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Old 09-09-2020, 08:01 AM
Dazzled by the Cosmos.

Dennis is offline
Join Date: May 2005
Location: Brisbane
Posts: 11,132
Originally Posted by Placidus View Post

Could you explain what the different thumbnails are? Are they "before and after fixing the focusing issue", or are they "early, middle, and late night" to show there's no shift, or are they different processing, or as Ellery Queen said, "someone else entirely"?

Perhaps you could give the different thumbs explanatory names, or perhaps you could put captions on them.

I'm assuming that the idea of the near-infrared filtered image for luminance is to take advantage of improved seeing in the near infrared. If so, perhaps you could edit your post accordingly.

Regardless, any single one of them looks magnificent. Well done!

We have a 20 inch PlaneWave, with their three inch throat focuser, carrying about 20 kgs of FLI PL16803 camera, 8 position 50 mm square filter wheel, off axis guider, guide camera, and lots of power and data cables. As supplied, that flops about all over the place, with gross camera tilt as the scope tracks in RA, and resultant marked change in focus. We added a radially placed spring-loaded strut (think of a car's front suspension) so that the focuser can still move in and out +/- a couple millimeters, but is constrained in the RA direction to stay exactly on-axis. That was chalk and cheese. The key point is that the focuser wasn't moving in and out, it was flopping sideways. (The attached photo shows an earlier version with an Aspen camera. The new camera is heavier and the strut system much stronger again).
Hi Mike & Trish

Thanks for looking and commenting, I appreciate it.

I guess I got too excited with fixing my focus drift problem and newly acquired PixInsight skills that I assumed everyone on IIS would know about Steve Crouch's co-discovery of a faint GC.

Here is an inventory of the frames:
  • #1 is a slight crop of the FOV with the ragged stacking edges cropped.
  • #2 through #4 are just tighter crops of UKS-1 showing how small and faint this sucker is.
  • #5 and #6 are full res crops of the region around UKS-1 and Steve's VVV GL001, rotated 90 deg CCW to frame them better.

The IR807 Filter data revealed the GC's - nothing shows up on the LRGB frames so these GCs only reveal their presence in the IR region.

I did try IR642 and not much showed up, but IR742 did begin to reveal some fuzzy data on UKS-1, with the strongest signal in IR807.

It was so satisfying to have finally solved my focus drift problems and to take a deeper dive into PI - it is such a breathtakingly adept image processing tool, or set of tools.


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