Optimal PHD calibration at start up or after camera rotation

Since PHD2 Is most ideally calibrated near Dec=0, and since there is already an option to force PHD recalibration when changing targets, is it possible to make provisions for an optional slew to optimal coordinates prior to the calibration? Sort of reminiscent of skewing away to a bright star for focus then returning to the target?

In addition to the initial calibration, this feature would be useful to users of a Manual Rotator with OAGs who need to recalibrate after a successful camera rotation.

Along these lines, it would be nice to have the option to force a recalibration after a rotation is completed, as differentiated from forcing a recalibration after every target change. I think that this isn’t required for an actual, physical rotator (since the parameters can be passed to PHD), but for a manual rotator, a recalibration is always requires if an actual rotation is done.

Thanks for consideration and best regards,

Hi Craig,

Since SGPro require mounts to be ASCOM capable, that means your mount’s ASCOM driver may be likely to be capable of ASCOM pulse guiding. If you opt for ASCOM pulse guiding in PHD2, you do not need to worry about flipping calibration data in PHD2 after Meridian Flip because PHD2 will automatically take care of it since it reads data from your mount via ASCOM driver and checks for side of pier. No need to re-do calibration when using ASCOM pulse guiding.

Even if you change targets, PHD2 will automatically handle autoguiding and no need to re-do calibration if ASCOM guiding is used. PHD2 automatically reads new Declination coordinates of new target and make necessary adjustments for autoguiding.

But if you do Meridian Flip and rotate the camera, then I believe you will need to re-do calibration. But there’s usually no need to rotate the camera since many stacking software automatically handles it. Also, you will likely need to take flats before and after rotating the camera and that can be a pain and defeats the purpose of automation.


Hi Peter,

I agree with all your points, and thanks for letting me further clarify

This opportunity isn’t so much about a meridian flip… I am successfully doing that. It is specifically applicable if using an off-axis (or integrated) guider. It is about specific camera rotations for framing purposes, and somewhat about the initial calibration as well.

As you point out, PHD2 can account for different declinations, but to do its best job at those corrections, it is suggested to calibrate at Declination near zero. It’s because of this capability that it would be nice to force a calibration only after a camera rotation and not after every target change.

Also, I recognize that the process isn’t really automated if I’m employing a "manual “rotator,” but it is also a helpful reminder that a calibration is required after rotation

I appreciate the input!


Another possible solution would be if SGP exposed the angle of the manual rotator to PHD2 by implementing a rotator ASCOM device for the manual rotator. That way you would not need to reacalibrate at all! Just a thought…


Hi Craig,

I saw your profile and noticed that we both own awesome A-P1100GTO mounts. You will love the mount and SGPro works fantastic with this mount. You can see my setup at:

Click on “Telescope” and then “Current Equipment”. Feel free to browse my DSO images (latest images sorted first). I find A-P mounts pretty easy to operate.

Enjoy your new mount (I read your very well written blog). Feel free to send me PM if you have any questions with the mount as well as SGP controlling the mount.


@Andy, that would certainly work for me…

@topboxman, we are even more alike now… I had forgotten I posted a profile; it’s now updated to reflect the fact that I swapped my FSQ106 for a TEC140. My camera is still red, though, but it is now the STT8300. Thanks for the nice comment and generous offer of support. Feel free to reach out to me as well, and if I can help, I will.


Wow, that’s another thing we have in common. We both have TEC 140 scope!!!


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@kenpendlebury, just curious… Do feature requests like this one eventually get categorized one way or another?

It’s hard for me to tell if it is not a worthwhile feature (which is fine) or if it may have been either unnoticed or lost in the shuffle?

Thanks a bunch,

Yes. Every few months. It would be a disservice to do it often. The idea is
to let them sit and be voted on to determine popularity. Usually 2-3
months. We are behind a bit to. The amount of help requests for 2.4.x has
been way higher than normal. This is one more reason we are being careful
about what we add… Everything has a cost in support.

Thanks for the clarification.


Categorizing this under accepted unplanned. I do not wish to add the complexity of more options required to support this… I actually even want to remove the “Recalibrate on target change” option, but I think this is required for folks that still like to use ST-4 (I’m not sure why you would want to do this). @Andy can correct me if I’m wrong here. This request, while understandable, based on its popularity does not affect many folks. Adding a simple ASCOM driver for an “SGPro Manual Rotator” would allow PHD2 to make all these adjustments for you and not complicate the process even one little bit for folks not interested in this.

Moving this to 2.5.X

That sounds like a great approach.