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  #1  
Old 26-08-2018, 11:57 AM
Startrek (Martin)
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Running Stellarium concurrently with PHD2

Iím about to start using PHD2 soon so wanted to know if I can run my planetarium goto program ( Stellarium ) concurrently with PHD2 as there is only 1 com port allocated
Obviously I would select an object , slew to it and start tracking ,connect PHD2 select a guide star , calibrate and then start guiding
Iím concerned PHD2 wonít connect through Ascom to the mount if Stellarium is connected to the scope via EQMOD and StellariumScope ( only 1 com port )
Havenít tried it yet but wanted some advice and personal experience
I realise that PHD2 will not guide unless you are locked on the object and a guide star is selected

Appreciate any advise on the subject

Thanks
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  #2  
Old 26-08-2018, 12:55 PM
Imme (Jon)
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I do similar with APT.
I select an object, APT slews to it then platesolves and then i start guiding. Both programs are connected together.
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  #3  
Old 27-08-2018, 05:51 PM
kosborn (Kevin)
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Each program will talk to the ASCOM driver which then talks to the COM port. The only thing that will happen if Stelllarium slews to a target while PHD2 is tracking is that PHD2 will complain it has lost the guide star. I have PHD2, SGPro and Astrotortilla all talking to my mount without any conflicts.


Kevin
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  #4  
Old 27-08-2018, 07:59 PM
Startrek (Martin)
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When I use Stellarium to find and lock onto an object itís uses Stellarium scope to find the mount , connect to the mount via EQmod Ascom and provide slew, stop and sync commands
But before you can connect to the mount via StellariumScope you have to set EQMOD Ascom with your mount type , port details, site location information, and guiding information which is pulse guiding
In eqascom you have to set your tracking rate, site location information and alignment type and this will enable your goto via StellariumScope in Stellarium
My question is do I have to set any pulse guiding parameters in EQ Ascom EQ5/6 to enable PHD2 to guide correctly or does it just run with the nominated tracking rate and guide according to the selected guide star in the field

Iím a bit lost , Iím trying to get my head around your planetarium software tracking an object at say sidereal rate and PHD2 guiding with micro tweaks to correct the errors

Appreciate a simplistic explanation
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  #5  
Old 27-08-2018, 10:36 PM
kosborn (Kevin)
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A couple of things to clarify the problem.

Although Stellarium shows sidereal motion in it's display it doesn't send tracking information to the mount. If you select an object in Stellarium you can (via Stellarium Scope) instruct the ASCOM (EQMOD) driver to tell the mount to slew to that object. It's only when you press a key combination (such as Ctrl-1) that Stellarium instructs the mount to slew. It will continuously read mount position and plot that in the display but will not send tracking information to the mount.

As you pointed out, EQMOD has various tracking rates including sidereal, lunar and solar and for DSO targets, sidereal is needed. Assuming you select sidereal and then start PHD2 guiding, PHD will not change the tracking rate but will instead make small adjustments (via ASCOM) to the RA and Dec positions to ensure your selected tracking star stays in the correct position of your guide camera and therefore your mount will accurately track your selected DSO. Obviously, if you are using PHD to follow a star (which must be moving at sidereal rate) it would make no sense to have your mount tracking at any rate other than sidereal.

You can effectively treat all of the programs as independent, all talking separately via ASCOM to the mount. Accurate goto in Stellarium depends on accurate polar alignment of the mount and accurate site location and date/time set in EQMOD and separately in Stellarium - usually supplemented by a star alignment routine with your mount's hand controller or with plate solving.


Kevin
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  #6  
Old 28-08-2018, 06:06 AM
Startrek (Martin)
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Thanks Kevin for clarifying
So all I have to worry about in EQMOD is set the tracking rate correctly and PHD2 will take care of guiding once the object is found and centred in Stellarium and a star in the object field is locked on and calibrated etc then start guiding and monitoring

Next clear night when Iím free I will set up and try to guide

Thanks again
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  #7  
Old 28-08-2018, 08:02 AM
kosborn (Kevin)
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Yes, the steps I do each night after connecting, powering up, starting programs etc are:
  1. Use Stellarium to slew to a star (any star) near the celestial equator and just off the meridian.
  2. Drift align with PHD for azimuth alignment (I don't usually do alt alignment because I have that fixed on my mount).
  3. Use Stellarium to slew to target.
  4. Use Astrotortilla to plate solve and center target.
  5. Start tracking with PHD2.
  6. Start acquiring with SGPro.
A couple of things could be done differently. Your handset will allow a star alignment routine for accuracy with goto. I don't do that because I use plate solving with astrotortilla and each time it successfuly plate solves it syncs with and updates the mount. I could use SGPro to slew and plate solve but I like Stellarium and Astrotortilla. SGPro also can start and stop PHD2 so manually starting PHD tracking is not strictly necessary.

Hope that helps. Enjoy your next clear night!


Kevin
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  #8  
Old 28-08-2018, 04:03 PM
Startrek (Martin)
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Thanks Kevin

As I use EQ Direct , laptop straight to mount ( not PC Direct ) with handcontroller disconnected,I use the sync feature in Stellarium to centre my objects , it works as good as a 2 Star alignment with the handcontroller. PC direct mode via the handcontroller with a Keyspan USB serial adapter and driver wouldnít connect for me ( my son has been in IT for 15 years and tried everything ) so I ditched it and went EQ Direct with the shoestring USB custom cable no issues connected first time ( PHD2 recommend EQ Direct with pulse guiding )

Thanks for your advice and information

Much appreciated!

Martin
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