I guess there are not tracking "Hollywood" animals, probably only those
in the "wild".
Have Fun & THANKS very much,
Brooke Clarke, N6GCE
R.Hooijenga wrote:
Hello sundialeers,
I think I could guess the basics behind the method Brooke describes.
From sunrise and sunset, get noon. True noon,corrected with EOT and
expressed in UTC, would give you longitude, thus:
NOON(utc) - 12 hours = (degrees WEST) / 15
From sunset and sunrise, we also have the half daylight length t, for which
we have our T-shirt formula:
- cos(t) = tan(decl) tan(lat)
which we solve for lat.
How sunset and sunrise are determined, I don't know (yes, a photocell, but
what constitutes "sunset"? In Holland, it does not get dark anytime during
the night, this time of year - then again, it certainly is a lot darker that
during the day, even if it is raining again).
Example
Assume we see a sunrise at 17:00 utc and a sunset at 01:00 (which is
conveniently written as 25:00); we get
noon = (25+17)/2 = 21.00 utc.
eot is about zero today (June 13), so we get corrected noon is also 21.00
utc
longitude = (15*21 -12) degs West, or 135 degs West.
Also, t = (25-17)/2 = 4 hours.
Now the half day length is 4 hours, corresponding to 60 degrees.
The declination of the sun is 23.23 degrees north today, so:
- cos (60) = tan(23.23) tan(lat)
-0.5 = 0.429 tan (lat), so that tan (lat) = -1.166 and finally lat = -49.37
degrees, or 49.37 degs South
Our animal was at 49.37 South, 135 West today - wherever that may be.
Rudolf
-----Oorspronkelijk bericht-----
Van: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Namens Brooke Clarke
Verzonden: maandag 13 juni 2005 21:06
Aan: sundial@rrz.uni-koeln.de
Onderwerp: Deriving Lat & Lon from Sunrise & Sunset
Hi:
There is an animal tracking system that records the times of sunrise and
sunset (along with the date and time) and then sends that (and some other
stuff) to a central station. In the central station they process the
sunrise and sunset times to find out the Lat and Lon of the animal (maybe to
1 degree).
-
--
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
-
