Eclipse Path - 14 December 2020 Map
Created By: kirkw3
Last Updated: December 1st, 2020 11:12pm
West: -132.875° East: 11°
Country: Argentina, Chile
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This map is a transparent overlay of the path of the total solar eclipse of December 14, 2020, which will pass across the southeastern Pacific Ocean, Chile, Argentina, and the southern Atlantic Ocean. It shows closely calculated estimates of the centerline, north boundary, and south boundary of the path of totality. This overlay is intended to be displayed on Garmin devices on top of a user's ordinary map and will show the eclipse path with respect to the cities, highways, and landmarks depicted in the ordinary map.
Feel free to use this map and to pass it on to other people, but please read and pass along this disclaimer, too:
NOTICE: This eclipse path map is a close approximation but is NOT exact.
While subject to possible variations of several tens or hundreds of meters, this map should ensure that someone reasonably inside the displayed eclipse path should be able to witness totality. This map for Garmin devices was compiled based on eclipse boundary points computed at longitude intervals of 7.5 minutes by David Herald's astronomical occultation prediction program Occult 220.127.116.11. Astronomical data used with this version of Occult 4 was updated as of October 24, 2020. The updated data and closely spaced data points should enhance the accuracy of the map's predictions. However, it cannot be precise. This map has been compared and spot checked with data published by NASA/GSFC's Fred Espenak and has been found to track the curves from that data closely and consistently, although not identically.
Specifically, the eclipse tracks on this map lie about 100 to 200 meters south of those predicted by Espenak over land in South America and slightly farther south than that in the Atlantic. In the southeastern Pacific near the beginning of the shadow path, the tracks lie a similar distance north of those predicted by Espenak, with the disparity increasing to 400 to 2100 meters where the tracks first begin.
In general, various astronomical sources incorporate slightly different eclipse elements into their calculations, which will result in slight differences in predicted eclipse path boundary lines. Also be aware that the map's curves were interpolated from a finite collection of fixed points and that rounding or compression errors may occur during the compilation of the map. More importantly, the curves of this map do not take into account the irregular, mountainous edge of the moon. These lunar irregularities may shift the eclipse's shadow on earth by up to 1 to 3 km (0.6 to 1.9 miles) north or south. All of these factors are significant to viewers situated near the edge of the path. Those users are advised to consider the north and south limit lines as approximate when viewed at high zoom levels. Viewers should NOT use the curves of this map to position themselves at the precise edge boundaries of the eclipse path. This map's accuracy is not sufficient. Instead, those people wishing to do so should consult an accurate scientific reference just prior to the time of the eclipse.
Also included as a separate file is a GPX file of the path of the centerline only. This track file was created from the same Occult 4 data and is subject to the same accuracy limitations.
To use this map, copy the file "eclipsepath14dec2020.img" to the "Garmin" folder on the removable SD card in the Garmin GPS device. It should also be possible to copy the file to the "Garmin" folder in the device's internal memory provided the file does not share the same name as any other existing file. If you have installed a previous or different version of this map, first delete the old IMG file, as the two maps have the same map ID and cannot coexist. Exercise caution not to overwrite, move, or delete any other files or folders when installing this map. When finished, disconnect the GPS device from the computer if applicable. Then turn on the device normally and go to the start or menu screen. On many devices, go to the "Setup" menu and select the "Map" and then "Map Information/Select Map" options. Two or more different maps can be displayed simultaneously on modern devices; on the list of available maps, ensure that "Eclipse Path" and a general map of the area of interest are both enabled. (This may be done on certain devices by tapping the map name and then choosing "Enable.") Return to the main menu and view the map. The eclipse path will be superimposed on the other map. It may be desirable to zoom outward when first viewing the eclipse map before zooming in to an area of interest. (The above procedure was tested successfully on an Oregon 200.)
NOTE TO NUVI USERS: A user reported that he was unable to display an eclipse map of this series on his Nuvi device after following the above instructions. The author has confirmed this issue on a Nuvi 350 (Software ver 6.10). It may be possible to display the eclipse map on this and similar Nuvi devices by following an alternative procedure. Read the text file "Readme_eclipse_path_instructions_14dec2020.txt" which is included in the zip file that can be downloaded from this web page. Refer to the Nuvi instructions in that file. This procedure was successful on the above-mentioned Nuvi 350. Be aware that the procedure is straightforward but intended for experienced computer users and that users take the risk of potentially disabling their Nuvi device's functionality. Nuvi users voluntarily follow the steps at their own risk and the author assumes no responsibility for any resulting damages. See zip file for specific instructions.
This eclipse path map was created and compiled by GPS File Depot member kirkw3 from data generated by David Herald's Occult 4 occultation prediction astronomy program, version 18.104.22.168. Ephemeris DE438 and program-estimated deltaT=69.13 were incorporated into the program's computations. Data was parsed and organized with custom-written software and splitter-r597 and compiled with mkgmap-r4588 on November 21, 2020. The GPX file was generated on November 21, 2020. While believed to be accurate within the described limitations, the author assumes no responsibility for this map file's use/misuse or any consequential damages.
This map was posted on GPSFileDepot.com on December 01, 2020. The URL links in the text above were valid on December 01, 2020.
Changes: Dec. 01, 2020 New map posted to GPSFileDepot.com.
Dec. 01, 2020 Instructions updated to reflect correct GPS File Depot map number (847).
Dec. 02, 2020 Minor text correction to read "southeastern Pacific".
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