Meridian Flip

[James Chase]

For those of you using an equatorial telescope mount...  What special considerations do you use (in Stellarium) when a meridian flip is required?  It appears when the equatorial mount switch is turned on, Stellarium only has one way  of looking at the sky - with the RA axis oriented only to the West side of the mount (with DEC looking East).  Is there a way to get Stellaium to "flip" so the apparent RA position is on the East side (with DEC looking West)?

[Hans]

Hi James,

Stellarium does not even know whether your mount is alt-az or equatorial, as such it does also not have meridian flip knowledge.

Triggering a meridian flip 'for most mounts' involves a simple goto command, 'most' mounts then decide themselves whether to perform a flip or not.

This can be a goto command to the same position the mount is pointing at now.

-- Hans

[JAY RESPLER]

Hi.

Not sure exactly what you need, but do you know that you can flip the screen left to right and up/down?

Jay

[Alexander Wolf]

Hi James and Hans!

Ср, 22 дек. 2021 г. в 02:13, Hans <ha...@lambermont.dyndns.org>:

Hi James,

Stellarium does not even know whether your mount is alt-az or equatorial, as such it does also not have meridian flip knowledge.

Triggering a meridian flip 'for most mounts' involves a simple goto command, 'most' mounts then decide themselves whether to perform a flip or not.

This can be a goto command to the same position the mount is pointing at now.

Probably James say about Oculars plugin.

--

With best regards, Alexander Wolf.

[Alex D.]

This could be an interesting option for the Oculars plugin or the Telescope plugin: an automatic flip whenever approaching and/or crossing the meridian; and optionally, a simulation of the telescope moving across the sky when flipping, including a simulation of the path and the rotation of the camera. But that could be quite hairy to implement...

Maybe in planning a session, the meridian line should be set (standard shortcut ';') so that one sees when the flip will happen.

The Archaeolines plugin can also be used to define a "zone" around the meridian where flipping will occur (eg 180 +-5 degrees).

-alex-

On Tuesday, December 21, 2021 at 6:21:00 PM UTC+1 James Chase wrote:

[JAY RESPLER]

Be aware that using Oculars turns off Scaling and Mag limit.

Jay

[Alex D.]

Mag limit is a setting of the Ocular plugin.

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[JAY RESPLER]

The only setting that I see in the plugin is 'Auto limit stellar mag'.

I'm referring to the 'Sky and View options window, F4'.

In SKY tab there is LIMIT MAG. In SSO tab there is SCALE MOON.

Those, and maybe others, get unchecked and turned off when Ocular is turned on.

Jay

[Georg Zotti]

This question is about the mechanical performance of a meridian flip in a real physical German Equatorial telescope mount. Hans has explained it. It has nothing to do with the Oculars plugin or screen flipping.

[Alex D.]

Try this: enable the "auto limit stellar magnitude" setting in the Ocular plugin and compare the magnitude limit value in the F4 screen before and after enabling Ocular view.

[Alex D.]

First of all, the question is NOT about "... mechanical performance of a meridian flip in a real physical GEM ..." but "What special considerations do you use (in Stellarium) when a meridian flip is required?".

Secondly, Hans is correct, Stellarium does not know about flipping.

Thirdly, MY follow up is a tangential. off-topic idea ("This could be an interesting option for the Oculars plugin or the Telescope plugin...") that expresses a suggestion, a possible improvement of Stellarium to better deal with this highly interesting phenomenon (which,. if not correctly understood/mastered, can damage equipment...). A suggestion that is rooted in this discussion, showing that there could be a use case to implement such behaviour in Stellarium.

After all, there is already a primitive Telescope simulation possible (the Telescope plugin), so one day the question will come up - what happens in Ocular view when a telescope performs a meridian flip? Answer: the Ocular image ends up flipped. Therefore, in this use case, the Ocular plugin could also be an actor in this use case. An extension of the use case is to simulate the trajectory of the telescope, and how that looks like in Ocular view. Too far-fetched? Yes. Interesting? Yes. Feasible? Probably. Desired? I don't think so.

It is this kind of "off-topic" behaviour that spins interesting new ideas; rather than be negative, one should accept this kind of discussion with open arms. This is a human behaviour that has spun many new ideas that lead to new discoveries etc.

And this is how software engineering works, how software evolves.

rgds,

-alex-