Hi Ray,

I have been having some PEC data acquistion issues and I just want to eliminate some possible sources of problems.

First, to understand drift better, looking at the PEMPro graph area the X axis is time and the Y axis is azimuth drift or PE error - correct? So, after acquiring data and you check the adjust for X or Y what is PEMPro actually adjusting from the mount standpoint?

My understanding is the DEC or altitiude has nothing to do with the graph - correct? And that the Y axis = RA PEC data, or, RA drift (azimuth only), or tracking. Therefore if the start and end of the run does not match-up then either the RA drift or tracking are not accurate (again DEC misalignment has no effect on the data)?

Also, have you received any reports of corrupt .txt files? I have had some cases where I acquired 24 min of data and the graph looked like a nice sine wave however the saved .txt file looks like the attachment - not sure what is causing this for me...

Thanks for the help!

Kurt

PemPro-2009-08-25-012927_2nd_run.txt (12 KB, 15 downloads)

Hi Kurt,

quote:

First, to understand drift better, looking at the PEMPro graph area the X axis is time and the Y axis is azimuth drift or PE error - correct? So, after acquiring data and you check the adjust for X or Y what is PEMPro actually adjusting from the mount standpoint?

Depending on the view mode, the display is

1) worm phase (X-axis) versus arc-secs or pixels (Y-Axis).
2) Time(X) versus arc-secs or pixels (y-axis)

Adjust for X/Y do nothing but remove drift from the *graph*. It has no effect on the data with respect to programming the mount. drift is removed at the create PEC step.

quote:

My understanding is the DEC or altitiude has nothing to do with the graph - correct?

It might if you didn't do the calibration wizard and/or have "Y-axis" selected in PEMPro. Doing the calibration wizard calculates the derotation angle and if you have "Derotate" enabled in the Settings menu of PEMPro (the default) then the X axis is RA and the Y axis is declination.

quote:

And that the Y axis = RA PEC data, or, RA drift (azimuth only), or tracking. Therefore if the start and end of the run does not match-up then either the RA drift or tracking are not accurate (again DEC misalignment has no effect on the data)?

Yes, if the cycles drift upward or downward with Adjust X/Y off then that is simple RA drift (from tracking, polar alignment, or flexures issues, etc.).

quote:

Also, have you received any reports of corrupt .txt files? I have had some cases where I acquired 24 min of data and the graph looked like a nice sine wave however the saved .txt file looks like the attachment - not sure what is causing this for me...

Nope, no reports. The data will appear to have gaps if the star is lost (maybe from a cloud) or too faint a star.

-Ray

Thanks Ray,

I might be more confused now, first answer is unclear since worm phase is expressed in minutes - so 1 & 2 are both time?

Also, I always do the calibration wizard and have derotate checked in settings. The RA axis is selected as X axis - so this means the Y axis is RA PE and DEC is not a factor - correct?

Last, the cycle drfits up and down with x/y off so it must only be the azimuth polar alignment or tracking (not DEC alignment) effecting the graph not meeting endpoints?

Thanks

Kurt

Kurt,

quote:

I might be more confused now, first answer is unclear since worm phase is expressed in minutes - so 1 & 2 are both time?

Yes. Maybe if you load a curve and press F11 you will see better what I meant. You will see all cycles displayed after you press F11. Press F11 again and you will see the cycles wrap over the periodic of the worm cycle.

quote:

Also, I always do the calibration wizard and have derotate checked in settings. The RA axis is selected as X axis - so this means the Y axis is RA PE and DEC is not a factor - correct?

Yes, that is correct.

quote:

Last, the cycle drfits up and down with x/y off so it must only be the azimuth polar alignment or tracking (not DEC alignment) effecting the graph not meeting endpoints?

No, unfortunately you cannot tell from the drift what might be causing the RA tracking error. In fact if you are acquiring PE data near the meridian then RA tracking is not much affected by polar misalignment.

-Ray