GaryQ where in the text guide log would I find out why I have such deviations as displayed
in the graph log
In your guide log, you will find a line that is like this:
Frame,Time,mount,dx,dy,RARawDistance,DECRawDistance,RAGuideDistance,DECGuideDistance,RADuration,RADirection,DECDuration,DECDirection,XStep,YStep,StarMass,SNR,ErrorCode
Since the line above is so long, it is actually very easy to spot it in a text editor :-).
This very long line tells you that the first column is the frame count, the second column is the time, then mount name, the dx and dy, etc.
For a detail expanation for each colum, look for the section on "Calibration Columns" in
https://openphdguiding.org/PHD2_User_Guide.pdf
Notice that x and y (and xstep and ystep, etc) are pixel coordinates of a star in the guide sensor. RA and Declination are what they say, and are aligned to the sky's coordinates.
This is why I try to always rotate my guide camera angle so that one of the axis of the sensor is parallel to the declination plate. This way RA will be in the same direction as the x direction (or y direction) of the sensor. It makes diagnosing and studying guide problems to be so much easier.
Part of making guide calibration is to find that camera angle. You may remember seeing red and blue vectors (and when meridian flipped, the blue vector reverses direction) that are at right angles to one another (if you calibrate at the celestial equator), but the red/blue vectors can appear rotated from the horizontal and vertical axes by the guide camera angle.
Chen
