Saturday, 26 September 2009

Nebula chasing around Cygnus. And a few other things.

It was again a clear night last night and it turned out to be a pretty good session.

25-26 September 2009. Conditions: Chilly at 8 degrees C (later 6 degrees C), humidity 84%. Seeing Antoniadi scale II-III, transparency II-III. Limiting magnitude 6 to 6.2 later on.
Instruments: 12 inch f/5 Dobsonian and 8x42 binoculars

After the previous night's hassles I didn't bother collimating the scope and, as it turned out, it was slightly out (as expected) but otherwise not too bad.

After the requisite time spent getting dark adapted, I went for a bit of an ambitious first target: Pease 1, the planetary nebula in the Pegasus globular cluster M15. After locating the cluster itself, I put an OIII filter onto the eyepiece, the highest power I could get. I have to admit, that I am not sure if I saw Pease 1 or not. The OIII dims the cluster nicely, but the planetary is a teeny little thing and could have been any one of the stars not dimmed too much by the OIII. I am going to print some decent charts off and have another go at it next time (and when my scope is properly collimated - I have sent off for a new laser collimator today, my Revelation one is totally buggered and refuses to work at all now. I think my hurling it across the garden the other evening has completely finished it off!). Even blinking the filter in and out of the eyepiece didn't really make anything stand out.
M15 itself, as ever was a pleasant sight. Bright condensed core and with many stars resolved. 190x

I gave up on Pease 1 and moved onto brighter things.

NGC 6800 is a nice open cluster in Vulpecula, easy to locate. It is large, loose and irregular. Not bright, stars of uniform brightness. Some of the stars form a circle around the middle of the cluster, but the centre of this circle contains no stars. Nice with the 35mm TV Panoptic (43x). Sketched with the 25mm Plossl (61x).

Next was the Veil Nebula in Cygnus. This is one of my all time favourite objects and tonight I spent over an hour looking at, and sketching, the components NGC 6960, NGC 6992 and NGC 6995 (these last two form a large loop).

NGC 6960 is the western portion of the Veil and is visible without a filter but UHC brings it out nicely. However, OIII gives the best view and the nebulosity looks fatter and more detailed with the OIII. It looks like a witches broom (in fact I think 'Witches Broom' is a nickname for it) with a bright star where the handle meets the brush. The northern part of NGC 6960 is brighter than the southern part and reminds me of cigarette smoke as it leaves the cigarette. In the southern end, it widens and gradually fades out. 38x + OIII

NGC 6992 and NGC 6995 form the eastern portion of the Veil. This is huge and does not all fit into the 1 degree field of view of the 40mm TV Plossl (38x). it is very bright and I can see filaments, especially at the southern end. The eastern side is much brighter, while the western side is faintern and fades out. 38x + OIII

NGC 6826, the Blinking Planetary in Cygnus: Very small and bright. Obvious as an out-of-focus star. It's bright even unfiltered, but an OIII filter makes a big difference. This is visible with direct vision but averted vision makes it look twice as bright and twice as big. Blueish tinge without the filter. 101x + OIII

NGC 7008, planetary nebula in Cygnus: Small, bright pn located within irregularly-shaped dark nebula Le Gentil 3 - itself easily visible to the unaided eye. This is bright and triangular. There is a star at the apex of the triangle. It is brighter on the north eastern side. Only the brighter portions are immediately visible without a filter, but an OIII shows the whole object. 101x + OIII.

Le Gentil 3, dark nebula on border of Cepheus and Cygnus: large, irregular dark nebula. Visible to unaided eye. Also looked at through binoculars.

Sharpless 2-112, nebula in Cygnus: Easy to find. Faint. Small. Roundish. 101x + UHC.

NGC 1907, open cluster in Auriga. Auriga has some nice open clusters. NGC 1907 is one such, although a tad overlooked due to its close proximity to M38. Small, compressed and hazy looking at low powers. Increased magnification shows lots of foreground stars although the background stays nebulous. Rich. 101x.

After a cup of coffee and a general poke around the sky, I packed up at 0330. By then my feet were cold (and the cold was getting into the ankle joints, too; standing on concrete is not good because it's hard and cold) and it was getting more of a chore looking for stuff.

A good session and made up for the previous night's aggravations! Although I still didn't find the Perseus Galaxy Cluster...

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