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Location of Photo:

Julian, CA

Date/Time of photo:

February 15, 16, 18, 20 2023


Planewave CDK24 w/L600


The winter months in Julian CA are a real challenge. I needed an object that would stay up most of the night. NGC 2634 was the choice. It would be above 30° between 7:30 PM and 4:30 AM (9 hours) with the sky between 21.0 and 21.3 SQM for the entire 9 hours. For this I switched from the ASI6200 CMOS back to the FLI16803 CCD for a wider FOV. As I mentioned in prior posts, 15 minute exposures on the 16803 have nearly the same SNR as 5 minute exposures on the 6200. But it seems the 16803 might go deeper. Maybe the microlenses help in that regard. Seeing is usually horrible during the winter months, and this year was no different with seeing (FWHM) near 5". I usually see < 2". On February 15, I was able to capture 20 L subs (5 hours) between 3" and 3.3". Not too bad. February 17 was too windy to shoot. The CDK24 moves noticeably in 5-10 MPH winds. This was 15 MPH+. The wind died down on February 18 just enough to capture 2 hours of each RGB. But FWHM was near 5". This would cause halos around the bright stars that would be difficult to correct. A very large storm was expected to arrive on the 21st (which is did and is still here). So this could be a bust. THEN, February 20, the day before the storm, everything became eerily dark, quiet and STEADY. FMHW now between 2" and 3"!!! For 9 hours, I captured 5 hours of L and 1:45 of each RGB. I discarded the prior 5" RGB and added the new 2" L to the prior 3" L. So 10 hours of L and 1:45 of each RGB for a total of 15:15 of subs with an average FWHM of 2.5" in a 21.0 to 21.3 SQM sky. THE CALM BEFORE THE STORM.