First evaluations of some uploaded images had been presented on page First Results.

Project Results

Positions of Mercury as measured on series of pictures taken from space (SDO), IAS (Namibia) and Hannover (Germany)

The main goal of this project was to visualize the parallax effect of Mercury that means the fact that during its transit Mercury is found at slightly different positions on the solar disc when it is observed from distant places on Earth at the same time. The effect was to be proved by taking simultaneous pictures of the transit and by combining those pictures later. For this reason, a platform was offered for sharing own images of the transit with participants all over the world.

We got pictures from 23 sites, mainly in Europe but, fortunately, in Southern Africa and Southern and Northern America, too.

First combinations


Hannover, Germany - SDO, Orbit 11:30 UT	Lippstadt, Germany - IAS, Namibia 11:16 UT	Geseke, Germany - Rosario, Argentina 18:37 UT	Rosario, Argentina - Pointe Saint Mathieu, France 18:37 UT

First of all Mercury's parallax became visible by a combination of an earth-bound photo with a SDO-picture, taken from a geosynchronous orbit with a radius of about 42000 km. Those combinations can be made especially easily because the orientation of the SDO-images is exactly known and the baselength for the parallax effect is about sixtimes as long as in the case of two earth-bound images.
Nevertheless, only a few days later R. Schünecke and A. S. Kleiman sent satisfying combinations of pictures taken in Argentina and Europe.

Combination of nearly simultaneous images

The second goal was not only to visualize the parallactic effect but also to measure its size. Therefore, the orientation of the images had to be determined very precisely. Only very few participants used the method of taking "double exposed" pictures. Fortunately, on transit day the Sun showed a prominant group of sunspots which allowed another (but less sensitive) determination of the Sun's orientation on the images. Some of the uploaded pictures are sufficiently simultaneous and allow direct comparisons, that means precise combinations and measurements of Mercury's positions with respect to the same direction of reference. With the precisely measured positions the solar parallax can be derived by using the method described in the project page Example and in the additional paper (English version and German version).

Some of the most satisfying combinations of single and the results of their evaluation are the following:

	Resulting solar parallax
Caracas, Venezuela - Lippstadt, Germany 13:30:00/13:30:03 UT (E. Torres/R. Schünecke)	π_S=8.4"
Caracas, Venezuela - Hannover, Germany 14:00:00/14:00:01 UT (E. Torres/U. Backhaus)	π_S=8.9"
IAS, Namibia - Hannover, Germany 14:00:00 UT (R. Anton/U. Backhaus)	π_S=8.5"	Animation
IAS, Namibia - Lippstadt, Germany 14:00:00 UT (R. Anton/R. Schünecke)	π_S=8.0"	Animation
Hannover, Germany - Big Bear Lake, California 17:30:00/17:30:11 UT (U. Backhaus, G. Schneider/J. M. Pasachoff)	π_S=9.4"
Cologne, Germany - Big Bear Lake, California 16:00:00/15:59:45 UT (M. Junius, G. Schneider/J. M. Pasachoff)	π_S=8.4"
Bochum, Germany - Caracas, Venezuela 15:00 UT (A. Knülle-Wenzel, E. Torres)	π_S=10.7"	Animation

The mean solar parallax of the comparisons between these selected pictures from two distant sites is π_S=8.9"±0.4".

Comparison between selected series of images

Comparison between Earth-bound images and those of the Solar Dynamics Observatory (SDO)

The third goal of this project was to derive the distance to the Sun, i. e. the solar parallax, as exctly as possible. The central task for this goal is the determination of the images' orientation. As stated above, this task is difficult and the final results depend from measurement errors very sensitively.
One possibility of proving not only the quality of the images but also that of the determination of the orientation is to compare the measured positions of Mercury with those measured on the SDO images.

	Superposition	Measured positions	Determination of the solar parallax
SDO
Big Bear Lake, California (G. Schneider/J. M. Pasachoff)
Bochum, Germany (A. Knülle-Wenzel)
Caracas, Venezuela (E. Torres)
Cologne, Germany (M. Junius)
Greiz, Gemany (Astron. Gesellschaft, Greiz)
Hannover, Germany (U. Backhaus)
IAS, Namibia (R. Anton)
Jankowice, Poland (G. Przybyla)
Niedzwiedz, Poland (M. Talar)
Pointe Saint Mathieu, France (T. Kunzemann)
Tenerife, Spain (M. Federspiel)

By integrating all these comparisons of the uploaded series of pictures with the SDO series we attain a very satisfying result:

The mean solar parallaxes of these comparisons are	π_S=9.22"±0.15"	(measured values)
	π_S=8.97"±0.15"	(fitted values)

The mean solar parallaxes of these comparisons are π_S=9.22"±0.15" (measured values)

π_S=8.97"±0.15" (fitted values)

Comparison between series of images taken at distant sites

Because of the much shorter baselength parallax measurements from Earth respond even more to errors of the position measurements. Therefore, not all of the possible comparisons between series of Earth-bound transit images yield acceptable results. The best of them are presented below:

	Measured positions	Determination of the solar parallax
IAS, Namibia Hannover, Germany SDO
Big Bear Lake, California Hannover, Germany
Caracas, Venezuela Hannover, Germany
Caracas, Venezuela IAS, Namibia
Greiz, Germany Caracas, Venezuela

The mean solar parallaxes of these comparisons between two distant sites are	π_S=8.2"±0.5"	(measured values)
	π_S=6.9"±0.6"	(fitted values)

The mean solar parallaxes of these comparisons between two distant sites are π_S=8.2"±0.5" (measured values)

π_S=6.9"±0.6" (fitted values)

Conclusion

Perhaps, the main results of this project can be summed in the following sentences:

Mercury's parallax effect could be clearly verified and its measure could be estimated. The first superpositions of nearly simultaneously taken images have been very satisfying!
The quantitative evaluation of the pictures proved to be very (!) sensitive.
The determination of the images' orientations by using the sunspots is much less exact than by evaluating double exposed images. The reason is that the distance between sunspot and the center of the solar disc is much smaller than the distance between both solar centers. Unfortunately, only very few participants used the method of double exposuring.
Because of the about sixtimes as long baselength comparisons between SDO images and earth bound images yield considerably better measures of the solar parallax than comparisons between images taken at distant sites on Earth.
Nevertheless, all in all our results are much better than we could expect lasting for weeks.

Editor:

Udo Backhaus

last update: 2019-01-25

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Transit of Mercury, May 9th, 2016