Time vs. Longitude Calculation Question

[Guest jomala]

I found a cache (Latitude and Longitude), in Georgia, where the clue to the longitude is given as follows:

"I hid this cache on a hot, sunny August day. The morning paper's weather section not only confirmed that it would be sunny but that sunrise in Atlanta would occur at 7:06 am and sunset at 8:06 pm. As the cache is somewhat east of metro Atlanta sunrise and sunset there occured about 5 seconds earlier. By my atomic clock the exact sunrise there was at 7:05:55.0212 (or 5 minutes and 55.0212 seconds after 7am). Sunset was at 8:05:55.0212 pm." The calculation should be made based on time/longitude from Greenwich using UTC.

Can someone explain how to do this calculation and what the formula would be.

Thank you very much!

[Guest Jors]

A good starting point is probably to assume solar noon at the cache being halfway between sunrise and -set, and using the difference to noon at Greenwich.

The times given in the clue is not in UTC, but Eastern Time,(I guess) and it has to be converted to UTC by adding 5 hours (Verify me on this).

 

Time difference multiplied by 15 gives longitude difference, just figure out the plusses and minusses...

 

Hope this puts you on some track, and hopefully not the wrong one!

[Guest erik88L-R]

Jors is quite right, except that if the cache were placed in the summer when Daylight Savings Time is in effect the offset would be only 4 hours. For a good primer play the longitude game at:

http://www.pbs.org/wgbh/nova/longitude/

[Guest Steveonne]

Try this link, jomala. It should have some info you're looking for.

 

http://forums.Groundspeak.com/ubb/Forum2/HTML/000635.html

[Guest Jors]

Any verdict on whether EoT is taken into account?

(EoT = Equasion of time = diff between mean sun and true sun)