Monday, 31 March 2008

Observing platform and second light

I built myself a little 'observing platform' in the garden, from old concrete blocks, yesterday. I dug a large square hole and laid the blocks in it, getting them as level as possible to provide a nice, stable platform for my Dob and it works well, getting its first use that evening.

The Dob got it's second light (as it were) yesterday evening. I had the best views I have ever had of the Owl Nebula (M97) in Ursa Major; it had a definite greenish tinge to it and, for the first time, I saw the 'eyes' - two dark holes in the nebula - that give this interesting PN its nickname, although these were only really evident when I put an OIII filter into the eyepiece.
It wasn't a deep sky night, due to the high cloud - there seemed to be a 'cover' of very high thin cloud - but the views were not too bad of the brightest objects although the scope needs collimating, as while low magnifications are ok, the view through higher mags is out of focus, with a kind of shift to one side (i.e. one side of a star or planet is good, the other awful). This is due purely to collimation issues, so once I have sorted that out, the views will improve. I have bought a laser collimator for this purpose. Collimation isn't hard, just a bit of a pain in the arse to have to do.

Increasingly bad conditions and the need to have to get up early for work meant I had to pack up at around 9.30 pm. Nearly as irritating (although not a reason for packing up in itself) was a light aircraft that kept flying round in circles - funnily enough, and I have lived under Heathrow's flight path in the past, I never find the noise of big jets anywhere near as annoying as the buzzing drone of a light propeller aircraft.


If I were ever to come to power, one of the first things that would go (along with unneccessary lighting, animal experiments and child benefit) would be that infernal invention 'British Summer Time'. Putting aside all the ill-informed rubbish from some members of the public about 'extra daylight' (there isn't, you idiots) the fact that, due to this irritating tinkering, it gets dark an hour later is a major pain in the backside from an observing point of view, particularly when I have to be at work at the unreasonable time of 0800 the following morning.

Sunday, 23 March 2008

First light of 12-inch

The evening started off clear so I set the 12-inch up on the patio. After letting it cool down for a while, I aimed it at some bright stars in a rapidly-worsening sky (isn't that just typical??) and M81/M82. The collimation could do with a bit of slight adjusting but the view, despite the crap sky, was pretty good and I tried out a selection of eyepieces on it. Sadly, I had to pack up after only half an hour because the sky was becoming increasingly opaque. Annoying, but hopefully we'll get some nice clear nights soon, once Spring gets well underway, and I can test it properly. Anyway, I'm pleased with what I have seen so far.

I have sent off for a laser collimator from Telescope House, a cheapish one at £34.99, so hopefully that will make collimating the scope easier and quicker. This is the first large Dob I've owned so keeping the mirrors aligned properly will be more of an issue.

New 12" Dob

I went and collected the 12-inch Dob this afternoon and it's just as well I didn't get a 14" or larger or a longer f-ratio mirror or it never would have fit into my car, and I wouldn't have been able to carry it - the 12" is quite heavy, but I can (fortunately) lift it comfortably. On getting it home, my aunt started fussing slightly over the size of the thing: 'Big enough, innit?' and 'Where are you going to put that?' (I don't think she quite grasped the size of a 12" Dob until she actually saw it!).

Here are a few photos:

It fits neatly into the corner of my room:

Looking down the tube:

It was made with a 2-inch focusser but this can be adapted for 1 1/4-inch eyepieces, such as all mine are until I replace one or two with 2-inch versions (2-inch is the upper picture, 1 1/4-inch is the lower pic):

I am hoping for a clear night tonight so I can see how well (or not!) it works. Richard said that it focusses, but a bit further along the focus (it racks almost right in) than he'd like, so if that is a problem with some eyepieces, the mirror would need to be raised.

Tuesday, 18 March 2008

It's finished!

My 12-inch Dob is now finished and I should be able to collect it at the weekend. I now hoping the weather will co-operate and I do not get a case of the 'new equipment = cloudy weather for weeks' curse.

Saturday, 8 March 2008

IW Star Party Part 1

Friday: I finished work earlier than I thought so I headed off to the merry gathering at Brighstone Holiday Camp. When I got there it was less peopled than the Marie Celeste due to the fact they were all at the observatory at Winford (just down the road from home). Anyway I had a wander round and looked at the dangerously close cliff edge and the chalets that had been abandoned due to severe erosion. The whole Island is prone to erosion but the south-west side is worst affected of all. Basically it is greensand sandstone that sits on top of Gault clay. The rain percolates through the sandstone but as the clay is not porous the whole lot is prone to slippage, with disastrous results - many places that were once miles inland are now teetering on the edge.

Huts teetering on the edge.

View of the camp site, looking north

View looking east-south-east, back towards Chale.

VAS member Bill Johnston's Celestron C14

As it looked like it was going to be clear, I drove home, picked up my stuff and drove back; Radio Solent's weather forecast was excellent, promising clear skies and a frost. When I got back to Brighstone, Owen Brazell was setting up his gorgeous Obsession 20" Dobsonian and others were getting their gear ready as well. Dusk was falling and it was looking reasonably good.

Unfortunately this state of affairs did not last long. A threatening bank of cloud in the north-west decided to make its presence felt and soon blanketed the sky. Soon all observing was being done through sucker holes that kept opening and closing aound Orion, Canis Major and Monoceros. I managed to get a look at NGC 2359, known as 'Thor's Helmet' in Canis Major, through Owen's Obsession. This is a comparatively bright nebula and, visually, looks more like a referee's whistle more than a Viking helmet.
Of course, the scopes were more engaged looking at the lollipops, because the conditions were no good for serious deep sky observing and, naturally, Orion's famous M42, the Great Nebula, was a main feature. This showed superb detail though a Meade 10" and even more so through the 20" with a UHC filter attached, with filaments and extended nebulosity. You could easily see the structure that 18th and 19th century observers such as the Herschels and Lord Rosse drew and described, with the hatched structure very evident. I'd never seen this structure visually and had always thought the old drawings a little fanciful - but not any more!

Soon the sky was a complete cloud out and, as I'd had to be up that morning at stupid-o'clock to go to work, I packed up and drove home at 9pm.

It was a good fun evening and, despite the limited observing, was full of conversation and happy faces. I hope our little Isle of Wight Star Party grows and grows. It has a bright future, despite the iffy weather.

More to follow...