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Old 17-07-2018, 10:12 AM
gregbradley's Avatar
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gregbradley is offline
Join Date: Feb 2006
Location: Sydney
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Originally Posted by rally View Post

Tpoint and the Paramount handle meridian flips really well
No need for fudging it !

You would do your normal Tpoint mapping for Polar Alignemt reporting using 6 plus stars within a few degrees of each other on the same side of meridian.
Then once you have used the Polar alignment report to adjust for a good Polar Alignment (you might do 2 quick iterations to get it down into the +/- 10 arc second range for both axiis)
Once you have a good PA on one side of Meridian, then generate a new calibration run which has about 40 mapped points on both sides of meridian and have them +80 and -80 degrees declination and some around the celestial equator.

This will produce a Tpoint model that should have you within about a stars diameter anywhere in the sky.

You need to do that as the manual states to differentiate between the different term errors that can be caused by different things - "This is so that TPoint can distinguish between the HA sync error, IH, and the OTA/declination non-perpendicularity, CH."
Doing the mapping on both sides of meridian ensure that Tpoint can correctly identify the sources of those errors and correct them.

I assume you are using TheSkyX and can so a Super Model and you are doing your Tpoint mapping using the camera rather than swapping between visual and camera

There is a good discussion of this in the Tpoint Add On manual available online.

Thanks for the reply Rally. Its not what I was asking though. I do use TPoint and supermodels and polar alignment and yes it does a fantastic job.

But here is an example of what I mean. I am imaging NGC6188 so I do closed loop slew to NGC6188 that puts it exactly in the centre of the image.
I don't want that as its not framed nicely so I move it until I like the framing. Now later I need to do a merdian flip. If I do closed loop slew I am back to NGC6188 being in the middle of the image again and I have to remove it to frame it the same as I was just imaging on the other side of the meridian.

I was wanting to know if there is a way to plate solve the framing so when you flip it goes to that exact framing not just putting the object in the middle of the image requiring moving it again to frame it the same.

I have noticed if you add a point after a plate solve it can be displayed on the map. Then closed loop slewing may go to that point rather than the middle of the object? Not sure. The flip mount tool in Sky X does not put the object in the same position of the image. That's the problem.

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