Here's a primer on using magnetic declination data to convert a magnetic bearing to a true bearing. All you need to remember are two things:
1. True bearing = Magnetic bearing + Magnetic declination 2. East = positive (+) degrees, West = negative (-) degrees ====> for both bearing and declination!!!! ============================================================================== The National Geophysical Data Center (NGDC) has a link, viz. http://www.ngdc.noaa.gov/seg/geomag/jsp/struts/calcDeclination that takes you to a tool that can calculate your magnetic declination. I typed in my zip code, got back my latitude and longitude and this yielded a magnetic declination of 12 deg. 0 min. **west** for my QTH for today (i.e. -12 degrees). An associated FAQ link, viz. http://www.ngdc.noaa.gov/seg/geomag/faqgeom.shtml#q5d describes how to use the magnetic declination information to calculate your true bearing. More specifically, you can compute the true bearing from a magnetic bearing by adding the magnetic declination to the magnetic bearing: True bearing = Magnetic bearing + Magnetic declination This works so long as you follow the convention of degrees west are negative (i.e. a magnetic declination of 10 degrees west is -10 degrees and bearing of 45 degrees west is -45 degrees). All magnetic declination and bearing degrees east are therefore positive. Example: My 12 deg. 0 min. west magnetic declination is by convention -12 deg. Both of my long wire antennas point east of north (positive degrees) and have magnetic bearings of +36 degrees and +106 degrees. Thus, said antennas' true bearings are as follows: True bearing of antenna 1 = +36 deg. + (-12 deg.) = 24 deg. True bearing of antenna 2 = +106 deg. + (-12 deg.) = 94 deg. Best regards, -Peter Jernakoff- K3KMS Wilmington, DE www.21centimeter.com This communication is for use by the intended recipient and contains information that may be Privileged, confidential or copyrighted under applicable law. If you are not the intended recipient, you are hereby formally notified that any use, copying or distribution of this e-mail, in whole or in part, is strictly prohibited. Please notify the sender by return e-mail and delete this e-mail from your system. Unless explicitly and conspicuously designated as "E-Contract Intended", this e-mail does not constitute a contract offer, a contract amendment, or an acceptance of a contract offer. This e-mail does not constitute a consent to the use of sender's contact information for direct marketing purposes or for transfers of data to third parties. Francais Deutsch Italiano Espanol Portugues Japanese Chinese Korean http://www.DuPont.com/corp/email_disclaimer.html _______________________________________________ IRCA mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected]
