Flamsteed AS Gilbert Satterthwaite

Flamsteed Astronomy Society

“Being an astronomer at Greenwich in the 1950s”

a talk by Gilbert Satterthwaite — March 7, 2011

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Report by Chris Sutcliffe

Gilbert is Chairman of the Society for the History of Astronomy (SHA), erstwhile leader of an MSc course at Imperial College, and famed for his work at Greenwich with Airy’s Transit Circle.

Gilbert began by explaining how he came to work as an astronomer. He became interested in the subject at the age of 11, and after studying mathematics and applied physics in the 6th form at Weymouth Grammar School in 1951, he went to an astronomy class at the college of higher education where he met Dr Arthur Alexander, Deputy Director of Education for Dorset.

Having received little encouragement from talking with his 6th form career adviser about a career in astronomy, he had some inspiration. He bought the book “Worlds without End” by Sir Harold Spencer Jones, Astronomer Royal, and sent the book to him requesting him to sign it. To his delight, he did sign it, and encouraged by this, Gilbert wrote to Sir Harold to enquire about job prospects in Astronomy. He received an information pack and an application form.

There were three possible career paths -- a first-class maths degree from Cambridge – top; any degree - half way; A levels or other qualification - bottom of the ladder.

He was successful in getting an interview and saw Dr Atkinson and Mr Sims. The questions became progressively harder, but Mr Sims helpfully gave clues to answer the questions. He was offered a job!

Gilbert joined the Meridian Department and was trained up on the Airy Transit Circle — a big learning curve. Airy’s Transit Circle was used to make two measurements - the time at which a star crosses the meridian, as it appears to travel from East to West across the sky, and the angle of the star above the horizon. From these measurements an astronomer can calculate the star’s celestial coordinates - its precise position in the sky, relative to other stars. If the star's coordinates are already known, then the transit of a star across the meridian could be used to check Greenwich Mean Time very precisely.

Gilbert worked a 5½ day week and had 6 weeks holiday.

Early on, he had a crash course in positional astronomy and Mr Sims was the best maths teacher he had ever had.

In addition to stars, Gilbert observed the Moon using the Airy Transit Circle, but the Moon’s motion is complex.