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I recently upgraded to Level 6 (6.02) and decided to run new PE measurements and generate a PEC curve. I've run into a toothy/jagged PE measurement. I had this issue before with L5 and the solution for this was to adjust ADU values for the star used for the measurement. It is not working in this case. I am using the latest version available of PEMPro (v3.10.07).?

Things I attempted:?
Adjust exposure above and below 2 minutes (images below are from 0.5 seconds and show the same pattern as they do at 2 seconds)
Choose Losmandy G11 rather than Gemini 4/5/6 as the mount type
Choose worm cycles at 2x and 1x within Gemini.?
Adjusted ADU minimum ADU values as low as 3,000 and maximums as high as 20,000 (5000 for low and 15,000 for high had been original settings)

I ran calibration wizard though settings and angles are unchanged from my previous successful measurements.?

Considering the work that went into getting PEMPro v3 functional for L6, I suspect something related to user error (v2.0) is going on here.?

An interesting side note, I loaded my old PEMPro-generated PEC curve into Level 6 and have run it for two sessions since updating from L5 to L6. These have been my two best guided sessions ever with this mount. Admittedly, two sessions do not equal evidence of better real-world guiding performance with L6 since there are so many variables that can influence guiding. They are still well within the realm of coincidence, but it is a coincidence that I am liking.?

George

Your guide star is overexposed and saturates the sensor pixels. Try shorter exposures, no binning, or find a dimmer star.

On Thu, Jun 13, 2024 at 11:03 PM, Paul Kanevsky wrote:

Your guide star is overexposed and saturates the sensor pixels. Try shorter exposures, no binning, or find a dimmer star.

An easier way is to tell PEMPro not to pick such over-exposed stars. Set maximum level to 20000 for your sensor to avoid picking saturated or nearly-saturated stars (32767 adu in your case):

Interesting. I had set the maximum star brightness at 20,000 at one point and then worked my way lower from there. Most of my attempts had been with a maximum star brightness of 15,000. Would this be an issue with default or global gain settings in the camera itself? I can this value in the log, with all readings over 24,000. Given the steps I take before beginning a run, I am likely to have set the camera (ZWO ASI533MM) to a high gain value to focus with a Bahtinov mask and then immediately closed it and opened it within PEMPro.?

George

Sure, try to lower camera gain. The PEMPro screen shots you posted show that the star it was using was at or very close to 32767 adu value. The fact that it didn't vary much between exposures is a good sign the star was saturating the sensor. When doing captures, try to keep these values closer to 20,000 and make sure the values vary between exposures, even if only by few adu's:

Hi George,

Interesting. I had set the maximum star brightness at 20,000 at one point and then worked my way lower from
there. Most of my attempts had been with a maximum star brightness of 15,000. Would this be an issue with
default or global gain settings in the camera itself? I can this value in the log, with all readings over 24,000. Given
the steps I take before beginning a run, I am likely to have set the camera (ZWO ASI533MM) to a high gain value
to focus with a Bahtinov mask and then immediately closed it and opened it within PEMPro.

It could have been that the selected star was temporarily dimmed by a cloud or wind spreading the star out over a wider area.

-Ray

Thanks for the useful tips Paul. This will be helpful to those of us buying and running PEMPro and L6.?

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astrospheric Weather Forecast - South Pasadena, CA?