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INDI Library v1.8.5 Released (19 Apr 2020)

April 2020 release of INDI Library v1.8.5 introduces new drivers while providing fixes and improvements to existing devices and core framework.

Astro-Physics GTOCP4 driver, lx200ap_experimental.cpp

3 months 1 week ago
wildi
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Astro-Physics GTOCP4 driver, lx200ap_experimental.cpp #51592
Hello Jasem

working on thread Advice re Astrophysics Experimental driver I found several glitches which prevented the mount to be parked properly (see attached git diff).

But there is a more fundamental issue. Pointing an equatorial to Az = 0, 180 deg (N/S), Alt = latitude is impossible, since HA (hour angle) is undefined. Any other AltAz position has, of course, a defined HA and Dec value. Since up to now Astro-Physics does not sell any AltAz mounts I think it is best to implement the park positions (1,2,3,4,5) as pairs of HA, Dec. That means replacing any calls of setAPObjectAZ(), setAPObjectAlt() by e.g. Goto(equatorialPos.ra / 15.0, equatorialPos.dec) including the necessary calculations.

If you agree, I'll change the code accordingly in file lx200ap_experimental.cpp and may be in the other AP drivers, too.

Kind regards, bye, wildi
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3 months 1 week ago
ChrisRowland
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Astro-Physics GTOCP4 driver, lx200ap_experimental.cpp #51595
Would the mount axis positions be a better definition of the park positions? While the hour angle at a declination of 90 is undefined the mount axiis positions are still defined.

This depends on the axis positions being available from the mount, ideally both read and move to.

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3 months 6 days ago
mikefulb
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Astro-Physics GTOCP4 driver, lx200ap_experimental.cpp #51613
FWIW the current code will properly park to the park positions defined by AP. Perhaps the problem is simply if this data is saved persistently? I'm not sure any changes to the driver are required other than verifying this aspect. I tested parking via the INDI control panel many many times before getting it to work. :)

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3 months 2 days ago
wildi
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Astro-Physics GTOCP4 driver, lx200ap_experimental.cpp #51795
Hello

I solved this issue and made my fix available as a pull request AP drivers, undefined park position in HA/Dec coordinate system .

Chris, at Dec = +/- 90 deg HA is well defined, e.g. HA = -6 hours means for a GEM that the counter weights are at their lowest position, where observing at HA = 12 is in general only possible if the mount has a Knicksäule .

Kind regards, wildi

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3 months 1 day ago
ChrisRowland
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Astro-Physics GTOCP4 driver, lx200ap_experimental.cpp #51798
I've never heard of a Knicksäule, but the internet came to my help, not with a translation but a photo. It looks like a bent or kinked pier.

I don't see the need. At Ha 0 you can reach an object at a high declination and can track it through Ha 6 to Ha 12, during which time the scope is above the pier so little to get in
the way. Once you track past +12h you are in the same position as tracking past 0h, the scope is tracking under the pier. The solution is to do another meridian flip to put the scope on the east side of the pier so it is now tracking over the pier.

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3 months 1 day ago
Spartacus
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Astro-Physics GTOCP4 driver, lx200ap_experimental.cpp #51809
Hi Mike
I have been working with Wildi and testing the solutions that he is working on.
My original post ("Advice re Astro-Physics experimental driver") a few months ago opened the discussions.
The mount is a AP 1100GTO running GTOCP4 and belongs to my son.
Despite what you say the Park 3 position never worked for my son's set up. The mount always ending up pointing to what, in position, is the same as Park 2. After much time spent trying different approaches my "work around" was starting and finishing in Park 2. So there definitely appeared to be a DEC positioning problem at this Parking point (Park3).
I am no expert and this is not my scope either but as it is now resident at my place I have had the opportunity to try to sort the parking issue.
I too felt it was difficult to define the specific Park 3 in terms of Alt/Az as the HA was not defined.
Unfortunately I don't have the technical expertise that you guys have and my gear uses the EQMod driver.
What I can confirm is that in the set up that we are using (AP 1100GTO and RPi3b) using Wildi's alterations the DEC issue is sorted and it will now Park to the Park 3 position but does require to be unparked from Park 3 rather than last parked for a consistent operation.

From a practical viewpoint I could have continued using Park 2 however it is nice for the driver to work as intended in our setup and I want to thank Wildi for his patience and assistance in walking me through each step.

Hope this helps
Best regards,
Mike

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