Version 10.0.2

This update 10.0.2 removes the necessity to enter negative values for South latitudes and declinations, East longitudes, watch error and zone description. All you have to do now is to enter the letter identifying direction (N, S, E, W) for coordinates, or (f, s) for a fast or slow watch. The software will take care of the sign. This way of entering data is more compatible with known sight reduction forms and avoids the common mistake of forgetting to apply the negative sign to the minute values as well as to the degrees.
Paul

Version 10.0.1

A small correction to version 10.0 (already!). You might have noticed that on the Observer's Meridian Plane projection, the LHA meridian appears dashed when in the "hidden" portion of the earth (or the far away part of the celestial sphere). I had forgotten to apply the same logic to the azimuth great-circle from the observer's position. Also, I added the arc minutes-seconds increment to the GHA corresponding to the UT minutes-seconds of the observation, for those who would like to compare results with the numbers obtained from the tables and the CPS-ECP forms. The only decimal-degree value was visible.
Paul

Version 10.0

In this version 10.0, the North Pole View graph has been replaced by a time diagram, illustrating the observer's meridian at the top, and the relative hour angles of the Greenwich meridian (upper and lower branches), the GHA of Aries, the LHA of the observed celestial body and the sun meridian. The graph can also be interpreted as a view of all those meridians as seen from a position over the South pole. The declination circle is also shown. The drawing of the time diagram is part of the Canadian Power Squadron method of reducing a sextant sight, to help visualizing the various parameters.
A few minor bugs have been corrected. Your comments are welcome.
Paul

Version 9.4.4

A few bugs were found in the plotting of the circles of position, when they cross the 0° or the 180° meridians. They have been corrected in this version 9.4.4, together with some other minor errors. The spreadsheet for the calculation of great circles has also been corrected accordingly (GCirclenav_ver_2.2.xlsx). Please, keep me informed if you find any other problem. Thanks.
Paul

Version 9.4.3

This last upgrade improves the data input blocks to facilitate the solution of midday or meridian passage sights. In such a case, the GHA at meridian passage should be converted to equivalent East or West longitude and replace the AP (DR) longitude in order to make sure the azimuth line coincides with the meridian. Then, the reading of the "Position of LOP" on the "LOP plot" sheet is the observer's position at meridian passage. Some minor bugs have been corrected and the possibility to select which sight will be used to center the graph was added (useful for the plotting of running sights).
Paul

Version 9.4

The new AstronavXls version 9.4 is now available.
This new version essentially includes two additions:
1- A data input block for the local watch time of the sextant sight, including watch error correction, calculation of the local Zone Time, input of the Zone Description and calculation of the universal time (UT) and corresponding date. In the previous version, the sight UT was entered directly and calculations from the watch time had to be done outside the worksheet. This is to make the entries more compatible with the CPS (Canadian Power Squadron) calculation sheet.
2- Spin buttons (up, down, left, right) now allow to move the center of the map displaying the circles of position in order to re-center the intersections.
The User Manual was also updated.
Paul

Version 9.3

This new version 9.3 includes the corrections of several bugs found in version 9.2, particularly for the plotting of the circles of position in the vicinity of the date line (±180°). It also corrects problems with the "running LOP" function, taking into account the displacement since the last celestial sight.
The great circle software (GCirclenav) has also been adjusted for the crossing of the ±180° meridian.
Paul

Version 9.2

AstronavXls version 9.2 is available for downloading.
Several changes were made for the user-friendliness of the data input sections and to make them more compatible with the forms used by the CPS. The orientation of the "Zenith View" and the "Pole View" graphes was also changed for ease of interpretation. Several minor "anomalies" have been corrected in the process.
The big improvement of the version 9.x series over version 8.0 is the plotting of true circles of position (LOP) as opposed to approximated circles in the previous version. The plotting is accomplished by rotating a great-circle arc around the position of the celestial body, of length equal to the distance from the body to the observer (sextant observed co_altitude), using great-circle equations, and finding the end coordinates. Of course, because of the complex trigonometric functions involved, several ambiguities arise, most of which I think I have solved. There may be a few remaining, please if you find any, let me know.
I also added another Excel sheet software (GCirclenav_ver_2) for the calculation of great-circles of navigation.
Your comments are welcome.
Paul

Invitation

Your comments are welcome.
PC