|Re: Programming astronomical data ( are you with me Hrast? )|
Message #8 Posted by Antoine M. Couëtte (France) on 15 June 2004, 4:58 a.m.,
in response to message #7 by Karl Schneider
June 15, 2004
Hello to you all,
Michel, all the advice and recommendations hereabove in this thread are very clever and sound. All seem realistic solutions within reasonable reach timewise.
Just let me add 2 more options which I will be glad to discuss with you in particular if you so desire.
I would encourage you to take a look at a wonderful, concise, and very clever HP41 program written by Dr Paul Schlyter and named " PUT THE SOLAR SYSTEM IN YOUR POCKET ".
Probably Dr Paul Schlyter ( firstname.lastname@example.org ) can provide you with a copy. If he is unable to do so - and as this program was earlier published in PPC USA some 20 years ago - I can dig out my PPC files and burn a copy to you. ( By the way, can anybody confirm me that it is "legal" since I certainly do not want to infringe anybody's copyright ), unless this program is already available in some archive file ( Again: help needed here please ) .
" PUT THE SOLAR SYSTEM IN YOUR POCKET “ computes the positions of Sun + Moon + 7 main planets. Any other planet / or comet can be easily added on. From program structure, I think that any other celestial body ( star or Messier object ) can be easily added on, at the expense of some additional ( and probably limited ) programming instructions.
For your own use, PUT THE SOLAR SYSTEM IN YOUR POCKET “ computes bodies coordinates in either heliocentric/ecliptic, or geocentric/equatorial, or geocentric/local ( i.e. height and azimuth) reference frames.
In the version I have- very slightly modified for my own use from the original one - Minimum Size to run this program is SIZE 092 with registers 00 to 19 used for computations and registers 20 to 91 used for planetary data. And 2 programs are required, one with 753 bytes and the other one with 350 bytes. It means that you need to commit a total of 250 memory registers to this software, leaving you with 69 registers for other use, including fine tuning this software to your needs.
Accuracies on geocentric coordinates now: in the time frame 1900-2100 I have found that " PUT THE SOLAR SYSTEM IN YOUR POCKET “ gives the following results at 3 sigma - i.e. 99.5 % of the time –
• SUN: +/- 1.5 arc minute around true value
• MOON: +/- 6.0 arc minutes around true value
• MERCURY and VENUS: +/- 1.5 arc minute around true value
• MARS, JUPITER, SATURN, URANUS, NEPTUNE: +/- 3.0 arc minutes around true value
• PLUTO (not included in the original software and I have included it at the expense of 7 additionnal data registers so my own version requires SIZE 099): +/- 15.0 arc minutes around true value with the “ osculatory elements ” I am using. Here one can do certainly much better with better - but time limited - osculatory elements.
As regards accuracy over time frame validity , this is by far the best trade-off between accuracy over program size I ever found for the plain HP41CX. You most probably will not find any equivalent anywhere else. This is why in my opinion " PUT THE SOLAR SYSTEM IN YOUR POCKET “ is one unequalled master piece and I never miss an opportunity to praise and advocate it.
For your information, accuracies delivered by " PUT THE SOLAR SYSTEM IN YOUR POCKET “ are definitely insufficient for celestial navigation for which it has been customary to use data accurate to +/- 6 arc seconds. Such accuracies require over 50.000 bytes, so you can guess that in this range a significant increase in accuracy is achieved at the expense of a very important increase in size.
As you do require a “ hand held “ solution, and if you own an HP48GX with additional memory cards ( One 128k + I think another 128k at the minimum for the full non free version), or an HP49G - and subject to confirmation an HP49G+ - I would strongly encourage you to take a very close look at Hrastprogrammer HP41X/Z Emulator. (Are you with me Hrast?)
One version is free on the web and it can emulate a plain HP41CX.
These emulators are absolutely fantastic!!! For most if not all my applications they run 3 times faster than the standard HP41CX. And I almost totally stopped using my HP41’s when I purchased my own custom made version.
Standard non free version will give you 680 Extended Memory Free registers, 3292 Program/Data registers + 8 times 4K blocks for your own programming needs! It is over 20 times the standard program space of the HP41CX with over 95% of it protected from MEMORY LOST! And you can also choose to allocate any HP41 module into these 4K blocks, including the NAVIGATION Module, thus leaving you with the option of following one of the advices given you hereabove in this thread!
For more details, go to http://hrastprogrammer.tripod.com/ and if you want to directly contact Hrast, let me know.
You may also have a look at the following HP Forum thread:
Hope all this information is useful to you.
Best Regards from Antoine M. “ Kermit” Couëtte
+33-(0)612 88 06 36