Can anyone identify this weird mottling?

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psy1280
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Can anyone identify this weird mottling?

#1

Post by psy1280 »


I’ve never encounter this weird kind of mottling before—no idea what it is???


After many years with my trusty SCT, I recently purchased an ASKAR FRA600 from a friend (my first refractor).


Notes:
* I was taking 3 minute exposures using the ASIAIR+. The images on the ASIAIR screen seemed “normal.” Total intergration time was 7 hours.
* My only filter was an UV/IR cut filter attached next to the camera (ASI 294 MC pro).
* Guiding was fine
* I’ve run the stack of FITS light files through APP (three times) see attached image.
* Flats, Darks, and Dark Flats were used
* no moon
* I was imaging at the Fra600’s native 600 mm
* The jpg images that were saved all show this weird mottling (even the saved jpg images in the ASIAIR folder)(the lights I used for stacking were only FITS files)
* Camera was cooled to -10C


* Previously, there were no problems the few times I used the focal reducer with this telescope (i.e., problem seems to be with capturing not the scope)

I have never encountered this problem before and would appreciate any and all thoughts/speculations, etc.


APP image.jpg
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Gordon United States of America
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Re: Can anyone identify this weird mottling?

#2

Post by Gordon »


I get similar mottling with my ES80ed and my ASI553mc-pro.

It processed out with darks / flats and darkflats. I'm curious now why yours didn't.

Lets see if anyone has any ideas.
Gordon
Scopes: Explore Scientific ED80CF, Skywatcher 200 Quattro Imaging Newt, SeeStar S50 for EAA.
Mounts: Orion Atlas EQ-g mount & Skywatcher EQ5 Pro.
ZWO mini guider.
Image cameras: ZWO ASI1600 MM Cool, ZWO ASI533mc-Pro, ZWO ASI174mm-C (for use with my Quark chromosphere), ZWO ASI120MC
Filters: LRGB, Ha 7nm, O-III 7nm, S-II 7nm
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Primary software: Cartes du Ciel, N.I.N.A, StarTools V1.4.

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psy1280
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Re: Can anyone identify this weird mottling?

#3

Post by psy1280 »


Thank you Gordon...it's a mystery, especially since a few weeks ago with the same set up, everything was fine
psy1280
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Re: Can anyone identify this weird mottling?

#4

Post by psy1280 »


Just wondering, could this be caused by my forgetting to turn on my camera’s cooler? I can’t recall, but that would also have affected the flats and dark flats.
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Re: Can anyone identify this weird mottling?

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Post by Juno16 »


You could check the fits header for a sub to check camera temperature.
Jim

Scopes: Explore Scientific ED102 APO, Sharpstar 61 EDPH II APO, Samyang 135 F2 (still on the Nikon).
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Re: Can anyone identify this weird mottling?

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Post by JayTee »


psy1280 wrote: Thu Feb 16, 2023 2:27 pm Just wondering, could this be caused by my forgetting to turn on my camera’s cooler? I can’t recall, but that would also have affected the flats and dark flats.
Absolutely. The mottling you have does look like heat noise. I know about this because I used to image in Hawaii. My sensor temps ran between 95° to 110°F. And I had to deal with heat noise all the time.
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
∞ Mounts: iOptron CEM70AG, SW EQ6, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000
∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3
∞ Binos: 10X50,11X70,15X70, 25X100
∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°

Searching the skies since 1966. "I never met a scope I didn't want to keep."

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