Observation by David Basey: Schröter Effect 2018

Uploaded by

David Basey

Observer

David Basey

Observed

2018 Oct 24 - 09:10

Uploaded

2018 Oct 24 - 09:24

Objects

Venus

Planetarium overlay









Constellation

Phoenix

Field centre

RA: 00h54m
Dec: -57°19'
Position angle: +101°02'

Field size

0°09' × 0°05'

Equipment
  • 358mm Newtonian
Target name

Venus

Title

Schröter Effect 2018

About this image

During the current Eastern elongation of Venus I have been able to make observations on 22 separate days. In most cases it has been possible to record the planet using three separate filters, W15 (Yellow), W47 (Blue) and W25 (Red).

Part of each observation is to record the apparent phase. The difference between the observed value and the theoretical dictated by purely geometrical concerns is the well known Schröter effect.

As usual, for much of the elongation, the observed phase is less than theoretical. The effect decreases and ultimately reverses as inferior conjunction approaches. If it did not the planet would disappear prior to conjunction!

Notice how:

  1. The phase in blue light is consistently less than in yellow and the blue trend line runs nearly 'parallel' to that for yellow.
  2. The phase in red light starts out smaller than the yellow but at phases less that about 0.7 become greater.
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