    This map is a transparent overlay of the path of the total solar eclipse of December 04, 2021, which will pass across the South Orkney Islands and Antarctica.  It shows 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 land areas 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.

    This map for Garmin devices should ensure that someone reasonably inside the displayed eclipse path should be able to witness totality.  This map was compiled based on eclipse boundary points calculated by David Herald's astronomical occultation prediction program Occult 4.12.15.7.  A small number of additional boundary points were provided by Fred Espenak and NASA's GSFC.  Astronomical data used with Occult 4 was updated on November 14, 2021.  The updated data should enhance the accuracy of the map's predictions.  However, it cannot be precise.  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.  In addition, the map's curves were interpolated from a finite collection of fixed points and 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.  Note that the user's map must be capable of displaying the continent of Antarctica in order to view the complete path.

    Path coordinate data was taken from three sources.  While other eclipse maps in this series are based completely on closely-spaced data points from Occult 4's Path Coordinate generator, this feature generates incomplete data for high-latitude solar eclipses in which the track falls beyond the pole and in which the track therefore travels westward for part of its path.  For the westward-travelling portion of the path, an Occult 4-generated KML file with fewer data points of the complete track was used and converted losslessly to OSM format before compilation.  Because Occult 4 calculates data points in discrete steps of longitude, portions of the eclipse path which travel north-south with little change in longitude are depicted with poor resolution.  The path appears clipped or as a straight line in those areas.  For this reason, Fred Espenak/NASA GSFC data was incorporated to more accurately present the eclipse path in those locations.

    To use this map, copy the file "eclipsepath04dec2021.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.  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.

NUVI MAP INSTALLATION INSTRUCTIONS:  These instructions were tested successfully on a Nuvi 350 running software version 6.10 interfaced to a Windows 7 laptop.  This may work on similar devices but this has not been tested.  Users proceed at their own risk.

Turn on the Garmin Nuvi device and allow it to boot up.  Use a USB to USB MINI (on many units it is NOT the more common USB micro plug!) cable to connect the Nuvi device to a PC running a modern version of Windows.  The computer should recognize the Nuvi as an external drive and assign it a drive letter.  The drive may be named "Garmin nuvi".  The PC may prompt the user "Do you want to scan and fix Garmin nuvi?"  If this message appears, do NOT scan and fix.  Instead, click "Continue without scanning".  Open the folder to view files.  Various folders and a few files on the Garmin Nuvi should be visible.  Look for and open the folder named "Garmin".  In the "Garmin" folder should be several files that begin with the letters "gmap".  If a file with the exact name "gmapsupp.img" is already present, copy that file to another drive such as the main computer hard drive or to a flash drive.  If any other files beginning with the exact letters "gmapsupp." exist, back up those as well.  Be certain to perform this backup so that the existing map can be reinstalled on the Nuvi device in the future and used again.  Once "gmapsupp.img" and any other "gmapsupp." files have been copied and backed up, delete those files on the Garmin Nuvi device.  Be absolutely certain not to delete or move any other file, folder, or files.  Take special care not to delete any other "gmap" files that have slightly different names than "supp" (those are your main maps!).  If the file "gmapsupp.img" was not originally present, do not make any deletions.

Find the file "eclipsepath04dec2021.img" on the main computer.  Rename the file "gmapsupp.img".  After that, copy that renamed "gmapsupp.img" file to the "Garmin" folder on the Nuvi device.  Be sure to rename the file to "gmapsupp.img" before copying it to the Nuvi device.

In the main taskbar at the bottom of the main PC computer screen, find and click the icon to "Safely remove hardware."  Click "Eject Garmin nuvi".  Alternatively, in Windows Explorer, right click on the "Garmin nuvi" drive and choose "Eject".  If a message appears informing the user that the "Garmin nuvi" drive is currently in use, click "Cancel" and check that no files on the Garmin nuvi have been opened.  (This should not be the case if these instructions have been followed correctly.)  It may be necessary to close any such applications, including Windows Explorer.

Once the Garmin Nuvi has been ejected from the PC, a message stating "An error occurred while ejecting Garmin nuvi" may appear.  If it does, click OK.  Then unplug the MINI USB plug from the Garmin Nuvi device.

Verify eclipse map installation by touching "settings" on the Nuvi device's main screen.  Then touch "Map" and then touch "Map Info" at the bottom of the Nuvi's screen.  The Map Info screen should show the eclipse path map's title in addition to the title of the main user map.  Be sure both maps have their boxes checked.

Go back to the main Nuvi screen and touch "View Map".  Move or scroll the map until the area of interest is visible.  (It may be necessary to zoom out.)  A slowly curving set of three lines delineating the eclipse path should be visible on top of the ordinary map.


    This eclipse path map was created and compiled by GPSFileDepot member kirkw3 (Kirk Wines, kirkw3@yahoo.com) from data calculated by David Herald's Occult 4 occultation prediction astronomy program, version 4.12.15.7 along with a small number of data points from Fred Espenak and NASA GSFC's prediction.  Ephemeris DE441 and program-estimated deltaT=69.50 were incorporated into Occult 4.12.15.7's computations.  Data was parsed and organized manually and with Notepad++ v.6.7.7 and MapEdit++ ver. 1.0.61.496, then complied with splitter-r597 and mkgmap-r4588 on November 17, 2021.  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 November 18, 2021 and can be accessed at https://www.gpsfiledepot.com/maps/view/865.

    See the following resources:

https://eclipse.gsfc.nasa.gov/SEpath/SEpath2001/SE2021Dec04Tpath.html  (Table of Fred Espenak's eclipse path predictions)

https://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2021Dec04Tgoogle.html  (Interactive Google map of the above predictions)

King, B. (2021, December). Celestial Calendar. Sky and Telescope, 142(6), 50.

David Herald's Occult 4 occultation prediction software can be obtained at http://www.lunar-occultations.com/iota/occult4.htm

    The above URL links were valid on November 18, 2021.


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Changes:  November 18, 2021  New map posted to GPSFileDepot.com at https://www.gpsfiledepot.com/maps/view/865
