On Sat, 8 Nov 1997, k.schwarzinger wrote:
> Richard,
>
> thank you very much for your answer about the magnetic North
> Pole.
>
> It is very practically to found the magnetic declination for each
> point of the earth and every year.
>
> I have entered the geographical coordinates of my home :
> Latitude: 47 Degees 14 Min (North) and Longitude: -11 Degrees
> 27 Min (East) and the year 1997.
> I got the message :
>
> "The magnetic declination in 1997 at Latitude 47 Degees 14 Min
> N and Longitude -11 Degrees 27 Min W (!) = 0 Degrees
> 40 Min E.
>
> Why -11 W (West?) ! Why is 'East' not indicated ?
>
> Karl.
> [EMAIL PROTECTED]
Karl:
It is very common in North America (except in geodetic circles!) to treat west
longitudes as positive. The software was written primarily for the use of
Canadians hence the sign bias. The geodetic convention is to treat east
longitudes as positive. Of course, then North Americans would have -66 E! :-)
By the way, there is another geomagnetic field program that can be accessed on
the Internet. It's hosted by the U.S. Geological Survey and is available via
telnet: neis.cr.usgs.gov. Log in ID is QED. This software is not
"North-American-centric."
Here's the information on how to run the on-line program:
GEOMAG provides values of the elements and parameters of the Earth's magnetic
field. The values are estimates based on mathematical models. Values of the
following elements and their rates of change are available:
D - Declination (also called compass variation; east declination is
considered positive, west declination negative)
I - Inclination (also called dip; downward inclination is considered
positive, upward inclination negative)
H - Horizontal intensity
X - North component
Y - East component
Z - Vertical intensity (considered positive downward, negative upward)
F - Total intensity
Positions of the Magnetic Poles and parameters of the centered and eccentric
geomagnetic dipoles are also available.
You will be prompted to select a field model and to enter the date and
geographic coordinates (latitude, longitude, and elevation) of locations of
interest. If you are unsure of how to respond to any prompt, enter a question
mark (?) to get help. If you would like the program to back up to the
previous prompt, enter a caret (^) (that is, the SHIFTed-6 key, not the
UP-ARROW key). If a default response (shown in brackets) is available and is
suitable, you may select it simply by pressing RETURN. To quit the program,
press CTRL-Z (hold down the Control key and press Z).
(Reminder: Enter for help, <^> to back up, to quit.)
Options:
1 = Field Values (D, I, H, X, Y, Z, F)
2 = Magnetic Pole Positions
3 = Dipole Axis and Magnitude
4 = Magnetic Center
-- Richard Langley
Professor of Geodesy and Precision Navigation
===
Richard B. Langley Internet: [EMAIL PROTECTED] or
[EMAIL PROTECTED]
Geodetic Research Laboratory BITnet: [EMAIL PROTECTED] or
[EMAIL PROTECTED]
Dept. of Geodesy and Geomatics Engineering Phone:(506) 453-5142
University of New BrunswickFAX: (506) 453-4943
Fredericton, N.B., Canada E3B 5A3 Telex:014-46202
Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/
===
