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HM Nautical Almanac Office: NavPac 3

Status of NavPac 3 Software

The release dates of the NavPac version 3 software are given below.


Please Note: No attempt has been made to internationalize the NavPac software to deal with other languages, nomenclature and date formats. It should be noted that decimal points are input and indicated by using the period (.) or full stop and that dates (year, month and day) and angles (degrees and minutes) are best separated by a space.

Log of Changes / Bug Fixes

Version 3.1.8

This release corrects the following issues found in version 3.1.6.

  1. Some users, e.g. those from Finland and Austria, whose Windows settings for date formats are not those expected by the software may find that NavPac crashes with an error "Run-time error 13: Type mismatch" before the splash screen appears. This error occurs while the program obtains the current date from the operating system.
  2. Other non-UK users whose Windows settings for dates are incompatible with NavPac may experience some problems when inputting dates and displaying dates. Similar error messages to Item 1 may be seen.
  3. If your system is not connected to the internet and you try to access the NavPac website from the main menu then the program may crash.
  4. When a user clicks on the print button to print the Log from Sights then the program will crash with an error "Run-time error 9: Subscript out of range" if any of the following are not the default values, namely, the height of eye, index correction, temperate or pressure.
  5. In Finder, inconsistencies in displaying the selected way point near the end of the route report and the use of the keyboard to move up and down the list of way points have been corrected.

Version 3.1.9

This release addresses and corrects the following issues found in version 3.1.8.

  1. In Sights – Astronomical Observations, a fatal error occurred if the New Observations button was selected and the previous observation had not been selected for use, i.e. the tick box (Use/Ignore Sight) to the right of the Enter button had not been selected so that the information produced by NavPac, in the right box, was still printed in red.
  2. In Sights – Astronomical Observations, a fatal error occurred if users happened to select an object by clicking on its symbol in the Sights – Astro – FindIt, altitude/azimuth diagram.
  3. An error has been detected in the magnitudes of five stars used by NavPac. The magnitude discrepancies are given below.
    Al Na'ir+1.9+1.7
    Rigel Kentaurus0.0−0.3

    The following procedure has been approved for correcting this issue:

    • Ensure NavPac is not currently running on your computer.
    • In the "cdata" directory of the NavPac installation (by default: C:\Program Files\HMNAO\Navpac 3\cdata), create a new folder entitled "old".
    • Move the ASCII "STARS3.dat" file found in the "cdata" directory into this folder.
    • Download its replacement.
    • Once the download has completed, copy this downloaded file (STARS3.dat) and paste it into the "cdata" installation directory (by default: C:\Program Files\HMNAO\Navpac 3\cdata).

    This will enable NavPac to use the corrected magnitudes.

Version 3.1.10

This release addresses and corrects the following issues found in version 3.1.9, in particular in option Finder - Rhumb Line/Great Circle Routes.

  1. The time at the rhumb line way points in the route report are incorrect as it has been given to the nearest hour, with zero minutes and seconds. However, the total time displayed in the "Destination" block is correct.
  2. When there are no way points on the rhumb line between the start and destination, then the rhumb line distance and course were not calculated and the great circle distance and course were displayed instead.
  3. When courses were due east (90 degrees) or due west (270 degrees), then the values used were in the wrong units and thus all further way points were incorrect.
  4. It is highlighted that the rhumb line formulae used in NavPac fail at the north and south poles. In the cases where these points may be generated, then the program sets the resulting latitude to be +/-89.999999999 degrees (i.e. just not 90 degrees to the precision of the computer).

This new release is available on CD in NavPac and Compact Data 2016-2020 and provides additional data covering the period 1986 to 2020. The maximum number of coefficients allowed for the Chebyshev coefficients for the longitude and latitude of the Moon has been increased to 16. This change was required to maintain the precision of the position of the Moon at 0.2 minutes in the period 2016-2020.

  1. The word "mercator" has been removed from the position plot.
  2. The version number has been inserted on all screens to make version idenitification easier.
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Last modified: Tuesday, 10 January 2017 at 10:30:29 GMT