HP67/97 Navigation Pac I Update

[MikeO]

For those interested in HP67/97 Nav Pack I:

A friend of mine, who's using my HP97 emulator, asked me if I could look at the Navpac Star Sight Planner program (NAV-05A1), and figure out how to update the star data on the data card (NAV-05A2). Using the emulator, I reverse engineered the data extraction formulas used by the program, and used them to figure out what was wrong with the compression formula given in the manual.

Using current nautical almanac data, I was then able to produce a new version of the NAV-05A2 data card that results in about a 22% improvement in accuracy. The data card contents are listed below:

Encoded Star Data

 As of 8/8/2008

 Replaces NAV-05A2 Data Card

   0.0000000  0 -

   0.3393721  1  |

 18386.60088  2  |

 81716.37301  3  |

 72263.47855  4  |

 22270.40621  5  - Primary Registers

 54475.24512  6  |

 46255.79618  7  |

 59588.47426  8  |

 34622.74119  9 -

 89094.55238  0 -

 43536.15781  1  |

 41856.60219  2  |

 85191.19147  3  |

 56337.23035  4  |

 39743.84219  5  - Secondary Registers

 9228.353652  6  |

 64772.70976  7  |

 43174.28825  8  |

 64906.45485  9 -

 82117.25485  A

 44888.67165  B

   0.0000000  C

   0.0000000  D

   0.0000000  E

Data Reference:

http://www.tecepe.com.br/scripts/AlmanacPagesISAPI.isa/pages?date=08%2F08%2F2008

I hope this comes in handy!

-Mike

Edited: 8 Aug 2008, 10:27 p.m.