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Hello!

I regulary use P. Hirose’s programm Lunar4.4 to find topocentric star/star angular distances. But for fast clearing lunars (or fast finding apparent lunar distance from known place) usually I use Frank’s online calculator.

At the begining of  April I took some sets of lunar distances but was not able to check them by Frank’s calculator, becauce it did not work that day. I did the calculations using Lunar4.4 program. The next day I repeated the calculations by Frank’s calculator and was surprised: Lunar4.4 program produced results that differed almost 0,3’. It is a considerable difference, I think.

I added Venus lunar input printscreens in the attached pdf file from both calculators. (The latitude, longitude, time values are rounded.) As you can see, the geocentric lunar distances the both calculators generates identical. But apparent distances are different. I could not find the reason of this difference. The difference in results was not only in this particular Venus lunar. It was present also in Procyon and Betelguese lunar sights (about 0,2').

Any comments from Paul or other members will be highly appreciated.

Modris Fersters