Camera rotator question


#1

I recently picked up a Pyxis camera rotator but I have not started using it yet as I am waiting for some adapters.

I have read the SGP manual pages related to rotators, but I had a question about meridian flips.

In general I think there are two possible behaviors for meridian flips:

  1. Use the rotator for initial target centering and framing, but leave the rotator alone after the meridian flip. I can always rotate the subs during processing as I did without the rotator.
  2. Command the rotator to rotate 180 degrees after the flip. This would have the benefit of allowing PHD2 to select the same guide star after the meridian flip. (OAG)

I assume SGP works as #1, right?

Would it be possible to do #2 somehow? My motivation for using the rotator is less for framing, but more for guide star selection.

Andy


#2

For step #2, I suggest to take flats before rotating the camera. Might be difficult unsupervised even with SGP unless you are using Alnitak Flip-Flat light box.

Peter


#3

Yes. SGP does #1 at the moment to avoid taking multiple sets of flats like Peter mentioned. I’ll add something to our backlog to allow the camera angle to remain the same between flips.

Thanks,
Jared


#4

Thanks, Peter. I will be using a wall-mounted flat panel.
Andy


#5

Thanks, Jared. That will be a useful feature for automated setups. In the meantime, even a meridian flip scripting hook would serve my purpose, is there one at present?
Andy


#6

There is not. Although I’m not entirely sure how that would be helpful either. Is the thought that you would have the script rotate the camera back to where it was? This would likely not work as SGP has to store the actual angle internally as rotators do not support sync.

Thanks,
Jared


#7

Hi-

I have a pyxis and intend to use it with meridian flips according to method 2, where the oag is rotated 180 degrees on flip. In my case, all I need is for SGP to rotate the pyxis 180 degrees from the original angle on meridian flip. SGP is in control of the pyxis - so sgp would need to be the one to rotate the pyxis - and to recognize the meridian has flipped.

With MetaGuide I am implementing this so SGP doesn’t need to know anything about guiding. MG will notice meridian flips on its own - and the user will tell MG if it is a guidescope or oag that flips. But sgp would need to do the pyxis rotation on flip.

So if an object is specified to start imaging in the east, the oag angle for the east view would be entered - and later when the meridian flipped sgp would know to add 180 to the angle.

Right now this can all be done - I think - just by breaking the sequence into two parts - and specifying two different rotation angles for the pyxis - and forcing the meridian flip between the two sequences. Then sgp doesn’t do anything special on flip.

The hard part will be making sure the target is well centered so the guidestar does reappear on the oag. If it doesn’t and a search is required - that would be a pain.

Frank


www.mainsequencesoftware.com