Illustrating Precession
There was some talk about precession about two years ago namely:
skymode grids (equator, pole point, etc) don't account for precession. Projected grids from the Earth do (although the projected ecliptic doesn't work for that). It'd be great to have fully featured precession demonstration.
It would also be really cool if there was a good way to maybe disable the Earth's annual motion so one could smoothly slide between the multiple thousands of years to see precession?
I really wanted to make sure these things were still in the development path!
Customer support service by UserEcho
Here's a video from other software demoing what I'd like to be able to do: https://www.dropbox.com/s/qt92z7cpxpkcz36/precession.mp4?dl=0
I don't leave the surface, stay locked on 0 RA. In one version I turn of the sun and planets to avoid their distraction and we can see the constellations roll around 0RA. In the other I turned it back on and we see the sun go around. Since in UV even with daily motion off (aka annual motion on) we still have the Earth's annual motion around the sun there's no getting around the constantly whipping around effect.
Forwarding on to devs, thanks Dan!
Hi Dan,
I tried few different ways. Here's what I think worked for the projected markers on Earth.
1) Add "Precession Circle" Marker on Earth.
2) Add "Poles" Marker on Earth and have it as Projected.
3) Go to sky mode.
4) Enter the command: Earth.planetfx. This to remove the atmosphere. Make sure that you can see the precession
circle.
5) Ctrl+Left click the "Orbit" mode button in "Navigation" dialog box. This will shift the camera to orbit mode
immediately.
6) Now by increasing the time by say 99 years/second, you should have see a similar effect as that in the clip you showed.
Note that using a projected "Ecliptic" marker won't behave in BC dates. Also for dates roughly outside -6000 < d < 6000, the pole point veers off the precession circle. But that is still a big arc to cover and I think it's good enough for a demonstration.
Also you can increase the label size of the "Precession Circle" Marker.
Let us know if that helps.
This still isn't really satisfactory since we do want to demo it from sky mode and also want to automate a lot of it through scripting (so not having to manually ctrl+click the navigation button).
In general it'd also be really great to improve Uniview's reliability beyond 1600-2200ish and/or clarify Gergorian/Julian conversion. For example, we are preparing a show on eclipses and had to do some fakery to get Columbus' Feb 29 1504 lunar eclipse to work. We have been totally unable to do the -584 Eclipse of Thales (the moon seems to be every slightly off)