More features for Observability Analysis

[alex-w]

Original report by Keatah: https://bugs.launchpad.net/stellarium/+bug/1045297

Observability Analysis plugin (ideas for more features)

Things to add to the plugin:

• Distance from Sun for Solar System objects
• Heliocentric x,y,z distances
• More info for phases of the moon - Age, Angular Size.
• Some sort of graphical popup moon calendar
• Degree of subtention
• Some sort of general astronomy calculator (this could be another plug-in or a totally different application entirely)

[gzotti]

Some of the numbers should be given only when accuracy issues have been solved. Else people would start using Stellarium as reference solution...

[axd1967]

Maybe overkill, but a dialog could be shown that warns the user about the accuracy of the graphs, or some other way to indicate that accuracy is not good for reference use?
Just freewheeling: how about making the lines thicker, as fine lines imply high accuracy?

[gzotti]

@axd1967 Do you want to confirm a dialog for every numerical result that is technically wrong in the last displayed decimal figure? You will hurt your index finger from clicking.

Appendix F in the Stellarium User Guide is where you find accuracy estimates. As long as the version number is 0.*, you should not use Stellarium as reference source for numerical ephemerides.

[axd1967]

No... I was thinking about a one-time dialog with a checkbox that allows the user to hide it "forever" (or until reset by some other means). The dialog could contain one or more hyperlinks to one of these:

• https://github.com/Stellarium/stellarium/blob/master/guide/app_accuracy.tex,

• stellarium/guide/app_accuracy.tex

  Lines 10 to 30 in 1dbadae

  	\chapter{Accuracy}
  	\label{ch:Accuracy}
  	Stellarium originally was developed to present a beautiful simulation
  	of the night sky, mostly to understand what is visible in the sky when
  	you leave your house, i.e., for present times. To save computation
  	time, some concessions were made in astronomical accuracy by using
  	simplified models which seemed acceptable at that time. However, many
  	users started to overstress Stellarium's capabilities to simulate the
  	historical sky of many centuries in the past, and found --- or even worse:
  	did not find, but simply published --- the resulting inconsistencies and errors.
  	Unfortunately, celestial motions are indeed more
  	complicated than a simple clockwork, and the process of retrofitting
  	detailed and accurate models which started around v0.11.0 is not
  	completed yet. Therefore, when using Stellarium for scientific work
  	like eclipse simulation to illustrate records found in Cuneiform
  	tablets, always also use some other reference to compare, and of
  	course specify the program version you used for your work. (The next version
  	may be more accurate or at least provide different results!) You can of
  	course contact us if you are willing and able to help improving
  	Stellarium's accuracy!

• https://github.com/Stellarium/stellarium/releases/download/v0.19.2/stellarium_user_guide-0.19.2-1.pdf.

[gzotti]

I made such a one-time warning for users with too old computers that they should expect graphic problems. Those still reported about graphics problems. "Ah yes, there was some warning, but I clicked continue". Do you think anybody cares for what they confirmed when accepting some popup dialog that you see once just after installation or at first run?

[alex-w]

Couple features are implemented in main code already:

• Distance from Sun for Solar System objects
• More info for phases of the moon - Age, Angular Size.

Plus one feature is implemented in debug mode:

• Heliocentric x,y,z distances

Probably we may add it in the release mode too, but... how it really necessary?

[alex-w]

What is "Degree of subtention" in astronomical application?

[alex-w]

I mark last item as solved due AstroCalc tool