For this project we propose to photograph Sun and Venus during the transit all quarters of an hour, i.e. exactly at 10.30, 10.45, ..., 4.15, 4.30 UT. (If you are not certain about the difference between your local time and Universal time look at heavens above.)
In order to be able to measure Venus' position on the solar disc the exact orientation of the pictures must be known. Non professional observers can solve this problem by exposing their pictures twice. Tips for that procedure are given in our photographing page.
During the transit several additional activities are recommended:
Additional determination of the Sun's angular radius (for instance, by measuring the size of pin hole pictures of the Sun or by measuring the time which the Sun needs to move by its own diameter, see the project measuring the angular radius of the Sun).
The position of Venus on these pictures may be measured with the help of the little program evaltransitpicts.
In the case that clouds have made photographing impossible at the fixed moments, the positions may later be determined by interpolation between pictures taken at earlier and later moments (see below).
The measured positions of Venus at the above proposed points of time may also be uploaded via our data exchange page.
The complete position data made by a single participant can be filled into the worksheet tableofVenuspositions.xls which calculates and displays the parameters of the best linear fit to these positions. The line fit will allow to interpolate to the above mentioned points of time. Additionally, the line fit will allow to derive the contact times by extrapolating the observational data. This is, for instance, be done by the program evaltransitpicts. The so determined contact times may be uploaded via the data exchange page of our contact times project.
the combination of the line fits of two distant sites, again with the program evaltransitpicts.
Example comparison of theoretical 2012 results
If you don't find any data from distant sites suitable for being combinated with your own measurements it will temporarily be possible to compare them with calculated geocentric positions. (The calculation of geocentric data is possible without knowing the absolute size of the solar system!)
Example comparison between topocentric and geocentric results