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Old 04-17-21, 03:39 AM   #1
Pilot_76
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Icon14 Get your Celestial Navigation Almanac for SH +Pub 229.

Greetings fellow Skippers.

Sh4navpkg.zip by 6SJ7GT / Mike and Stellarium have given us the chance of actually replicating Celestial Navigation in SH series (SH 3-4-5 if I am right) by using a Python script and obtaining the actual Sub position and transferring that into Stellarium. From there you would simply see the same sky that the game would be showing. Then the real work of sight reduction would take place.
EzAlmanac Celestial Navigation app for the iOS (https://www.ezcelestial.com/) has reached the end of its life cycle and no further support is available as of now. The focus now is its replacement, “ezAlmanac One”. An Android version is about to be released soon as well. The good thing about the old version is that it has an “Easter Egg” that allows sights to be taken before January 1st, 1960. The newest version as far as I know does not let any sights to be taken before this date. So before Apple comes up with a new iOS update and renders ezAlmanac “unloadable” forever, I came up with the idea of taking advantage of this “Easter Egg” and print out Pub/H.O. 229 tables for the period of War Patrols from the game. SH3 starts as early as August 1st, 1939 so to cover SH 3-4-5 I’ve printed out Nautical Almanac Daily Pages covering August 1st, 1939 to December 31st, 1945. The format of these tables is familiar for those who use the modern Nautical Almanac published by USNO. These pages have additional data as well such as “Equinox Time”, “v or d” and others just like a modern almanac.
The files were organized by year and each “zip” file contains the necessary tables for sight reduction. These include:

• Nautical Almanac Daily Pages.
• Altitude Correction Tables 10°-90° and 0°-10° for Sun, Stars and Planets.
• Altitude Correction Tables for 0°-35° and 35°-90° for the Moon.
• Additional Correction Tables (Refraction).
• Index to selected Stars by year.
• Tables for interpolating Sunrise, Moonrise, etc.
• Conversion of Arc to Time.
• Sun’s True Bearing from Sunrise to Sunset.
• Polaris (Pole Star) Tables for each year.

Please note that for any dates prior to January 1st, 1940 the only data that I could access were the Nautical Almanac Daily Pages. So that is the only thing that will be available from August 1st-December 31st, 1939. Altitude Correction Tables, Index and especially Polaris tables were not accessible (coding with old data etc). A2 tables from 1940 might be useful, but I haven’t tested to see the error that it might cause in obtaining Ha. Another issue was that for Daily Pages of 1939 I had to print page per page manually. Hence, the many PDF files. I tried to merge them all into a single PDF but for some strange reason my PDF software came up cutting edges and zooming in and totally ruining everything. On-line merging pdf webpages did not allow me to read the whole file’s name, so I would have to rename the whole thing in numbers and I got lazy. Feel free to organize yourself the way it’ll suit you best. Thankfully it’s just the last quarter of ‘39. A small issue that I also noticed was that in the 1939 Daily Pages the “Equinox Times” numbers are useless.
Possible workarounds to get the additional corrections for a more precise Ha for that period:

1) Use Celestial Navigation spreadsheets (xls files at http://www.navigation-spreadsheets.com/) or any other PC/App that can be set to 1939. Corrections will be there. The drawback is that you must use a spreadsheet in 1939. A bit unusual for that time!

2) Cheating. Yes, you heard me. But just a bit. Since Stellarium will give you the correct location you may change the DATE in Stellarium to any other date starting from January 1st, 1940 to December 31st, 1945 because all the tables will be there. Including A2 and Polaris’ tables.

To learn Celestial Navigation I suggest the following:

Celestial Navigation for the Clueless by Jeremy Bernal.
Celestial Navigation in the GPS Age by John Karl.
Any books by David Burch.
Celestial Navigation by Tom Cunliffe.
Celestial Navigation in a Nutshell by Hewitt Schelereth.
Astro Navigation Demystified by Jack Case
Celestial Navigation for Yachtsmen by Mary Blewitt.

Those books are not in a particular order of importance but reading them all is a must.
http://thenauticalalmanac.com/ has tons of material and free NA. Also, HO 229/249 tables as well. Tutorials and forms for sight reductions too. A big thanks to the EzAlmanac team for an outstanding app. I strongly suggest getting EzAlmanac One. Happy hunting!


Pilot_76.

https://drive.google.com/drive/folde...7G?usp=sharing
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Old 04-17-21, 09:15 AM   #2
FUBAR295
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Icon14

Great post.

I was interested in getting into celestial navigation and collecting material to assist in that endeavor. This will help immensely.

Good hunting,
FUBAR295
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Old 04-17-21, 12:51 PM   #3
Pilot_76
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Quote:
Originally Posted by FUBAR295 View Post
Great post.

I was interested in getting into celestial navigation and collecting material to assist in that endeavor. This will help immensely.

Good hunting,
FUBAR295

The Python script needs updating. [emoji3064]


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