SGP is forcing recalibration for phd2

I’m running SGP and I get an error in guiding at the start of the sequence.

I setup phd2 calibration and guiding without a problem. I stop guiding and start my sequence in SGP. The slewing and plate solving are performed without problems. The guider is started and I get the message “Resuming the auto guider (forcing recalibration)” even though I have the" re-calibrate after target position" unchecked.

Phd2 starts calibration, finishes and starts guiding but SGP comes back with an error of “Auto guider failed to recalibrate and resume! Aborting sequence”.

You can find the log file here:

You can find the SGF File here:

Thank you for your help,

In PHD2 check “Auto restore calibration” on the Guiding tab.

I checked and I have this already checked

I’m still having trouble with PHD2 forcing calibration and I can’t get past this hurdle to make SGP work. I tried using the “SGP Api Guider”, but I get an xsize not defined error in PHD2 when I try to guide.

In addition, I can’t get SGP to recognize my SBIG camera. This is new problem.

I seem to take 1 step forward and 2 steps back.

Are you using a Dual Chip SBIG camera? The API guider will only work with dual chip guiders and must be enabled in the SBIG settings in SGP.

It looks like PHD is recalibrating when you start SGP with this error Calibration was too far from equator, recalibration is needed.

Sounds like PHD is expecting calibration closer to the equator and meridian. Maybe give that a shot and save off that calibration data and see what happens.


Try rebooting the PC and power cycling the camera. Also if you’re attached to the camera in some other application SGP won’t be able to attach. If you have a dual chip camera this also applies to both chips as the SBIG driver structure only allows a single application to access the camera.


Excellent, that explains the mystery of the unwanted calibration! As Jared says, you just need to run a calibration at the recommended calibration location: somewhere near declination zero and away from the horizon (like within a few hours of the meridian.)

PHD2 automatically saves the calibration information each time calibration completes, and you can’t not save it. You have already confirmed that you have the “Auto restore calibration data” option enabled, so PHD2 will restore the calibration automatically for you when you connect the equipment in PHD2.


Jared and Andy,

Thank you for your response and I’m happy to say that the acquisition of the PHD2 calibration at near zero declination has solved the problem.

I’m currently acquiring data on the Heart Nebula and very excited.

Thank you both for solving my problem.


HI Bill, Andy - I had this issue last night - after installing all latest versions of PHD2 and SGP Pro - found your article here - I had similar issue - PHD2 was fine after each calibration but then SGP was saying “resuming the auto guider (forcing calibration)” so I got stuck in a loop where the calibration would fail because of a lost star and I think I un-checked force calibration in SGP or maybe I just got close enough later for it to work. Andy long time no see! Is this a newer feature in PHD2 and does SGP allow us to skip it? - I don’t remember that from years ago and SGP Eq Profile and Sequences is confusing as crap - its like two people had different ideas on where your settings should live. Granted tonight was terrible seeing and setting up a new OAG and just have terrible guiding from mount issues as well - so I lost a night just trying to get ready for what should be better tonight.
clear skies