(9) Metis verfinstert HIP 78193
What we know from the occultation and the light curve:
-the form of a potato looks sensefull
-the rotation axis is near the ecliptic
-at the occultation we have seen Metis on a position near the minor axis.
-the albedo was 25% to low.
Metis is one of the 400 minor planets with a rotation model in the DAMIT-Database.
There are 2 models. An old convex model and a new more complex nonconvex model. It´s interesting to compare models and reality.
The picture shows both models.
2 times at the equator and one time on the pole.
The eclipse is a possibility to check the models:
The old convex model fits better than non-convex model 716.
The deficits of model 716 were also visible at a eclipse from 2008 (JD 2454721.76736)
It make sense to use only model 111.
Also other eclipses fits well to model 111:
The DAMIT database delivers always 2 views. One with the phase at the calculated time and one without phase-effects.
The difference between the picture-brightness is 13088115 : 19202888 or 30% That´s nearby the measured value of 25%
The measured difference in the Albedo is completely explainable by the phase.
The following animation shows the rotation at the 7. of March 2014. 72 pictures with 5 degree difference are connected to get this result.
The model is orientated north-south east-west.
As presumed the rotation axis is near the equator.
But how does the model fit to the measured light curve?
The light curve of the model fits the reality. There are 2 mountains. The first one has the right value and also the valleys are perfect.
On the second view there are differences. The second mountain is too low.
-the model is good but not perfect.
During the maximum the brightness of Metis is 20% higher than during the occultation. But the major-axis is in the maximum not 20% longer.
The minor planet is not a perfect rotation-ellipsoid. The rising brightness depends on a better illumination on the northern part of asteroid.