Celestial Navigation: Sunset & Sunrise Calculations

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----------ABOUT THE VIDEO----------

This video was originally uploaded to our other channel, Casual Navigation, back in 2018.

Manual calculation of sunrise and sunset are one of the foundations of celestial navigation. In this video I show you how to undertake the calculations using a Nautical Almanac.

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[WyMustIGo]

Isn't the change per minute supposed to be (300 / 7) or 42.85 minutes of latitude per minute of time, and NOT 42.6?

[sv_embracelife]

Hi, just looking for some help, please. 7mins into this video it explains longitude of 073.561 divided by 15 degrees = 4.929. When I do this calculation I get 4.904. What am I doing wrong here, thank you

[Whisperin]

your interpolation is strange, proper way is 05:24 - 05: 17 = 7 min / 5 DEG = 1.4 min change every deg, then for 41= 05:24 - 1.4 min = 05 22.6 = round it to 05: 23 min

[luissantoscosta]

Finally I find an explanation, which really explains how it is done. Thanks

[evilfluff]

Why would you use New York time all the charts and tables is set up in GMT time zone and if you are using New York time just add five hours to the time like like if it is 05:00 in New York in London England (GMT) it is 10:00 so you add five hours to your clock time at the start. I think you are over working it.

[markprange]

There are a few other ways to calculate it.

The angular height of the observed Sun is just the sum of corrections [for dip, astronomical refraction, terrestrial refraction (from horizon to eye it is about -.18´ times the eye-height in feet), semidiameter, and parallax; except for parallax they are each negative]; rearrange the height formula to instead find the longitude difference between observer and Sun, and then determine the West longitude of the Sun. Interpolate in an almanac to find when the Sun will have that longitude.

Or use a convenient time and exact position, and compute a line of position.

[ضحككومسلسلاتمضحكه]

I will be...so thanks for you ... if will add the translation to Arabic language 🙄🥺

[harbourdogNL]

Now that's concise. (You must have a captive audience down the pub when folks ask you about navigation or maths!)

[clivanzsaitama]

If longitude is east all i have to do is minus the sunrise at latitude, with the time difference of longitude, is that correct?

[ضحككومسلسلاتمضحكه]

Can you please add .... moonset and moonrise

[jonathanstaley]

Great explanation! Thanks that was a huge help!

[ForDreamsThatDoComeTrue]

Thank you so much for this wonderful and absolutely amazing content and explanation...FROM INDIA/

[albertlim]

How to get the 42.6
When it comes the
5√7?

[captainphil]

The purpose of the sunrise/set amplitude is compass correction. It's a way to check the accuracy of your magnetic or gyro compass. This is only the first half of the calculations. After this you must work out the azimuth bearing of the set/rise and compare that to your observation, (you usually use the gyro repeater on the bridge wing).

[albertlim]

How to get the 42.6
When it comes the
5√7?

[clivanzsaitama]

Plane and simple, can you do celestial observation about LOP