Margins of the Millenium Eclipse

It is not easy to compute accurately, where the margins of the full lunar shadow will be during the Wednesday August 11 eclipse. Fortunately it had been done by specialists already, and the remaining task was to plot the margins into maps. We have employed the results of the computation by dr. Alan Fiala from the US Naval Observatory (www.lunar-occultations.com/iota/0811eclp.htm). They give the line, where at least for some seconds no part of the glaring solar margin will appear even at the bottoms of lunar valleys and saddles.

The shadow path is given by means of the geographic coordinates and so it can be plotted to such maps only, which include a coordinate grid. In case of Austria, the atlas Österreich Touring (scale 1:250000, grid each quarter degree) from Freytag&Berndt has been at first employed, in case of Hungary, the map distributed by GeoMedia (1:300000, grid each ten minutes with emphasized halves of a degree) has been the only choice. The grids of both maps are without a legend, but it can be easily added using any school atlas. Then I have bought maps of Austrian lands 1:200000 (Freytag&Berndt), which are seven altogether, of course, but for the eclipse margins just four are needed (No. 1, 2, 4 and 6). If you travel to Austria, definitely buy them.

GeoMedia offers a map of Austria as well, including a legend for the grid, but the grid is a good deal rotated, so that it does not match the legend at the bottom side, e.g. The legend at the right side has an error of half a degree, moreover! We have then checked the grids in another maps as well, and found them to have no gross error. For that purpose, we have employed approximate coordinates of settlements as they are given in the database of the German ephemeris service for satellite visibility (http://www2.gsoc.dlr.de/satvis).

Plotting of eclipse margins takes some time, and so we offer the results as strips of maps some four centimetres wide, with axis being some two kilometres from the eclipse margins. The eclipse margin is always marked, together with the line running two kilometres inside the shadow.

The marked straight lines hold for the sea level. The lunar shadow is cast obliquely onto the Earth surface, and so the real shadow margin should be plotted as humpy, shifted to the SSW some six tenths of the altitude of the given landscape. The maps 1:300000 and 1:200000 have the humpy lines of the optimum sites marked by a color pencil. Shifts over one kilometer appear just in Alps on the southern margin of the eclipse.

Our strips of maps should be accompanied by some printed publication offering an overview of the shadow path through the whole Europe. It is almost necessary to have also the original color maps. It is difficult to find your way on the narrow reproduced strips, and when printed black and white they are even difficult to read.

The color strips are available at http://astro.sci.muni.cz/pub/hollan/eclip99/mapy. You can find there also the text files with the coordinates of margins and a file with names of some sites lying two kilometres inside the shadow, where the line of most dynamic view of the eclipse runs.

Electronic publishing and black and white reproduction of the strips had been permitted by freytag & berndt, Varhulíkové 120, 170 00 Praha 7, phone/fax: +42 (2) 800 161, freytag.cirhan@oasanet.cz, in case of map of Hungary by Kartografie Praha, Fr. Křižíka 1, 170 00 Praha 7, which is a legal follower of GeoMedia.

July 31, 1999

Jan Hollan, N. Copernicus Observatory and Planetarium in Brno