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Trapezium E & F with 100mm and other delights

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16 hours ago, Captain Magenta said:

... went out again after dinner and the seeing was considerably less bad. Bagged them both immediately. The E much clearer to me than the  F but no doubt about both. Spent quite a while on them and moved briefly on to Mars and the moon both of which confirmed the seeing was still far from good. Very pleased though.

Nice one, glad you've seen them at last... lovely aren't they 😀

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Just a short session tonight with the 100mm refractor. Mars was hard work to be frank. Mediocre seeing, small disk plus a cold night with heating plumes abounding took their toll so it was only r

... went out again after dinner and the seeing was considerably less bad. Bagged them both immediately. The E much clearer to me than the  F but no doubt about both. Spent quite a while on them and mo

I’ve tried to see them in an 80mm ED, Mak127, C5 & ST120... nothing. Second time out on M42 with the 10” dob and there they were, clear and repeatedly obvious (swapping between 14mm eyepieces).

On 03/01/2021 at 00:52, Pixies said:

Had a shot tonight, while waiting for the moon to appear over the rooftops. The seeing was pretty poor, though. 8" dob.

I think I was getting the E star. Between x100 and x150 something was shimmering in and out with averted vision. The poor seeing made everything tricky; focusing was problematic, especially using the zoom lens. I'd like to try again on a better night. If what I thought I was seeing appears steadily then, I'll say I saw it tonight. No sign of F at all.

Alnitak was a pulsating blob and no hope of splitting anything.

The moon appeared and simultaneously so did the clouds, so back inside now with a nice Rioja.

Had another shot tonight, with much more success.

The seeing was ok once I avoided observing over the nearby rooftops. Transparency was very poor though: the sky looked like there was a bright moon. It's pretty cold and I think there must be some high level haze. 

Anyway, it turns out I had seen the E star. But tonight it was obvious, especially around 100x. No sign of F though.

I also managed to split (notch) Alnitak. It looked like a snowman (or perhaps BB8) with a bright white body and smaller golden head. I confirmed I wasn't seeing things by making a note of the position and later checking on SkySafari, which agreed with my observation. This was at x150. I didn;t fancy messing about with orthos or a barlow in the cold air, so left it at that.

Managed to get a faint smudge for M1, using a UHC filter. Not a great view, though, as the sky was so washed out.

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Happy to be able to report Orion and neighboring goodies is back in my view above the tree tops again.

Had a really wonderful evening in warm, still conditions with excellent seeing. Got straight onto Rigel to see if my 12 inch SW Dob was well collimated and was pleased to see that it was spot on with a star test. Rigel B was easily seen but then again it always is for me.

Okay, if we're well set up lets go for E and F in the Trapezium. Started with the Baader zoom on 8mm (187.5x ), E was seen straight away and F was on and off.

Next in with the 5mm SW Planetary (300x ), both E and F visible all the time, F a bit faint but always there.

Decided to up the magnification with the 4mm Vixen SLV (375x ), both visible but brighter stars tend to get a bit fuzzy at these mags in the Dob and A and C were drowning out the much dimmer E and F.

So, looking for the "sweet spot" I went for my trusty Baader Morpheus 6.5mm ( 230x ), and - WOW! absolutely crystal clear E and F, no shimmering or disappearing at all, just sharp and steady, a beautiful sight.

So, given great steady seeing conditions I can conclude that somewhere around 230x magnification is ideal for spotting E and F, in a 12 inch Dob and the Morpheus 6.5mm really showed its class. 😀


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I think you've touched on the real key to seeing E & F Geoff. It really down to the steady seeing conditions. I've found that even mild turbulence can wash out F, but both are dependant on a relatively steady atmosphere, so it seems that success is more to do with seeing conditions than aperture. I only saw them once in my FS128 yet I have seen them many times in my FC100DC. May be the smaller aperture of the FC is less sensitive to atmospheric temperament?

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