Hi folks,
recently i had the occasion to observe at altitude of 5000 ft.
Air humidity around 15%. Seeing 2-3. No wind at all, slightly brightened sky yet - not perfectly dark. NELM around 7m0, maybe slightly worse. To describe conditions a bit more: M 81 has immediately shown its two spiral arms - without any struggle, in clear shape - i never saw these spiral arms like that before, having > 10 years of alpine observation experience with 12".
I gave the cone nebula a try and want to share with you my results with 12". For better description i marked a pic shot bei the ESO as seen below.
cone nebulae_ESO_12inch_description.jpg
The numbered features with description of their appearance/ visibility as follows, main observation with 12,5mm, followed by 17,5mm - with no clear advantage for one or the other for detecting details:
1: this little cap appears quite soon with averted vision and not too much effort. Already one night before with 25% air humidity it has been visible but rather pointlike as far as i remember. Under better transparancy with 15% air humidity and a bit of patience it really is a little ellipsoid cap just like in the picture. I am very sure that this is the bright end of the nebulae itself an not the stars within. I could detect a glow at the right spot in all used eypieces - 26mm (52x), 17,5mm (77x), 12,5mm (109x).
2: Later on after trying to perceive anything of the edges (results below) i decided to take a specific detail into view, to try to get a glimpse of it. I am not completely sure for i could not repeat it as far as i remember - but at one time at the right spot a little smudge appeared for a short moment. I had been quite exhausted by that observation already, otherwise i had tried longer for further glimpses.
3: Order of numbers is not that of my observation, so my attempts to see the entire edges was before having a look at a pic. When i thought having catched an edge, it always was very hard to distinguish from some kind of illusion. Yet, in one moment i believed to see a little curvy brigthening at the end of the supposed edge. Again: without knowing about the real shape of the cone nebulae and that there is this very feature.
4: Repeatidly i had a slight, very slight "illusion" that there could be an edge. The bright star at the end is very very disturbing. You can never know, what kind of contrast effects give the illusion of an edge... So in the end i wouldn´t say that i saw an edge.
5: Contradictory to point Nr. 4 i shortly, very shortly, really had the impression of a thick dark longish gap in a fleeting moment. But i could not repeat it so i classify it as unseen. However, i want to add this surprising moment as part of my observation - real feature or not.
To sum it up - this little cap in Nr. 1 is easily visible with an aperture of 12", good transparency given. For anything more i also see chances - but for a real positive observation i will give it a try again when conditions allow.
Would love to read from results with similar aperture.
CS!
Norman
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