British Astronomical Association

Supporting amateur astronomers since 1890

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A method for deriving Cousins R magnitudes from UCAC4 data

We describe a method for deriving Cousins Rc magnitudes from r, B, and V stellar photometry in the UCAC4 catalogue, valid in the range 9 < Rc < 16. The source of the majority of UCAC4 reference star photometry is the AAVSO Photometric All-Sky Survey (APASS) catalogue. Version 433 of the software Astrometrica is updated so that, provided the UCAC4 catalogue is selected as the reference, Rc magnitudes are calculated using our derived transformation, namely: Rc= r – 0.108(B–V) – 0.132.

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Figure 1: The Worthington Residence

James H. Worthington (1884−1980): A quest for totality, observatories & Martian canals

James Henry Worthington became a prominent amateur astronomer during the years preceding the Great War, mainly because of his expeditions to distant solar eclipse tracks and observatory sites, but also because of his interest in the Martian ‘canals’ and his friendship with Percival Lowell. Just prior to the start of the War he built a major observatory at Four Marks in Hampshire, which he generously invited BAA members to use whenever they wished, at least until he moved permanently to the USA.

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