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Schröter Effect 2017


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About this observation
David Basey
Time of observation
07/11/2017 - 09:56
358mm Newtonian

Since early May I have been able to make visual observations of the planet Venus on 31 separate days. Part of the each observation is to measure the apparent phase of the planet and compare this to the theoretical value. As usual, for much of the apparition, the observed phase is less than that dictated purely by geometric concerns. This is the well known Schröter Effect.

With the 2017 elongation approaching its close I thought it might be of interest to display the results. Observations were normally made both in yellow light with a Wratten 15 filter and blue with a Wratten 47.

Notice how:-

  1. The deficit is greater in blue than yellow light.
  2. The lag seems to increase with increasing phase up to about 0.8 and then decrease close to zero as it approaches 0.95. 
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