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Observing report, January 12, 2013

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#1 Eric A Jensen

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Posted 14 January 2013 - 12:13 PM

This is the second dark-sky trip with the 22" Starmaster this weekend. Conditions were very much the same, both with respect to transparency, seeing and temperature (i.e. cold!). We started at 20.20.

I had selected some galaxies in Draco to start with, most of which I had not yet logged:

NGC 3252 was not large at 250x magnification. It was a very elongated glow with a smooth brightness profile and a core suggested at center. Low surface brightness.

NGC 3183, close to 3252, was noticeably brighter and seemed uneven at 120x and 250x. Foreground stars were seen. It was also elongated, but thicker. Some central concentration, but without an obvious core.

NGC 3147 was just under a degree south of 3183, and was considerably brighter. Roundish in shape with a bright core and a halo diminishing diffusely towards the edge. At 250x it was imposing and bright in the field, with weak irregularities in the halo suggesting it may have been a spiral.

NGC 3144 and 3155 were a bit north of the previous one. 3144 was right by a star that interfered. 3155 had an apparently lower surface brightness and perhaps a larger extent. None of them were very bright or contrasty at 120x. At 250x, NGC 3144 was still small and faint. NGC 3155 at this magnification was visibly larger than the other one, with some central concentration. Grew somewhat with averted vision; roundish.

Now to the east, NGC 3343 was very small, but had a small, bright core giving it high surface brightness. Round / weakly elongated. 250x.

NGC 4589 was brighter and larger than the previous ones. Had a round shape and bright core. 250x. Just north-west of it was NGC 4572, in the same field at this mag. It was much fainter, elongated and with much lower surface brightness. Seen with some averted. The pair was a good example of galaxies having very different appearances.

NGC 4648 was 1/4 degree east-north-east of 4589. It had a bright core, but a smaller extent.

We now moved to other objects and regions.

IC 361, open cluster in Camelopardalis: At 120x, this was a faint or very faint cluster, rich in dim resolved stars against a grainy unresolved background. Quite small in extent, 188x helped resolution. Had no central concentration, was well detatched from the background.

PK 147+4.1, planetary nebula in Camelopardalis: Close to the previous IC cluster. At 120x the planetary was close to stellar. At 250x and 375x, it was obviously a disk – the latter magnification being most suitable. It was a small round disk, not bright, but visible with good contrast using an OIII-filter. Was uneven, possibly annular.
The Rosette Nebula in Monoceros: This emission nebula was huge and structured at 85x with an OIII-filter! Extended well-beyond the field edge, so we moved the scope around to catch it all. Surface brightness was fairly low, but contrast was good due to the filter and sufficiently dark skies. The north-western region was obviously the brightest, and here showed several elongated dark patches that likely were dark nebulae. In all, an uneven, mottled nebulous system.

The Great Orion Nebula: As opposed to the evening before, an OIII-filter was now used at 85x. The brighter core regions were greener and perhaps not so visually pleasing; on the other hand the extended whole of the nebula was seen with unbelievable contrast. The entire nebula was just contained within the field edge of the 31mm Nagler. There were many structures and plenty of unevenness in these outer parts. Just within the south-south-western edge, there was in fact a large dark region, reinforcing the impression of a bubble-shape. I often prefer M42 unfiltered, but do realize that a filter has its advantages – It depends on what aspect of this object one wishes to emphasize.

M1, The Crab Nebula, supernova remnant in Taurus: At 188x, it was very large and seen with good contrast. It is in fact an impressive object. It had an uneven, oval appearance and had diffusely brighter/darker areas. It was structured in an ill-defined manner.

NGC 1618, 1622 and 1625, galaxy trio in Eridanus: These were situated along an arc just north of a bright star. The galaxies were of similar brightness, but were not seen with very good contrast due to their somewhat low elevation. But they were bright. All were elongated, 1618 more elongated than 1622 and had a certain central brightening. NGC 1622 was smaller, with a somewhat brighter core. NGC 1625 was the most elongated, probably also the largest, and did not have such an obvious core. 188x, 250x.

NGC 1587, 1588 and 1589, galaxy trio in Taurus: Another triplet, in the same region of the sky, but now over to Taurus. NGC 1587 and -88 were right by each other and formed a tight pair at 250x. Both were round and compact, but 1587 was considerably larger than 1588. It was also the brightest. Both had central concentration up to a core. NGC 1589, north of the other two, was more elongated and also had a core. Surface brightness seemed similar. It was probably the brightest. All three just fit into the field at this magnification. All were seen with fair contrast.

NGC 2261, Hubble's Variable Nebula, reflection nebula in Monoceros: This was seen very well indeed at 250x. It had a conspicuous, sharply defined comet- or fan-shape, with a star located right at the tip of the "head". The nebula extended outwards and widened, and had a darker area towards one side, within its extent. With averted vision, it grew somewhat, revealing a fainter nebulous region continuing in the direction away from the star. A strange, unique object with high surface brightness.

NGC 2022, planetary nebula in Orion: This lies east of the head of Orion. It was a nice, grey disk standing out well from the background unfiltered. Of moderate size. The disk was uneven, having an apparently superimposed ring of rather low contrast within the circular edge of the disk. 188x, 250x?

NGC 4102, galaxy in Ursa Major: A bright galaxy with a considerable halo in averted vision. Well-concentrated towards the middle. Close to the center was a darker region, which may have been a dust lane or possibly the space between arms. The core itself was small and slightly elongated. 250x.

NGC 4605, galaxy in Ursa Major: A highlight among the NGCs we saw! A bright, very elongated edge-on. It was asymmetrically thicker and brighter. It was uneven, and with time these structures definitely looked like dust lanes located in various areas. Reminded of M108. 250x.

NGC 2403, galaxy in Camelopardalis: The most impressive object in this constellation. A large galaxy filling much of the field at 188x. The core was broad and had moderately high surface brightness. The elliptical halo was very uneven, with a lot of structure. Elongated darker and brighter areas comprised the spiral, which was easier to recognize using time at the eyepiece. Several bright patches – emission nebulae – were seen. One of these was outside of the galaxy's visible extent.

NCG 2903, galaxy in Leo: We had seen this on the previous evening. At 250x, it was large, detailed and impressive. See the description in the previous report.

We packed up after 23.30. A very nice evening!

Eric

#2 IVM

IVM

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Posted 14 January 2013 - 01:26 PM

Nice report! NGC 2403 is one of my favorite galaxies. I wanted to reobserve it just this week when I was doing and re-doing Camelopardalis with my 16". But the sky closed with a bang - likely till February - just before I could get to that area of the constellation. One compact patch in this galaxy has its own NGC number (2404). About a year ago I made a sketch of it with my 12" SCT:

http://ivm-deep-sky....1/ngc-2403.html

Coincidentally NGC 2404 was discovered by Bigourdan with a 12" refractor. The most prominent spiral arm segment was described already by William Herschel as a "branch". My observation with the 12" showed also the area of the Hodge star associations 35 and 41 as a distinct but confused patch. Previously I had seen the galaxy with a 4" but recorded no detail. It is thought to belong to the M81 group.

#3 galaxyman

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Posted 14 January 2013 - 02:54 PM

Hey Eric

Very nice report with some very nice DSO's, including the trio in Taurus that I discuss in this month's Galaxy Log video.

Ngc 4605 is a really nice galaxy that reminds me of a smaller version of Ngc 4631 (the whale).


Karl
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