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On this page I collect my observations of the double star Castor in the constellation Gemini / Twins.
The double star Castor (alpha Geminorum) in the constellation Gemini / Twins is the Northern "twin" star of Pollux. It is a bit fainter than the latter, but nevertheless called alpha Geminorum - and a double star (Pollux is a simple star). I need a magnification of about 100 x to separate the double star (4.9"), but even then both stars are still very close together in the field of view (50 x was possible but hard to see).
Distance: 4.9" (Stoyan)
Distance: 52 light years (Stoyan)
Ranking: *** (Stoyan)
Castor in the constellation Gemini in May and M 35 at the other end of the constellation