Hello,I tried to figure out how this works.Does Guide use Brad Schaefers
formulae without mathematical modifications?And where can I get the
algorithm? When trying the original program by Schaefer I get different
values.
I used as an example the 10th of September 2004 at 05:15:00 Central
European Time (MEZ) seen from Ratzeburg in northern Germany (53.71n,
10.77e, height 20m). As Temperature I used 18.3 degrees (65F) and 60%
humidity.I was interested in the near conjunction of Mercury and
Regulus. Were Mercury and Regulus visible for the naked eye?
Using Guide the Visual limit is 0.69 (sun -4.7 degrees below horizon,
Mercury 10.7 above) a realistic value that says – Mercury could be
seen but not Regulus.
When using the program given in Sky and Telescope with the same
circumstances I get about -1.53 as a visual limit – the same result
that comes from Astronomical Visual Limits
<http://www.nature1st.net/bogan/astro/optics/vislimit.html>
when using the same parameters. That means none of both objects could
bee seen by naked eye.
When using the algorithm on the websiteVisual Limiting Magnitude
<http://cleardarksky.com/others/BenSugerman/star.htm>
that also should build on the same algorithm from Schaefer the result is
1.76 (experience 6, age 43, snellen-ratio 1.0) – meaning both
objects could be seen in sky.
My experience and observations speak for the result of Guide –
Mercury could be seen in the morning sky but Regulus was to faint for
being seen with the naked eye.
Therefore I am interested how Guide is calculating the value.
Greetings,André



[Non-text portions of this message have been removed]