Re: learn something new every day
On 11/11/98 Greg Milsom wrote, >Today I learned that one of the reasons my new dial was not as exact as >I had hoped was because the magnetic variation I was using to align the >dial was several years old and that magnetic variation does in fact >change over time. I am now searching material on the web that seems to >indicate that the Equation of Time figures that are in the back of >Albert Waugh's book may also be somewhat old and need updated for 1998. >Please let me know if the EoQ number do in fact change and how I can >calculate the change using an Excel spreadsheet. Dear Greg, It does change, alas. A while ago I created an Excel spreadsheet, based on the equations in Meus' book which seemed to get correct answers. I only set it up to calculate single days, but that could be modified. Since it was created solely for my own amusement, it comes with little or no documentation, but if you want to play with it, let me know (and what encoding standard your e-mail browser uses) and I can try to send it to you. Peter Mayer -- Peter Mayer | [EMAIL PROTECTED] Politics Department | 'phone:+61.8 8303 5606/5610 University of Adelaide | FAX: (+61.8) 8303 3446 Adelaide, SA 5005 | Time Zone: GMT +9.5 hrs (April-October) AUSTRALIA |GMT +10.5 hrs(November-March) --
World Magnetic Model
http://www.ngdc.noaa.gov/seg/potfld/DoDWMM.shtml
learn something new every day
Today I learned that one of the reasons my new dial was not as exact as I had hoped was because the magnetic variation I was using to align the dial was several years old and that magnetic variation does in fact change over time. I am now searching material on the web that seems to indicate that the Equation of Time figures that are in the back of Albert Waugh's book may also be somewhat old and need updated for 1998. Please let me know if the EoQ number do in fact change and how I can calculate the change using an Excel spreadsheet. thanks.
Re: magnetic variation software
The magnetic declination changes slowly with time. The Geological Survey of Canada's on-line magnetic declination calculator gives for your coordinates: 1995 10d 11m W 1998 10d 22m W 2000 10d 30m W You can get a DOS or Windows program for do-it-yourself use at http://geomag.usgs.gov/ -- Richard Langley Professor of Geodesy and Precision Navigation On Wed, 11 Nov 1998, Greg Milsom wrote: >Is anyone aware of a shareware or freeware program available on the web >that will compute the magnetic variation for various Longitude and >Latitude coordinates? I am trying to orient my homemade dial and come up >with slightly different variations depending on who I talk to. Anywhere >from 9d W to 10.7d W. My coordinates are 39d N and 77d W. Is there a >'simple' or maybe not so simple formula that I could program an Excel >spreadsheet to calculate. Thanks. >-- > >Fiddler's Green >We Design and Install Renewable Energy Systems >"Solar Energy...Live the Good Life!" >Greg Milsom, Owner >PO Box 1200 >Bowie, Maryland 20718 >Phone/Fax: (301) 210-7669 >http://www.radix.net/~green > === Richard B. LangleyE-mail: [EMAIL PROTECTED] Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142 University of New Brunswick Fax: +1 506 453-4943 Fredericton, N.B., Canada E3B 5A3 Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/ ===
Re: magnetic variation software
Greg Milsom wrote: > > Is anyone aware of a shareware or freeware program available on the web > that will compute the magnetic variation for various Longitude and > Latitude coordinates? I am trying to orient my homemade dial and come up > with slightly different variations depending on who I talk to. Anywhere > from 9d W to 10.7d W. My coordinates are 39d N and 77d W. Is there a > 'simple' or maybe not so simple formula that I could program an Excel > spreadsheet to calculate. Thanks. > -- > > Fiddler's Green > We Design and Install Renewable Energy Systems > "Solar Energy...Live the Good Life!" > Greg Milsom, Owner > PO Box 1200 > Bowie, Maryland 20718 > Phone/Fax: (301) 210-7669 > http://www.radix.net/~green Greg, I wouldn't waste my time by aligning your dial to a compass. It is real tough to get it accurate enough. Better to use the shadow of the sun to align your dial. There are several techiques and most use software to find the direction to the sun at a given time. NASS has a program (Dialist Companion) which will help align a dial. Good luck bob
magnetic variation software
Is anyone aware of a shareware or freeware program available on the web that will compute the magnetic variation for various Longitude and Latitude coordinates? I am trying to orient my homemade dial and come up with slightly different variations depending on who I talk to. Anywhere from 9d W to 10.7d W. My coordinates are 39d N and 77d W. Is there a 'simple' or maybe not so simple formula that I could program an Excel spreadsheet to calculate. Thanks. -- Fiddler's Green We Design and Install Renewable Energy Systems "Solar Energy...Live the Good Life!" Greg Milsom, Owner PO Box 1200 Bowie, Maryland 20718 Phone/Fax: (301) 210-7669 http://www.radix.net/~green
