Revising default list of comets

[alex-w]

Description

The default list of comets contains now a few very bright comets - at least visual magnitude 0 - so, this is good naked eye observed comets.

Fixes #3261
Fixes #1241
Fixes #561

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• This change requires a documentation update

Checklist:

• My code follows the code style of this project.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (header file)
• I have updated the respective chapter in the Stellarium User Guide
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[alex-w]

OK, the PR is ready to review & merge

[gzotti]

Other than that, the list should be good for now (23.2). We could think about packing only 2020 and later in the default distribution, and add extra files to load for e.g. showpieces 1950-2020, all comets 1950-2020, and then shorten the 1000comet list to end in 1950 (to avoid overlap). But it's just tedious reformatting. If there is a better list to replace the 1000comets, fine for me. But for some of the historical comets I tried to match the tail parameters to photos or old prints, so these data should not get lost.

[alex-w]

Other than that, the list should be good for now (23.2). We could think about packing only 2020 and later in the default distribution, and add extra files to load for e.g. showpieces 1950-2020, all comets 1950-2020, and then shorten the 1000comet list to end in 1950 (to avoid overlap). But it's just tedious reformatting. If there is a better list to replace the 1000comets, fine for me. But for some of the historical comets I tried to match the tail parameters to photos or old prints, so these data should not get lost.

Probably it will be few loadable lists for old comets (ancient, renaissance, middle age or something other base for sorting the data), but I fear we should add some GUI elements in Solar System Editor plugin to manage the lists. And what about non-cometary data in ssystem_minor.ini file? We need to split the data onto few files/lists or add something to correct manage whole SSO.

The packing only 2020 and later in the default distribution may be acceptable, but what about periodical comets?

In any way, proposed task touches issue #3240, and it should be solving in separate PR, because it related to changing the architectures of SolarSystem class and SSE plugin.

[gzotti]

You can of course add some Epoch/Perihel date filtering to the "load data from file", but it's not topic of this PR and probably something for 23.3 or later. If such a filter becomes reality, there is no need to split data files per antiquity/medieval/renaissance/.... The data files can be named by their original sources, the filtering will select what user wants. I assume this is a very small, specialized user group here. If there is a list "best comets since 1935", this should make even our oldest observer/users happy who may want to recreate their earliest observations from the 1950s.

Periodical comets still need at least one entry per apparition, so it's no difference. (You cannot use data from some 2018 apparition to compute the 2024 or 2035 orbit.)

Non-comet minor objects: Not sure what "typical" users want. A few asteroids (1-20?), the dwarf planets, some KBOs should be there permanently, with updated elements per release. Smaller ones if they are something worth demonstrating. (Spacecraft visits/impacts, ...) There was one memorable event at the evening of the Chelyabinsk meteor fall, when a small object passed Earth. However, in these hours, its orbit was changed by Earth's gravity, so this cannot even be properly demonstrated with one element set (I had used elements from JPL/Horizon to create a chain of objects with elements 1 hour apart, but average users would be confused.). Experienced observers will create their own set.
I would like to see the asteroid belt symbolized by a particle system driven by real elements for 5.000~250.000 asteroids computed on the GPU (Kepler elements, fixed 5 iterations). Identification of single dots will not be possible. This has been a wishlist topic for a plugin since Launchpad times.

[alex-w]

So, is the current list (for v23.2) good for you?

[gzotti]

Yes, should do for 23.2.

[alex-w]

Oops... I found issue in the filters for comets/asteroids in the plugin and it fixed now. Plus I've added all comets, where discovered/recovered in years 2022-2023.

[github-actions]

Hello @alex-w!

Please check the fresh version (development snapshot) of Stellarium:
https://github.com/Stellarium/stellarium-data/releases/tag/weekly-snapshot

[github-actions]

Hello @alex-w!

Please check the latest stable version of Stellarium:
https://github.com/Stellarium/stellarium/releases/latest