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This event involves astronomical observations, but if your group is unlucky with the weather, you can still participate.
Determine your geographical latitude!
The Astronomy On-line groups are located in 39 countries all over the world. We would like you to determine your geographical latitude and to report it to us, so that we can find out how the groups are distributed from south to north. This is actually quite easy by means of simple astronomical observations.
We suggest that you use one of four different methods, but we would prefer that you try to use the first or the second one, if at all possible.
By determining the altitude of the Polar Star over the northern horizon, you will be able to determine at the same time your geographical latitude.
A very detailed explanation is available. Please read it carefully and use one of the sighting methods described in that text to make this observation during one of the coming evenings.
Remember, that the altitude of the Polar Star is directly equal to your geographical latitude!
If the weather is partially clouded, or if you live south of the terrestrial equator, you will not be able to see the Polar Star. In that case, we propose that you observe the altitude of the Sun at local noon. That is when the sun reaches the highest point in the sky - depending on location, but in the example below this happens at 1215.
You should report the Shadow Length "SL" during Local noon, as well as the Gnomon Height "GH" - both marked with red colour.
Detailed instructions are available in connection with the Erathostenes Collaborative Project. There is also much information in connection with the determination of Local Noon (within the Lunar Eclipse Project) By using a simple gnomon, this should be a quite simple observation.
Once you have measured the altitude of the Sun, it is easy to determine your geographical latitude by means of the following formula (all angles expressed in degrees):
Your geographical latitude = 90 + solar declination - solar altitude.
If you live far south and see the Sun towards the North, you should add 90 deg to the measured altitude in the following calculation.
The solar declination is as follows during the next days:
Day 12 h UT
Sep 14 +03 Deg 17'
Sep 15 +02 Deg 54'
Sep 16 +02 Deg 31'
Sep 17 +02 Deg 08'
Sep 18 +01 Deg 45'
Sep 19 +01 Deg 21'
Sep 20 +00 Deg 58'
Sep 21 +00 Deg 35'
Sep 22 +00 Deg 11'
Sep 23 -00 Deg 12'
Sep 24 -00 Deg 35'
Sep 25 -00 Deg 59'
Sep 26 -01 Deg 22'
Note that at "equinox", on Sept 22-23, the Declination is equal to Zero, giving both day and night equal to exactly 12 hours.
For instance, on September 16, the Solar Declination is equal to + (03 +31/60) Deg = 3.5 Deg.
If you measure a solar altitude of 60 degrees on that day, your geographical latitude is 33.5 degrees North (90 + (+3.5) - 60 = +33.5).
Submit your results to: EAAE European Student Project Group
Once we have received all results we will make a combined Table and map, which will be made available.
Good luck with your observations !
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