README for the Leeds Directory of Magnetic Declination Data and Software 7 September 2006, S. Lubker The declination data file (gufm1) and Fortran program (calc_di_vs_time.f) were received in 2005 from KNMI (Frits Koek) in a zip file. The data and software are described in the following message excerpt: =>Date: Thu, 21 Apr 2005 13:56:26 +0200 =>From: "Frits B. Koek" =>To: "Scott Woodruff" =>Subject: Re: US Maury and Met Journals Collections . . . =>1. Referring to the first question about the magnetic variation, I =>attached a fortran program and a datafile that I received from Leeds =>University (UK). The program calculates the magnetic variation at any =>position and year between 1590-1997, which I think suits your needs. . . . -r--r--r-- 1 sjl coads 299882 Aug 31 13:36 Leeds.zip -rw-r--r-- 1 sjl coads 16390 May 13 2003 calc_di_vs_time.f -rw-r--r-- 1 sjl coads 751886 May 13 2003 gufm1 Andrew Jackson, Art R. T. Jonkers, Matthew R. Walker, Four centuries of geomagnetic secular variation from historical records, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences , Volume 358, Issue 1768, 15 Mar 2000, Pages 957 - 990, DOI 10.1098/rsta.2000.0569, URL http://dx.doi.org/10.1098/rsta.2000.0569