Description
In January 1997, at the Observatsrio Nacional (ON), Rio de Janeiro, Brazil, CCD observations of the solar diameter with a Danjon astrolabe equipped with a variable angle reflecting prism began. This prism is operated manually and enables to observe the Sun many times per day and all year round on the Southern latitude {phi}=-22{deg}54'. Thanks to this and owing to a large number of sunny days at Rio de Janeiro, a high density of observations was achieved - 2900 East and 1730 West observations during the first 18 months.
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