many hours of repetitive tasks. This paper describes an ingenious Occultation Machine that simplified the process.