Messier 20 - the Trifid Nebula

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Pete
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Joined: Fri Jun 13, 2003 9:03 pm

Messier 20 - the Trifid Nebula

Unread post by Pete »

Wednesday, 3 Aug 2022

Things seem to be clicking with my recent imaging. Tonight’s clear, calm, and the moon is setting. Got a half-dozen possible targets selected but I’ve got a very rare shot at M20.

There’s a small 2-hour window where it clears trees around 21:15 and leaves the gap in the horizon around 23:00. Timing is perfect.
The Trifid is relatively bright and 3 minute exposures work for the 102mm triplet. The observatory interior is kept darkened, even shielding or covering the two computer screens.
M20 s.jpg
M20 s.jpg (913.24 KiB) Viewed 375 times
Wishing Star Observatory Barrington RI USA
21:09 – 00:23 hours July 30 – 31, 2022
39 X 3 minutes (with 24 frames subsequently discarded) unbinned, -5C, 120 gain, 1 sec guiding.
Explore Scientific 102mm triplet with Optolong LP-pro filter and ASI 2600MC-P camera

Early in the imaging sequence the guide star was creeping out of the bottom of the PHD2 highlighted square. The pier may have settled in the 16 years I first aligned it, and this may be why a slight drift occurs. But in this case the drift was heading out of the box. So I stopped the guiding and reselected the star so as to center it. Unfortunately instead of hitting “enter” I hit “shift enter” and the scope went into another calibration cycle rather than simply resumed guiding.

Didn’t note what frame I was at but this may be the reason that guiding went bad. 24 of the captured frames had stars that were elongated at an angle of approximately 120° and the problem started at frame 13, which is approximately the point where I’d screwed up the guiding. So there were only 15 clean frames. Which is a shame because the full stack shows lovely nebulosity in the bottom L and R of the image, whereas in this image there’s only a hint of the nebulosity.

In at 23:33 hrs. It’s 74°F.

Analysis:

Printing this image, it’s not bad. Could be much better but it's not bad. And that’s my success/failure criterion. That’s a surprise, with only 45 minutes total usable exposure. Sadly, the full 39 frame stack displayed lovely clean nebulosity. Water over the damn dam.

Much better than anticipated as M20 was only 23° above the horizon. I normally won't touch anything less than 30° high.

Next priority is to do a new drift align on the mount. That’s what moonlit nights are for, right?
Pete P.
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menardre
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Joined: Tue Jan 17, 2012 6:09 pm

Re: Messier 20 - the Trifid Nebula

Unread post by menardre »

Pete

You are awfully hard on yourself.

I think this image is a lot better than 'not bad'.

Colors are vibrant and stars are pi-point. I would have been happy with the result

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.
Bruce D
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Joined: Sat Jun 14, 2003 6:10 am

Re: Messier 20 - the Trifid Nebula

Unread post by Bruce D »

That's an awesome image Pete, motivates me to give the Trifid another try when I get the gear out in a few weeks, well done!
Bruce D
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