Friday, 9 April 2010

Observing, April 8th 2010

The first clear night in April so far that I was able to observe. While I am a deep sky observer, I do like to look at the planets now and then and it would be a shame to ignore Mercury when it is favourably placed as it is at present. Both Venus and Mercury are low in the western sky just after sunset and, through my birdwatching spotting scope, I saw Mercury as a disk. I also took a couple of - bad - photos with my Canon 40D and 400mm lens, one of which is this one. I labeled it as Mercury doesn't show up that well (click for larger picture):

By the time I'd finished messing around with planets and finished setting up the scope and gathering all the observing bits and pieces together it was time to observe. Unfortunately it wasn't as clear as it promised, with a very thin haze which scattered light around, making the naked eye limiting magnitude a very poor 5.8 to 6.0.

Clear, but with a very high thin haze.
Cool: +6C, down to +2C later.
Very slight breeze now and then
Seeing: Ant II; Transparency: III
NELM: 5.8 to 6.0 due to light scatter caused by haze - poor for here.
Instrument: 12 inch f5 Dob, 22mm Televue Panoptic (69x), 15mm Televue Plossl (101x), 11mm Televue Plossl (138x), conditions not good enough for higher magnifications.

I spent most of the session in and around Ursa Major which is rich in galaxies but no so rich that you're overwhelmed by sheer numbers of the things, which is the case once you get into Virgo and Coma B. All these observations are of galaxies.

NGC 3613 UMa: roundish, fainter than 3619 (which is in same f.o.v at 69x) with a much fainter core. Well defined against the sky.

NGC 3619 UMa: Bright, oval, small. Well defined. Bright core.

NGC 3610 UMa: Small, bright and round. Bright core.

NGC 3556 (M108) UMa: Yep, a Messier, but this has shown up on the H400 list, so here it is - Large, almost edge-on. Can see dust lane. Star superimposed on top of galaxy; it looks like a stellar core, but isn't.

NGC 3982 UMa: Not quite round. Bright. Bright core surrounded by halo.

NGC 3972 UMa. In same field of view as 3982, but much fainter. Elongated. brightens somewhat towards centre.

NGC 3998 UMa: Much larger than previous two galaxies. Round with some brightening towards centre.

NGC 3992 (M109) UMa: Large, oval and featureless. Uniformly bright with three foreground stars superimposed on it. Quite boring, really.

NGC 3953 UMa: This one is very nice. It is large, elongated north-south and is bright. It also has a large nucleus which is brighter than the surrounding galaxy.

NGC 4026 UMa: Bright, elongated NE-SW. Lovely edge-on spiral with a very bright nuclear bulge.

NGC 3729 and NGC 3718 UMa: These make a nice pair. Both are oval and pretty faint, although easy to find. Both are uniformly bright with no hint of a nucleus. 3729 is the larger one of the two galaxies. Hickson 56 is nearby but the crap hazy conditions made this invisible.

NGC 3631 UMa: Round with bright compact core. Pretty large and pretty bright. Bit of a bugger to find though, due to its location out on its own, just below the Dipper bowl. Hint of spiral structure with averted vision.

NGC 4565 Com: A perennial favourite! This is an edge-on spiral and is spectacular to look at. At 138x it stretches right across the field of view. Very bright with very bright nuclear bulge and a very prominent dust lane which cuts it in two.

NGC 4494 Com: Near 4565 this is another bright galaxy. Round with bright core.

NGC 4448 Com: Located just off the apex of Mel 111 (the Coma Berenices Star Cluster) this is a bright not-quite-edge-on galaxy. Nice bright compact core. Elongated east-west.

NGC 4559 Com: Large spindle-shaped even glow. Well defined against background sky.

NGC 4278 Com: In same f.o.v at 69x as NGC 4283. One is elongated and brightens towards its centre and the other is smaller, brighter, rounder and has a more compact core.

NGC 4274 Com: Bright oval. Almost edge on. Brighter middle.

By this time it was getting late, thanks to that thief of observing time BST. As I had to be up at 6am for work, it was time to pack up and head in.

At the Isle of Wight Star Party back last month, Owen Brazell was selling off a few spare eyepieces, which he'd replaced with Televue Ethoses and I bought a very nice 22mm Panoptic from him, which has now become my main 'searching' eyepiece. The barrel is scratched but the e.p. is in otherwise excellent condition and it has replaced the 20mm and 25mm Televue Plossls in my collection - now I have two redundant eyepieces!

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