RA-Only Guiding on a Star Adventurer with Camera mounted to RA axis ala POLESTAR

[S Eigell]

I've got a Star Adventurer EQ Mount, to which I'm thinking to add my ASI120. The Mount is driven RA-Only, with an ST-4 Port and a convenient Camera mounting position along the Dovetail (meaning parallel to the RA Axis ana pointed at the NCP ala Polemaster). I could add a Side-by-side Mount, or a 2nd Ball-head Mount, in order to point the GuideCam in the same direction as the Imaging Rig. But that is a significant portion of the Usable Payload that I'd rather save.

I normally Image with a DSLR and 180mm NIKKOR f/2.8 ED, or now an ASI1600MM-Cool with an EOS Lens Mount - so its all relatively Widefield. But also desirable to Dither.

Now how does PHD2.6.3:
1) Perform Calibration or GA or Drift on an RA-Only Mount??
2) Guide with a Camera pointed at NCP??
3) Dither in RA-Only??

TIA,
seigell

[Brian Valente]

Regarding 3. PHD2 has an RA-only dither option

Thanks

Brian


Brian Valente
Brianvalentephotography.com

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[Andy Galasso]

... and regarding 1 and 2:

Calibration, GA, and Drift alignment should all work fine on your RA-Only Mount; just be sure to set your Dec Guide Mode to None. Calibrating near the pole may be a little tricky. Use the calibration step size calculator to determine the calibration step size you will need. Another option would be to use the Aux Mount = "Ask for coordinates", then you can calibrate away from the pole (like near declination 0.)

Guiding with the camera pointed near the pole should not be a problem. But if the pole is actually in you guider FOV, that probably won't work since PHD2 won't know how to correct the guide star motion -- unless you calibrated on the same star that you are guiding on.

Andy