Many thanks to SWLing Post contributor, Nick Hall-Patch, who shares the
  following article originally published in the IRCA’s DX Monitor:
    __________________________________________________________________

  by William Scott, WE7W

  DXing the mediumwaves promises to be an exciting event on April 8
  during the 2024 total solar eclipse. I’ve been mulling over the DX
  possibilities a lot lately and have come to some conclusions. I think
  it boils down to three promising DX scenarios:
    * Scenario 1. For those who live within or very near the path of
      totality (see Figure 1), I believe best chances of DX would be
      first to listen to your southwest, along the path where totality is
      approaching. Darkness will already have happened in that direction,
      and a certain amount of residual de-ionization of the ionosphere
      will still remain. After the point of totality passes your
      location, I would swing my attention to the northeast.

    * Scenario 2. For those living within about 800 km (or about 500
      miles) of the path of totality I believe best chance would be a
      perpendicular path across the totality path to a point roughly
      equidistant on the other side. This puts the signal reflection
      point right at the center of the totality path, or the deepest
      point of darkness.

    * Scenario 3. For those living more than about 800 km from the path
      of totality I believe best chance would be along a line from your
      receiving site to a perpendicular intersection to the totality
      path. This should define the greatest shaded path.

  I think that scenarios #1 and #2 have the best possibility for DX.

  Figure 1 (Click to enlarge)

  Across the U.S. and Canada, from its entry at Texas to its exit through
  NE Canada and into the Atlantic Ocean, the totality path width varies
  from a maximum of 199 km at U.S. entry to about 160 km at Atlantic
  exit, or 123 to 99 miles.

  Important to keep in mind – skywave signal strength analysis is based
  almost entirely on the condition of the ionosphere at the reflection
  point, not at the receiving site. For single hop propagation, normally
  the reflection point is at the halfway point to the station along the
  great circle route. That 800 km distance from the totality center I
  wouldn’t hold as gospel. I’m throwing that figure out as a point where
  scenario #2 may start to transition to scenario #3.

  Timing is of the essence for DXing. The shadow velocity exceeds 1000
  mph, increasing from 1587 miles per hour at Eagle Pass, Texas to 3176
  mph at Houlton, Maine. You may have only minutes to DX. I’ll be in
  Rochester, NY at the time of totality, and we are right at dead center.
  I’ll be scenario #1. My plan is to listen to my southwest initially,
  where totality is approaching. I’ll be listening particularly for
  WLW-800 in Cincinnati, OH, WHAS-840 in Lexington, KY, and others along
  or near that path.

  Scenario #2 possibly holds the most promise. Calculate your distance to
  the path center line and look for stations on a direct line across the
  totality path and at an equal distance on the opposite side of the path
  from you. One such scenario might be WSB-750, Atlanta to a reception
  point in northwestern Illinois, central Iowa, or southern Wisconsin or
  southern Minnesota. Many possibilities on cross-paths exist here. I
  feel best results would be with a signal path that crosses the path of
  totality closest to 90 degrees.

  A question was raised about the possibility of DX from Spokane,
  Washington, an extreme distance from the path of totality. That
  particular scenario would be scenario #3, more than 800 km to the path
  of totality. Maximum obscurity should be when northeast Texas (let’s
  say the Dallas area) is experiencing full totality, as the great circle
  line to the totality path intersects at approximately 90 degrees to the
  line at that point. This would be at about 1848 UTC. I would listen for
  any signals along a great circle path between Spokane to anywhere from
  the Dallas area and northward. Obviously, Spokane to Dallas is an
  extremely long one hop path, at about 2450 km. At that distance, the
  reflection point is near Denver, which will have a solar obscuration of
  65.1% at maximum.

  A Dallas area reception would be next to impossible I would think, but
  there are many more stations along that great circle path one could try
  for. Closer stations will obviously move the reflection point closer
  and start to reduce the solar obscurity. I did a scan along that path
  and there are some 340 stations within 200 km either side of the line
  of the great circle path between Spokane and Dallas.

  A presumed Scenario #4.

  Another scenario was suggested by Nick Hall-Patch, that of reception
  parallel to the path of totality and outside the 100% totality band.
  The 2017 solar eclipse across the northern part of the U.S. was DXed
  extensively and produced some interesting results, which are well
  documented in IRCA Reprints. Check their document repository here:

  [1]http://dxer.ca/images/stories/2019/irca-reprint-index.pdf

  Nick reports: “The receptions of KSL-1160 described in IRCA Reprint
  [2]# G-096 showed the results of 3 DXers listening across the path of
  the eclipse (Scenario #2), but the fourth, Dave Aichelman, was
  monitoring KSL from a location parallel to the eclipse path ( sort of
  Scenario #1?) and got very good enhancement as well.” We might name
  this “Scenario #4”.

  I checked out [3]# G-096, that documents the KSL reception from the
  solar eclipse of 2017. It looks like the Dave Aichelman (at Grants
  Pass, OR) reception of KSL had a mid-path reflection point of about 95%
  solar obscurity. The distance was 971 km (602 miles). Graphing KSL, I
  see it has a nice fat low angle takeoff and impressive skywave strength
  at 900 km, some 1.3 mV/m for that distance. (ed. note: A map of
  fractional solar obscuration is in Figure 2, easily converted to the
  percentage figures quoted in this article. )

  Better yet, the article indicated Aichelman also received XEPE-1700
  across the Mexican border from San Diego too. That was a mid-point
  reflection obscurity of only about 83% as far as I can deduct from the
  maps. The distance was 1238 km (769 miles). The mid-path reflection
  point there was in the neighborhood of 700 km from the central path of
  totality.

  So, DX is indeed possible where both the station and the receiver are
  off center from the totality path. It’s looking like anything from at
  least 80% obscurity at mid-path reflection may have some real
  possibilities, particularly if you are at the end nearest the path of
  totality. Lower obscurities, perhaps down to 50% or so may even produce
  results.

  Check out these links.

  [4]https://nationaleclipse.com/cities_partial.html

  [5]https://eclipse.gsfc.nasa.gov/SEpath/SEpath2001/SE2024Apr08Tpath.htm
  l

  [6]https://eclipse2024.org/eclipse_cities/statemap.html

  Using my pattern mapping program which has extensive area search
  capability, I’ve compiled a list of all US and Canadian stations that
  fall within the 2024 Solar Eclipse path of ~100% totality. There are
  456 stations. Results are drawn from the March 20 FCC LMS database and
  Industry Canada database. Sorry I don’t have Mexico available.

  If you would like this list, download from this link.
  [7]https://www.mediafire.com/file/125ih5yrmw4puib/2024-eclipse-stations
  -by-longitude.zip/file

  Across the US and Canada, from its entry at Texas to its exit through
  NE Canada and into the Atlantic Ocean, the totality path width varies
  from a maximum of 199 km at US entry to about 160 km at the Atlantic
  exit off Newfoundland, or 123 to 99 miles. 456 stations are found in
  this eclipse path. I purposely set the path width to 210 km from start
  to finish. This gives a few km slop on both sides of the 100% totality
  path for good measure.

  Unzip the downloaded .ZIP file, where you will find 3 files. The
  stations in each file are sorted by longitude, from west to east. This
  gives us the progression of the eclipse path, with the eclipse starting
  at the first station in the list and ending with the last station.

  File #1 is a simple text file.

  File #2 is in .CSV format. You can easily input it to an Excel file.

  File #3 is in .HTML format. It includes links to each station’s Google
  Map latitude-longitude coordinates for the satellite view of the
  transmitter tower array.

  Another link takes you to the FCC AM Query link for that station. I
  hope these files are beneficial. There should be many propagation path
  possibilities outside of this list as well.

  (reprinted from the author’s blog at
  [8]https://radio-timetraveller.blogspot.com/ )

  ********

  Further sources of information concerning the eclipse include the
  following websites:

  [9]http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2024_GoogleM
  apFull.html?Lat=43.66400&Lng=-76.13690&Elv=88.0&Zoom=6&LC=1

  (Clicking anywhere on this map page will give all the information you
  need about obscuration, length of eclipse etc.at a given location).
  Also:

  [10]https://www.greatamericaneclipse.com/april-8-2024

  [11]https://eclipsewise.com/2024/2024.html

  Animations of the path of the eclipse versus time can be seen at:

  [12]https://eclipsewise.com/solar/SEanim400/2024_04_08_TSE_400px.gif

  [13]http://7dxr.com/4all/100km8Apr-movie–Frissell-HamSCI.mp4

  The latter is particularly interesting, as it shows the moon’s shadow
  at 100km height above the earth, an area of special interest to DXers,
  as it is the lower edge of the E-region of the ionosphere. Note
  especially that as the eclipse ends over the North Atlantic Ocean, that
  there is a temporary darkness path between Europe and North America,
  because night will already have fallen in Europe. So will there be
  blips of TA DX in eastern North America as the eclipse passes by?
  Listen, and find out!

  Finally, our DX could be of interest to ionospheric physicists also.
  The rapidly changing listening conditions will be indicating a
  similarly turbulent ionosphere, and DXers’ documenting those listening
  conditions through SDR recordings could provide information that will
  be useful to scientists who want to gain a better understanding of the
  Earth’s ionospheric dynamics.

  HamSCI is an organization of volunteer citizen-scientists and
  professional researchers who study upper atmospheric and space physics,
  and will be interested in examining MW DXers’ wideband SDR recordings
  made during the eclipse period, and indeed, in having DXers assist with
  HamSCI’s research. (see [14]https://hamsci.org/eclipse. Especially if
  you are an amateur radio operator, there are several other ways that
  you might also contribute to the project.)

  (This first appeared in IRCA’s DX Monitor and is used with permission.
  See [15]https://www.ircaonline.org/default.php for club details)

References

  Visible links:
  1. http://dxer.ca/images/stories/2019/irca-reprint-index.pdf
  2. https://drive.google.com/file/d/1AMJtjcRMjq09oqmuLhrBq5urlTQIVoGs/view?usp=sharing
  3. https://drive.google.com/file/d/1AMJtjcRMjq09oqmuLhrBq5urlTQIVoGs/view?usp=sharing
  4. https://nationaleclipse.com/cities_partial.html
  5. https://eclipse.gsfc.nasa.gov/SEpath/SEpath2001/SE2024Apr08Tpath.html
  6. https://eclipse2024.org/eclipse_cities/statemap.html
  7. https://www.mediafire.com/file/125ih5yrmw4puib/2024-eclipse-stations-by-longitude.zip/file
  8. https://radio-timetraveller.blogspot.com/
  9. http://xjubier.free.fr/en/site_pages/solar_eclipses/TSE_2024_GoogleMapFull.html?Lat=43.66400&Lng=-76.13690&Elv=88.0&Zoom=6&LC=1
 10. https://www.greatamericaneclipse.com/april-8-2024
 11. https://eclipsewise.com/2024/2024.html
 12. https://eclipsewise.com/solar/SEanim400/2024_04_08_TSE_400px.gif
 13. http://7dxr.com/4all/100km8Apr-movie--Frissell-HamSCI.mp4
 14. https://hamsci.org/eclipse
 15. https://www.ircaonline.org/default.php

  Hidden links:
 17. https://swling.com/blog/wp-content/uploads/2023/02/spectrum-with-1886-flat.jpg
 18. https://swling.com/blog/wp-content/uploads/2024/04/Eclipse-Figures-1.jpeg
 19. https://swling.com/blog/wp-content/uploads/2024/04/Eclipse-Figures-2.jpeg

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