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    Re: HP 48GX Sight Reduction Programs
    From: Aubrey O´Callaghan
    Date: 2001 Oct 08, 6:22 AM

    I agree with George, that the discussion should be kept on the board.
    I have a program for the Psion III called Sightmaster 3. I am basically
    want to get all the functionality of this program and a few more things
    programmed into the HP49.
    I am programming with User RPL - should be compatible with HP48. I believe
    it takes up more space than system RPL, but I'm new to "advanced" HP
    programming. My previous HP was a HP38 which was relatively simple to
    program. I started trying to write the software using a line editor on my
    PC but found it was easier to write straight into the HP 49. By the time I
    debugged and got things to load I was loosing a lot of time. (By the way, I
    have an excellent editor called Ultraedit very good for all sorts of
    programming worth downloading to try it www.ultraedit.com)
    At present I am working on getting the engine running and not worrying
    about interfaces.
    I am writing each equation as a separate  routine and then calling these
    from a main program.
    I have successfully programmed in the sun and moon,  the moon computations
    are within .2' of values given in almanacs of various years - randomly
    picked dates. I guess this is sufficiently accurate for our navigational
    purposes. The sun is pretty well spot on.
    I have completed the progamming of the stars to give me the apparent
    position of a  star from the proper motion. However I have not yet added
    the proper motion for all the "navigational" stars.
    Planets are giving me a headache, I have calculated the elements for
    planetary orbits but need to get heliocentric coordinates and then to
    geocentric coordinates; when you start to read Meeus you'll know what I mean.
    At 19:49 06/10/01, you wrote:
    >Hi Aubrey,
    >It sounds like you are going down the same track as me.
    >My copy of Meeus is in the post on the high seas. Meanwhile I intend
    >trying to get some of the almanacs and sight reduction programs on
    >www.hpcalc.org working...but
    >have to build my HP to PC cable first! At first glance, these programs
    >don't seem to have a friendly user interface, and its very difficult
    >working through somebody elses RPL.
    >I would certainly be interested in sharing experiences or collaborating to
    >reduce work. What programming language are you using? I understand User
    >RPL is basically compatible across the 48/49 range, provided care is taken
    >not to use the special instructions peculiar to the later machines...ie
    >User RPL is upwards compatible, but not downwards if the extended
    >instruction set in later machines is used. Does your manual have any
    >comments on compatibility??
    >Perhaps we should take this discussion off List?? Others who may be
    >interested can follow.
    >Lee Martin
    >----- Original Message -----
    >From- Aubrey
    >Sent: Friday, October 05, 2001 11:41 PM
    >Subject: Re: HP 48GX Sight Reduction Programs
    >I recently bought a HP49G and a copy of Meeus Astronomical Algorithms. I
    >have been busy doing some initial programming.
    >I have got almanac sorted out for sun positions and moon positions.
    >I'm finding it quite a good way to learn my way around the HP programming
    >Progress is quite slow as I have too many other things to do, but I'm
    >happy to share my experiences with you.

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