British Astronomical Association

Supporting amateur astronomers since 1890

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New measurements and analysis of the β Cephei star V909 Cassiopeiae

V909 Cas is a little-studied example of a β (Beta) Cep pulsating variable star, located in the OB association Cas OB8 in the Perseus spiral arm of the Milky Way. Photometric observations in 2016-’17 provided thirty new times of pulsation extrema and enabled its mean pulsation period to be determined as 0.2067798(1)d. From spectroscopic observations we determined its interstellar extinction and absolute magnitude and luminosity, and located it with other β Cep stars in the OB instability region of the H-R diagram.

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128-5 McKim transit1

The 2012 solar transit of Venus

Results from the 2012 June solar transit of Venus are illustrated and discussed, and make an interesting comparison with our recent report on the 2016 transit of Mercury. As in previous years, observers were able to time the contacts, to see the ‘Black Drop’ effect (caused by inadequate resolution, but often enhanced by turbulence) and to record the ring of light around the unilluminated limb at both ingress and egress. This will be the last transit of Venus until 2117 Dec 11, unless we include the event of 2020 Jun 3, when the planet will be silhouetted against the solar corona.

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