Monday, 21 December 2009

Winter clusters and nebulae, 20 December 2009

The first nearly cloudless evening for ages prompted me to carry out the big scope for an evening's chasing of winter nebulae. I set up the scope and left it to cool while it got dark and I gathered my stuff together. The weather has been very cold of late, with snow last Friday and subsequent days being below zero, with plenty of ice on the ground. Because of the ice, and not wanting to slip over, I didn't set up in my usual place on the patio, but further up the garden, on a concrete patch I often use as it does afford a better view of the sky (the patio is closer to the house and is more convenient for going in and out of the kitchen extension, which I use as a kind of 'observatory', with my eyepieces, charts and other stuff spread out over the work surfaces and the top of the freezer).

20th December 2009
Cold: -2
° C, stiff breeze, 78% humidity.
Some cloud on southern horizon and a waxing crescent Moon, 17% of full. NELM 6.0 TO 6.5 later. Some intermittent interference from neighbours' indoor lights (why do some people not have curtains?).
Seeing Ant II, transparency II-III

Instruments used: 12 inch f5 Dobsonian and 8x42 binoculars

After satisfying myself that the clouds were not about to spread out, they were hugging the southern horizon ('Don't even think about it, you sods!' I found myself saying out loud), I began with an attempt on IC59 and IC63 which are located close to Gamma Cassiopeiae. These are very faint nebulae and, after searching around the area with a medium power eyepiece and UHC filter I can't say in all honesty that I saw these. I saw a slight brightening in the area but that was it.The waxing 17% of full crescent Moon was a sod, surprisingly bright, and it seemed to take an age to set, if I hadn't known better I'd have sworn that the damned thing was stuck where it was!

Next was the planetary nebula IC 2003 in Perseus. This was easy to find, being located exactly halfway between Menkib (Xi Persei) and Atik (Zeta Persei) - put the Telrad finder between those two stars and you will find the nebula. It is stellar at low powers and needs an OIII filter to make it stand out and confirm the sighting. At high power it takes on a slightly fuzzy appearance. There is a slight bluish tinge to this (without the filter) and it has a definitely brighter middle to it. 101x + Lumicon UHC

IC 351 in Perseus. Slightly more difficult to find than IC 2003, it took me a search of around ten minutes to locate it, to the east of IC 2003. This is a tiny, very stellar-looking PN which is pretty bright. Definitely needs the OIII filter 'blinked' in front of the eyepiece to be certain of sighting. Does not look as fuzzy as IC 2003. 190x + Lumicon UHC

While waiting for Orion to clear the house roof (I wanted a crack at PK 198-6.1, located right next to Mu Orionis as well as to look at NGC 2024 and the other stuff in that area) I got the 8x42 binoculars out and looked at a couple of large open clusters in Taurus:

NGC 1647 in Taurus. Huge open cluster. Irregular, not quite round shape. Quite a lot of stars resolved, although hand-holding the binoculars meant it was almost impossible to count them properly. Impression of some brighter foreground stars and a lot of fainter backgrounds ones. I also looked at this with the scope but the overall impression with the scope was of a large, but not rich cluster. Nice. 8x42 binoculars

NGC 1746 in Taurus. This is even larger than N1647, almost twice its size. Contains brighter stars than N1647 but even less rich. 8x42 binoculars

NGC 1952 (M1) in Taurus. While in the area, I decided to take a look at M1, the famous Crab Nebula, as it is a number of years since I last looked at it. It can safely be said that this thing is not famous for being spectacular, as it is a rather nondescript elongated smudge of light. It is, however, famous for being the first item on Charles Messier's list of objects to avoid (for the purposes of not getting them confused with comets, which was what CM was really after) and for being observed by the Earl of Rosse at Birr Castle in Ireland, and it got the 'Crab' nickname from Lord Rosse, his sketch shows tendrils like a crab's appendages - but he had a much bigger scope than me! 190x

NGC 1907 in Auriga. Completely overshadowed by its neighbour, the vast open cluster M38, this open cluster is a nice small, rich cluster. Oval, with a number of brighter stars and a hazy background of much fainter ones. 190x.

PK198-6.1 (Abell 12) in Orion. Easy to find, being located right next to Mu Orionis, but easy to see? Not particularly due to the star's proximity. It is right in the glare from the star and it took high magnification, an OIII filter and a cover over my head to block out stray light for me to see something round, largish and faint next to the star, but I want to have another go at this when Orion is higher and the conditions are better. 190x + Lumicon OIII

NGC 2024 in Orion. Right next to Alnitak (Zeta Orionis, the eastern most belt star), this is slightly overwhelmed by the star's glare but is not hard to spot. The big dark rift  which cuts it in two is the most obvious feature with averted vision bringing out the faint nebulosity either side of it. A UHC filter works quite well on this, while OIII and H-beta kill it. The western half of the nebula, nearest the star, is brighter than the easten half. 60x + Lumicon UHC

By this time it was 2135 GMT (UT) and the clouds were moving in so I finished the session with the obligatory look at M42, the Great Orion Nebula and the detached portion M43. This, in the 40mm Plossl (38x) with the UHC filter attached, was spectacular with tendrils and nebulosity everywhere. The dark indent next to the Trapezium was very obvious as were other dark areas, giving the brightest portion of it a mottled appearance. 38x + UHC 

Packed up as the clouds began to fill the sky.

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