Messier 101 was unplanned

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Pete
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Messier 101 was unplanned

Unread post by Pete »

Tuesday, 10 May 2022

25 – 35 mph wind for the past two days but it’s dropping a bit. There’s a bright 80% phase moon high in the sky. Not a night for imaging, but it will suffice for testing.

Tonight’s objective is to determine whether it’s feasible to use my customized f/6.3 focal reducer with the 14” and the C sized camera chip. The focal reducer had vignetting with the smaller SBIG camera chip and I’m not optimistic. But the bloated stars at prime focus are bad, and I’m ready to try anything.

The refined lower shutter is mounted and the dome shutter is not fully retracted, so that neither neighborhood lights or moonlight reach the telescope. The monitor hood has been refurbished and is also in use to minimize interior light levels.

Out at 20:05. It’s 52°F. Centered Arcturus and focused with present setup. Then installed the FR into the image train and refocused. Ran 60 one-second flats and there’s obvious vignetting. The flat spectrum is odd, with R being very dim and B & G being very bright. All three histograms are oddly shaped and dragging toward the low end. Also ran dark flats as I’ve come to believe that they’re critical. Flats exhibit definite vignetting.

The test object is M101.
M101 81X3m 8x11 s.jpg
M101 81X3m 8x11 s.jpg (945.27 KiB) Viewed 438 times
14” Meade LX200 GPS with LP-Pro filter, f/6.3 focal reducer and ASI2600MC-P camera
81 X 3 min, 2X binning, -10C cooling, 120 gain, 5 sec guiding.

In at 01:08. Temperature’s only fallen to 46F.

Conclusions, observations and lessons learned:

Prior to post processing the quality of all individual frames was checked, and I found that detail improved significantly once the moon started setting. Toward the end of the night the galaxy became easily visible in the individual frames. Obviously even with the filter LP noise is significant and for best results I should have waited until the moon was down. Except that this was a test and I didn’t expect to wind up imaging.

This image is better than the 3-hour M101 imaged 6/7/21 on a moonless night without the filter or focal reducer. And I was satisfied back then. So it’s coming together.
Pete P.
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NGC7000
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Re: Messier 101 was unplanned

Unread post by NGC7000 »

Wow! That is a startling good image, Pete. I didn't expect to see THAT result. I enjoyed the narrative. Apparently, it really does pay off to wait out the Moon.

Tom
Tom H
"Science knows no country, because knowledge belongs to humanity, and is the torch which illuminates the world. Science is the highest personification of the nation because that nation will remain the first which carries the furthest the works of thought and intelligence." - Louis Pasteur
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menardre
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Re: Messier 101 was unplanned

Unread post by menardre »

I agree with Tom.. really nice image of M101..especially considering the conditions.

I decided not to do any imaging due to high winds. Instead I spent time testing my setup for the up-coming lunar eclipse.

Roger
Roger M.
Celestron CPC1100 EDGE, Stellarvue 130T refractor dual mounted on iOptron CEM120 on permanent pier mounted in Observatory. Imaging camera ZWO ASI2600 OSC, guide camera Lodestar or ZWO ASI290MM.
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