Observing the Sun – 25th May 2006

John Chapman-Smith, a member of the council of the Society for Popular Astronomy, and a past director of its Solar Section, gave us a talk on the practical aspects of Observing the Sun. No talk on this subject would be complete without serious warnings about the dangers involved. He stressed the importance of using projection to observe the Sun indirectly, and of taking precautions like capping or removing finder scopes, reducing telescope aperatures, and not using telescopes with any flammable components in them. Even looking directly at the Sun with the un-aided eye will cause damage. Anything which concentrates the infra-red heat radiation can be very dangerous. Some of his slides showed the damage sustained by filters and eyepieces. Eyes are much more easily damaged.

Having covered the safety aspects thoroughly, he then went on to describe the kinds of features that can be observed, and how they should be recorded. He then explained how more experienced observers might use various safe filters to photograph and observe the Sun, and added more cautionary tales about some of the un-safe filters that should never be used. He ended his talk by showing us some images taken using Hydrogen Alpha and Calcium K filters. These allow observers to see more features, including filaments and prominences, but they are still quite expensive. Even though they do filter out the harmful radiation when used properly, observations must still be carried out taking all appropriate precautions.

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