Astro-nav. software

[Gazza]

Am thinking of automating the calculation stage of astro-nav. - has anyone any experience of PC software for this application? I'm looking at an advertisement for PC Sightmaster by Dolphin Software, but any other options gratefully considered.

 

[HaraldS]

If you have Excell on your PC, I can send you the one that I made a few years ago when I took a deep dive into celestial mechanics for fun.

It also substitutes the Almanac and gets as close in precision as you can possibly, given that some things like speed of earth rotation aren't fully predictable.
It gives you a page where you can enter time sexatant reading etc. including an assumed position. It will then give you the usual azimuth and intercept from there. If the position is taken from the GPS, the intercept is how far off you are with sextant.

It also sorts the visible stars from your assumed postion by azimuth, and gives you the calculated altitute, so you can preset the sextant and it's easier to identify them. Finllay you get all the interseting data like rise and set of sun, moon and planets, moonphase and all the other relevant data for the various bodies.

Just drop me a note if you want it, and an e-mail address and I'd be happy to mail it.

<A target="_blank" HREF=http://www.taniwani.de>http://www.taniwani.de</A>

 

[FlyingSpud]

Why?
I mean, if your going to let a computer do all of the work anyway, why not use a GPS? Surely the whole point about astro is the fun and challenge (and backup) of doing it without electronics. If you are doing a long crossing, there’s plenty of time.

 

[Guest]

Why? Why? Flying Spud

Can't you just help if you can?

Why Gazza wants some software is his business.

For all you know he wants the software to help him check practice sights while developing his sextant skills, which is exactly why I asked the same question at the rather more friendly GPS-Navigators yahoo-group. I got useful and helpfull information rather than shallow criticism of my motives.

Gazza, try www.pangolin.co.nz for a trial version of their package. It seems to work very well.

Also useful if you want to shoot some sights without buying the rip-off Britain HMSO Nautical Almanac, the following site will give you almanac details for any day and any place: www.usno.navy.mil/data/docs/celnavtable.html free of charge.

 

[snowleopard]

would be very interested to find out the algorithms you used. i tried to work it out from scratch using astronomy textbooks but got bogged down.

i tried posting the request on ybw but all i got was a load of people telling me i shouldn't be doing it. (i'm a professional programmer and wanted an interesting challenge)

 

[HaraldS]

Hi Snowleopard!

If you send me a PM with your e-mail, I'll send it to you. Dig through the sheet called "MAIN" to see the algorythms, lots of comments. Some sheets are locked against accidental modification, but no password on them, so just unlock. There is also a sheet with version history that will explain what I went through to make it more and more accurate, way beyond sextant. Some of the more complex stuff for correting moon and planetary perturbations on the earth, I got from official JPL Fortran programs.

I have also made some simple ones sharp scientific calculators, that do just the earth-sun system.

<A target="_blank" HREF=http://www.taniwani.de>http://www.taniwani.de</A>

 

[bedouin]

I'm half-way through an Excel spreadsheet to do the same thing. You get a much better understanding of the concepts involved by doing it that way.

The big practical benefit is that it removes the need for an Almanac - which is a considerable expense if you don't use it "in anger"

I'd be interested to see your spreadsheet - I'll PM an email address

 

[alex_rogers]

Have a look at the site below. The calculations are simplified but still provide better than 1 minute accuracy. Lots of explanation as well.

http://hem.passagen.se/pausch/comp/ppcomp.html


Alex Rogers
<A target="_blank" HREF=http://www.YachtsAtSea.com> www.YachtsAtSea.com </A>

 

[FlyingSpud]

Re: Why? Why? Flying Spud

See the squiggle after the word ‘Why’?, It’s a question mark denoting an interrogation rather than a statement.

I am asking what seems a sensible question, I think. To be more specific why does one use astro rather than GPS? I can only think of two reasons

1. Its more fun to do it, a bit like sailing is more fun than driving or taking a plane. If so, what is the point of automating the procedure? If the answer is that the only fun bit is using the sextant, then why not just use the sextant and then look at the GPS?
2. Because it’s a backup and you need to practice. The most likely scenario for this would be something like a power failure, in which case the computer will not be much use either, so you certainly can’t rely on a computer in place of the normal tables, and as to the calculations, it would be best practice without a computer.

In neither case do I see what you get out of a program. Obviously Gazza, and others who buy these programs, do and so I am asking him what.

So why the personal attack?

 

[Guest]

Re: Why? Why? Flying Spud

I am practising my sextant work every afternoon in the Florida sunshine, there are no power failures, but I do want to check the accuracy of my work and it is quite reasonable and simple to do it using a computer program, particularly as all my books are in London.

If you think my posting was a personal attack, then I hope that you never offend me (and you must have led a very sheltered life!)

 

[CPN]

Have excellent software, which runs on a Psion 5, from: www.system.co.uk
They also have an Excel Spreadsheet version for PCs, which I haven't tried.
Psion version includes an almanac., star identification program and more. Can be downloaded from Internet and then on payment of $40, one gets the key to the full program and updates of the almanac - I reckon its very good value - and I'm a tight-fisted Yorkshireman !
Have fun
Pete

 

[ponapay]

The best spread sheet I have seen ..

well done Harald. I wish there were more helpful and thoughtful people like you.

The sheet worked well on my two sun sights today. Many thanks.