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TPoint Paramount vs. AP

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#51 555aaa

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Posted 23 April 2019 - 11:02 PM

FWIW, TPoint corrects for atmospheric refraction at various target Altitudes.

I agree that when you are using Tpoint you are typically also using refraction correction, and I find it frankly confusing to know which software is doing what. None of the Tpoint model terms are for refraction. In TheSkyX, there is a refraction tab on the imaging system setup window, it's not part of Tpoint and TheSkyX can do refraction corrections without Tpoint. TheSkyX, AFAIK, manages the change to the current epoch (precession and nutation), time, and may or may not do refraction, depending on the mount (it always does refraction when calculating elevation). Tpoint manages all the mechanical pointing errors and the spatial orientation of the mount. In ASCOM and in TheSkyX's X2 interface, there's a parameter for each mount type called "NeedsRefraction," and if that is true, it means that the mount is just returning a mechanical position with no refraction correction, but when false it means that the mount has internal refraction correction active. Paramounts return this as true so that TheSkyX will "own" the refraction correction function, some Meade mounts return this as false because they do the refraction correction internally.

 

When you are in the 'Polar Alignment' Tab in Tpoint, there is a checkbox labeled "show alternative polar alignments." That then tells you how you can change ME (the polar alignment error term) to be the true pole, the refracted pole, or some variant between the two. At 45 degrees latitude, there's about an arc minute between the refracted and true pole. The recommendation in the report tells you which elevation setting will minimize which error and it also mentions that there are different optimal elevation settings to minimize wide angle field rotation depending on declination of your target.


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#52 Gene3

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Posted 24 April 2019 - 10:18 PM

You'll then use the utility, called "Telescope Control System" (TCS), to store that limit in the mount's firmware.

 
 
Regarding TCS I have found that the settings are only temporary. Perhaps I am doing something wrong
Bisque TCS, then Utilities, then Mount Slew Limits
I enter the value for east then click Set etc. Then I repeat for West.
SkyX will use those slew limits as long as I do not shut it down. When I restart, say for the following night I have to re-enter the Mount Slew Limits.
If they were actually stored in the firmware  then should they remain even after shut down and restart? My settings do not. 
Am I doing something wrong?



#53 Ralph Paonessa

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Posted 25 April 2019 - 01:36 PM

You'll then use the utility, called "Telescope Control System" (TCS), to store that limit in the mount's firmware.

 

Regarding TCS I have found that the settings are only temporary. Perhaps I am doing something wrong

Bisque TCS, then Utilities, then Mount Slew Limits

I enter the value for east then click Set etc. Then I repeat for West.

SkyX will use those slew limits as long as I do not shut it down. When I restart, say for the following night I have to re-enter the Mount Slew Limits.

If they were actually stored in the firmware  then should they remain even after shut down and restart? My settings do not. 

Am I doing something wrong?

You can save TCS parameters to the mount firmware from the commands at the bottom of the Parameters tab. (I didn't think you had to do this for mount slew limits?)

 

Annotation 2019-04-25 113142.png

 

 


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#54 Ken Sturrock

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Posted 25 April 2019 - 06:52 PM

Strange. I'm away from my gear right now, but recall doing what Ralph says, I set and save the parameters and they're still there forever after in the mount regardless of the computer that I plug into it. The screen shot actually shows what was in the mount when I started it. I took the screen shot before I took the image of the mount.



#55 rgsalinger

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Posted 25 April 2019 - 10:20 PM

My TCS settings remain constant across different computers IF I save them back to the mount. If you keep your computer and mount on without ever saving the parameter back to the mount you will be running with what's on the computer. I am not certain about the use case where you power cycle the mount but I'm pretty sure that the override will remain until you save back to the firmware. If that's the case then changing computers will bring back a different set of parameters.

 

Note that you can save TCS settings to a file and then retrieve them from that file. So you can have multiple settings. This must mean that the mount uses the ones in the computer and not in the firmware if there is a set available. I figure that when you start the SKYX it loads from the firmware every time and then you use the saved settings to override what's in the firmware.

 

TPoint corrects for atmospheric refraction not only in terms of altitude but also use barometric pressure as a proxy for your terrestial altitude which also factors into the equation. If you think about it, as you increase your altitude then there is less atmosphere to refract and so the amount of the refraction goes down. This is only going to be relevant if you are trying to get Protrack to work, I would think. Whether TPoint takes into consideration the other refraction parameters I don't know but I'm certain that it uses pressure as well as altitude.

 

 

Rgrds-Ross


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#56 Gene3

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Posted 26 April 2019 - 03:51 PM

You can save TCS parameters to the mount firmware from the commands at the bottom of the Parameters tab. (I didn't think you had to do this for mount slew limits?)

 

attachicon.gif Annotation 2019-04-25 113142.png

Ah ha

Ok I have not been doing that

Excellent advice 

Muchos Gracias




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