Essen, horizontal view

Internet Project

Observing, Photographing and Evaluating the

Transit of Venus, June 8th, 2004

 Essen, equatorial view

The results of our Observations

Pictures and Positions

Up to now, we got the following pictures and/or position data which can be used to determine the solar parallax following the procedure proposed within this project:

City, Country Name/Organization Example picture sheet of position data
Bad Sobernheim, Germany Emanual-Felke-Gymnasium Sobernheim(Beutel).xls
Barcelona, Spain Tordera2.xls
Cairo, Egypt Deutsche Evangelische Oberschule Kairo3.xls
Essen, Germany Universität Duisburg-Essen
(More results can be found here.) 		Essen(Becker).xls
Isfahan, Iran Isfahan University of Technology Isfahan(Mokhlespour).xls
Isfahan, Iran Hedayatgaran Research Center Isfahan(Akoochekian).xls
Leatherhead/Ashtead, England Robert Jurjevic
(More results can be found here.) 		LeatherheadAshtead(Jurjevic).xls
Menden, Germany Städt. Walram-Gymnasium Menden(Walram).xls
Namibia (v. Grumbkow) International Amateur Observatory Namibia(Grumbkow)3.xls
Namibia (Ohlert) International Amateur Observatory Namibia(Ohlert).xls
Osnabrück, Germany Planetarium Osnabrueck(Haenel).xls
Pforzheim, Germany Kepler-Gymnasium Pforzheim(Friederich).xls
Recklinghausen, Germany Sternwarte
Recklinghausen 		Recklinghausen.xls
Ulm, Germany Universität Duisburg-Essen Ulm(Moeller).xls
Valverde, Portugal Valverde(Gregorio).xls

GONG Network

Because we haven't got enough pictures from observers far from Europe we use the pictures of the solar observatories of the Global Oscillation Network Group GONG in Learmonth (Australia), Udaipur (India) and El Teide (Canary Islands) as additional observational data.
Learmonth, Australia
(The complete results can be found here) 		PositionstabelleLeizi.xls
Udaipur, India
(The complete results can be found here) 		PositionstabelleUdizi.xls
El Teide, Tenerife, Spain
(The complete results can be found here) 		PositionstabelleTdzi.xls

Proof of Exactness

As a first step of evaluation, we have proofed the internal consistence of pictures and positions:

  1. If necessary, we determined the positions by using Bildauswertung.exe. Then, we put the position data into the Excel work sheet Positionstabelle.xls, let it calculate the line fits and transformed the data into a picture which gives an impression of the variance (left column).
  2. The line fits allow to calculate theoretical values for the times of contact. Comparison of these times of contact with the predicted ones may give a second hint for the quality of the data.
  3. In order to proof the quality of the individual data without comparing them with other data of unknown exactness we have calculated theoretical data for the Earth's centre (thanks to Fred Espenak for the hint to the JPL HORIZONS On-Line Solar System Data and Ephemeris Computation Service). Thus, we can compare the observational data with those of a hypothetical geocentric observer.
    hypothetical geocentric observer Geocentre.xls

    The pictures in the right column below show the results of this comparison:

    1. The blue dots represent the values of the solar parallax calculated with the measured positions at 5.30, 5.45, ... UT. The mean value of these results is shown in the upper right corner of the picture (piS (median of measured values)).
    2. The curves show the result of the comparison between the line fits: For each minute, the solar parallax has been calculated using the interpolated x' and y' values. piS (averaged with line fits) means the mean value of these results.
    3. The line fits, additionally, allow to calculate theoretical values for the smallest distance between the the centres of Sun and Venus. A simplified method of determining the solar parallax is to take these minima and to approximate the parallactic shift by their difference. The minima and the corresponding time are shown in the left pictures. The right pictures show the corresponding value of the solar parallax (piS (calculated with rmin)). The advantage of this approximation is its independence of the orientation of the fotos!

City Summery of position data Determination of the Solar Parallax by
Comparison with geocentric data
Essen (theoretically)
(calculated with the aid of JPL Horizons)
Bad Sobernheim
Barcelona
Cairo
Essen
Isfahan (Akoochekian)
Isfahan (Mokhlespour)
Learmonth
Leatherhead/Ashtead
Menden
Namibia (v. Grumbkow)
Namibia (Ohlert)
Osnabrück
Pforzheim
Recklinghausen
Ulm
Valverde

The following table combines all "internal" results for the solar parallax and gives an impression of the fidelity of our observational data.

 line fit  rmin  median 
Ashtead/Leatherhead4.13.012.9±7.8
Essen7.95.77.6±1.3
Menden10.07.510.4±6.6
Osnabrück17.09.020.7±6.8
Pforzheim4.40.15.1±3.0
Recklinghausen8.57.38.3±1.5
Sobernheim4.23.25.1±2.3
Ulm8.67.09.5±1.9
Valverde5.70.933.9±6.7
Isfahan (Akoochekian)18.712.05.5±0.8
Isfahan (Moklespour)11.910.815.5
Cairo10.11.512.6±3.1
Learmonth8.96.99.0±0.8
Namibia (v. Grumbkow)10.84.411.4±2.7
Namibia (Ohlert)10.47.010.7±0.6

First Comparisons between sites of our project

The measured positions do not allow to determine the solar parallax by comparing European data. We, therefore, concentrate on combinations of European sites with those from outside of Europe.

The following tables show the calculated values for the solar parallax in arcseconds which we have determined by the methods described above.

Mean values from the combination of the line fits

VIAIMCLNGNO
A19.19.44.56.86.393.39.4*
E17.014.56.614.58.6*8.1*8.8*
M25.220.410.918.411.17.5*9.8*
O4430293214.98.7*10.9
P19.77.76.76.37.0*6.9*8.4*
R17.517.94.113.98.49.310.0
S9.812.74.09.28.5*6.1*8.1*
U26.315.64.314.78.8*10.1*10.7
V-12.54.312.88.1*4.67.3
IA--11.57.5*11.812.3
IM-9.811.910.815.5
C-8.2*12.013.1
L-11.38.7

Comparisons of the minimal distances of the centres of Sun and Venus

VIAIMCLNGNO
G0.912.08.61.59.83.612.0
A7.47.11.33.95.17.1
E14.510.64.49.0*6.46.88.6*
M19.813.06.811.58.87.19.7*
O23.014.98.713.89.58.010.5
P2.83.92.61.35.62.75.1
R25.313.913.811.47.17.79.3
S8.07.71.44.37.04.67.3
U21.212.45.912.67.28.09.7*
V-4.61.60.26.03.86.9
IA--8.46.50.98.6*
IM-3.29.84.712.5
C-7.34.48.2*
L-2.00.4

Mean values of the direct combinations of the measured positions

IAIMCLNGNO
G5.0±0.820.612.6±3.18.9±0.7*11.5±2.7
A36.6±6.05.821.2±6.29.8±4.110.5±3.810.1±1.5
E11.413.8±5.89.0±0.5*8.0±1.9*8.9±0.4*
M21.2±4.932.1±0.811.2±4.811.4±1.511.3±0.0
O24.2±6.110.910.8±2.1
R11.713.1±3.98.7±0.410.1±2.110.4±0.6
S11.3±5.99.7±4.09.27.5±1.0*8.1±2.5*7.8±0.8
U14.6±3.49.016.5±5.88.8±0.5*10.2±1.7*10.6±0.6
V15.98.582±1642±18.6±4.09.6±2.2
IA-21.44.6-
IM19.111.615.9
C6.7±1.1*14.3±4.713.3±3.4
L11.4±1.78.8±0.0*

Some graphical representations

The combination Bad Sobernheim/Cairo clearly demonstrates the advantage of the line fits. The comparisons between Ulm/Learmonth and Essen/Namibia below show some of the most satisfying results.

Bad Sobernheim/CairoEssen/NamibiaGEssen/NamibiaOUlm/Learmonth

Some remarks to the difficulties due to the size of the solar picture, the orientation of the pictures and to the restichtions of Bildauswertung.exe will be given later.

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Udo Backhaus
last modification:  December 5th, 2007