Lunars: apparent coding error in moon/sun LD limbs

[artjohnston]

I did a sun lunar and there appears to be an error in the coding. When I change the Limb input box from Near to Far, there is no change in the results.

Sun lunar.pdf

[rbossert149419]

Lunars for Sun-moon sights. The first case is supported by Lunars. you can do Near Edge of the moon touching the Sun. And by definition, that would be the nearest edge of the Sun. But, there might be a secondary problem with your first case. For the altitude sight, did you really intend to select Center as the Limb for the Moon and center of the Sun? The vast majority of Mariners would shoot either the upper or lower limb of either bodies depending on what they can clearly see touch the horizon when taking the sight. Cel Nav does a good job at Limb Correction. Center has always been a Cel Nav option, presumably for those who have bubble sextants.

For your second case, Lunars doesn't support Far edge of the Moon touching the Sun. The reason why Far is not supported is because the Far Edge is shaded by the bright Sun when the illumination is less than 100%. On Jan 12th, the Moon's illumination was 32%. The 2nd reason why Far is not supported for the moon... When the Moon's illumination is 100%, Lunar Distance would be approximately 180 degrees, clearly outside the measurement range of a Maritime Sextant.

Near is the only Sun-Moon Lunar case supported. The training guide illustration on page 9 shows the cases supported and the cases not supported. Reasons for the "un support" cases are identified.

[artjohnston]

I'm talking about the near and far edges of the sun, not the moon. Either the near of the far edge of the sun are possible sights and either option should be in there.

[rbossert149419]

You opened issue #236 a while ago on this very topic and after we discussed it, you were ok with as we designed it and then you closed the issue (found under closed issues. It is probably worthwhile to take a look at it again.

In Lunars, Near and Far has to do with the Moon only. There is no Near/Far setting for the paired celestial body like the Sun.

It would be difficult to measure the Sun's Far Edge and the Moon's Near Edge where they just touch at the tangent. They'd be on top of each other. And with the brightness of the Sun and the relative dimness of the Moon, it is not likely you'll find the exact moment they just touch exactly at the tangent point. One would overshoot the other. You mentioned back in #236, "eclipse" each other. Your description was apt.

In the age of Lunars, navigators knew this inherent problem and brought the Sun and Moon together where the Near Edge of the Sun met the Near Edge of the Moon. They knew that was the best sight to take. If the moon was brought to the other far edge of the Sun, they knew they would have a much larger error in measurement. And that wouldn't work out for them. Thus they didn't do it. They selected the best sight they could do.

This is an illustration of what's not supported.

And this illustration is what is supported.

[artjohnston]

You are wrong. Yes, there is a near and far for the sun when you are doing lunar. You are correct that in #236 I incorrectly thought there was also a near and far for the moon when doing the sun.

What I remember agreeing to is that on lunars with stars, the moon sight has a near and far. And what we agreed to is that on lunars with sun, there is still a near and far and that would then apply to the side of the sun you are sighting to.

It is very easy to sight on either side of the sun. I am bringing this up because it is not currently support, and that should be changed. Doing lunars on either side of the sun is easy, and certainly would take little code changes to fix that bug.

[rgleason]

Let's be nice to each other here. We are on vacation from this project for awhile, but it is good to think about it and work with it to understand where it can improve, but let's be tactful and nice and not get emotional about it. Its just a program and its far more important that we be friends and comrades that work together. We will accomplish much more that way. Be gentle, listen, discuss, think about it, listen. People generally want to do the right thing.

[artjohnston]

Near and far on sun lunars are easy to do--I did it prior to making this new issue when I noticed that that that CelNav capability was disabled. I see no reason that it should be disabled, and it should be re-enabled.

An overview: I have make comments on how to improve CelNav, and some of them have been wrong and I've admitted that and moved on.

But I have also sent other comments, which I put a lot of work in and think would be ways to improvement CelNav, but it appears that all my comments are dead-on-arrival and ignored--unless rbossert149419 gives them his blessing.

The few comments that I do get back from rbossert149419 are arrogant and belligerent. This is not collaboration and not how this should be working.

[rgleason]

Happy New Year!

Art. consider the discussion about how to find good lunar bodies, you initiated that discussion and between the two of you figured out some pretty nice ways of providing that information. You have had an impact on this project. Things don't move as fast as you expect them too, others are on a "vacation" and its worthwhile using the software and thinking about it. We need to work as a team here, you, Bob, Stalien and me, in an cooperative environment or I am pretty certain this project will just flop/stop.

Right now I have my full attention on another project. Sorry.
rgleason