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    Astron Version 2.2
    From: Bill Ritchie
    Date: 2019 Nov 11, 00:09 -0800

    Astron Version 2.2.

    I announce this release which has become necessary as Astron’s Google Map free allowance has started being reached. The Google Map version of the sight plotter now blanks whenever any data is changed and needs a button click to redraw. Previously it automatically redrew with every change, which the Astron chart continues to do.

    Posts on NavList have inspired additions that may be of interest. “Correcting an out of date Nautical Almanac” has led to adding a page to show almanac data and apparent position for all 65 bodies. Frank’s posts on “Lunar Lines of Position” have resulted in the ability to show these on the sight plotter and to be advanced, retired and freely mixed with traditional LoPs.  The plotter can also show the lunar distance at valid locations as the cursor is moved around the chart. Posts on using a sextant at inland locations have resulted in allowing the observer’s altitude to be entered (with either ambient T&P or estimated MSL T&P) and refraction reduced accordingly. In response to posts on “Dip Short”, Astron now calculates the dip for a known distance off and, indirectly, can show the unknown distance of another vessel from its waterline depression. Other minor additions, changes and bug fixes are listed in the User Notes Appendix 4.

    Version 2.2 completes my intended features, plus a few others that have materialised along the way. (“You never know what you want until you have seen what you thought you wanted!”). I will continue to give Astron full support and consider requests for relevant improvements or additions.

    Astron has been updated to use features of JavaScript ECMA 2015 that enforce more rigorous coding practices. Microsoft state that Internet Explorer does not, and will not, support ECMA 2015, so Astron will no longer run under that browser. A difficult decision, but IE now has a reduced user base and I like to use stricter code and to move with the times. Does anyone else remember those “Bdos Err on A:” messages?

     Astron V2.2 can be run (and saved for offline use) from   https://friendsofthevigilance.org.uk/Astron/Astron.html (updated)

    The User Notes and a brief PowerPoint presentation of Astron can be downloaded from the same folder. I always welcome feedback from NavList contributors to my email given in the User Notes.

    Bill Ritchie.

    Home 50N 003W, presently 12S 050E.

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