ASTRONOMICAL-CELESTIAL NAVIGATION

[PedroLeiva]

Reference: HP67/97 NAV PAC I
A practical program for position location of a vessel in the sea will be to get LAT and LONG observing the sun or moon having the following data: sextant angle, date&hour, star constants, etc.
Does somebody has experience in this issue to explain me the steps to follow to get this information? In NAV PAC I there are many programs, but I do not know how to apply them. Or better jet, does somebody have (or know about) a program for HP67 to make this calculations.

It is important to remember that in 15th century navigators used this system with success, but today pocket calculators takes care of solving the formulas, a time consuming process.

Any information will be welcome. Pedro

[Maximilian Hohmann]

Hello!

(01-22-2022 03:07 PM)PedroLeiva Wrote:  It is important to remember that in 15th century navigators used this system with success,...

Not really, because as you write above, one of the key inputs for celestial navigation is the (exact) time. It is required to determine one's longitude and the difficulties associated with that were known as the "longitude problem" for centuries (https://en.wikipedia.org/wiki/History_of_longitude). It was only solved in the 18th century when Harrison developed the first properly working ship chronometer.

The subject of celestial navigation is rather complex for a forum post. I would suggest to look at a book on the topic (e.g. „Celestial Navigation with a Pocket Calculator“ by Jonah Slocum - but there are several others!) or one of the many websites that deal with it. I also found the (rather compact) user manual that comes with the Tamaya NC-77 calculator to be a good introduction to the subject.

And be aware that in order to do celestial navigation with the pocket calculator you will also need a current copy of the „Nautical Almanac“ which is pulished new every year. This book has the size and mass of telephone directory of a large town... You can of course use an app on your cellphone or tablet to do the almanac calculations for you but that obviously takes the fun out of using your HP-67 for it :-)

Regards
Max

[PedroLeiva]

Yes, the LONG problem was not solve by correctly calculating the time factor, but anyway they travel using the stars as references. Pedro

[Maximilian Hohmann]

(01-22-2022 05:38 PM)PedroLeiva Wrote:  ... but anyway they travel using the stars as references.

Yes, sure. But this kind of celestial navigation (using the sun or non-moving stars like the North Star for direction finding) can not be performed with a pocket calculator.

[PedroLeiva]

I have a lot to learn on the subject before I can obtain the geographical position by looking at the stars, as the crew members of the Atlantis Expedition did in 1984. Pedro

[Maximilian Hohmann]

Hello!

(01-22-2022 07:36 PM)PedroLeiva Wrote:  I have a lot to learn on the subject before I can obtain the geographical position by looking at the stars, as the crew members of the Atlantis Expedition did in 1984. Pedro

They had a full 52 days with not much else to do to figure out how celestial navigation works, while their raft drifted across the Atlantic Ocean :-)

Here I found a comprehensive (yet with 100 pages not overly long) book downloadable from the internet: http://www.dacust.com/navigation/pdf/Arm...igator.pdf

On pages 87 and 88 you can find a summary of the equations that will need to be programmed into your calculator - or calculated on the spot using paper and pencil as a ship's navigator would have done in the year 1800.

Regards
Max

[PedroLeiva]

Hi Maximilian. This is just what I was looking for. The 4 basic navigation tools (sextant, nautical almanac, calculator and chronometer), data tables to complete and formulas to calculate. It seems to work as an understandable system: INPUT --> OUTPUT, very clear and straightforward, just right for programming calculations on my HP67.

Also in Appendix 2 "Making Your Very Own Octant", that is great, TYVM. Pedro