Essex CO6 3AQ Tel: (01206) 242596
glide@esgc.flyer.co.uk
"essexandsuffolkglidingclub" |
Wormingford Airfield, Fordham Road, Wormingford, Colchester, Essex CO6 3AQ Tel: (01206) 242596 glide@esgc.flyer.co.uk "essexandsuffolkglidingclub" |
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This is a timeline of me figuring out how to use my new toy. I have quickly found out that this kind of thing isn't easy, and I am making all the major mistakes in the book and discovering some new ones. So hopefully as I get better at it, so will the pictures...
The massive instrument itself, set up in my living room. It's a 10" Meade LX90.
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18th December 2008:
The first effort, using a focal length reducing lens, a few stars in the Pleiades cluster, showing horrible problems at the edges. The stars should be points but look like comets.
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26th December 2008:
Similar problems with the Pinwheel galaxy. This is called coma and it should not be happening. But I'm fairly amazed that I got the galaxy to show up at all.
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2nd January 2009:
Similar problems with the moon, same lens, causing the bloom around the moon and general fuzziness away from the centre.
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6th January 2009:
Without the seemingly dodgy lens, a much narrower field of view, coma problems gone, and not a bad image of Copernicus crater on the moon. It's about the size of Essex.
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24th January 2009:
Trying again with a replacement focal reducer, coma problems back again in this image of Rigel, the brightest star in Orion (the blueish one at the bottom right), so maybe this problem is not going away.
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Same date, M42, the Great Orion Nebula, with the dodgy lens, same problem.
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Same date, M42 again, without the dodgy lens, but with a less powerful focal reducer and therefore a narrower field of view... now I seem to be getting somewhere, no coma, but I messed up the contrast on this one and the stars are bloated... and the sky was very hazy indeed, and not much good at all for this. It can only get better, and one day I will add in some colour.
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27th January 2009:
M42 yet again, with the dodgy lens which I now realise is actually OK, but the real problem was that the stupid instruction leaflet did not account for the colour filter slide on my camera, so it was all 17mm too far back. This shot was dashed off as a test, so I hope I can do better than this in due course, but one problem is solved anyway. The contrast is better but I am not sure why the stars are a bit pear shaped. I think they may be bloated partially due to out of focus infra-red, which I can filter out in future.
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14th February 2009:
M42 yet again, with an infra red filter. Lots of moisture in the atmosphere and some dew on the corrector plate this time, and in fact clouds totally ruined most of the frames, so this is a stack of only 14x 4-second exposures. An improvement nevertheless, now resolving the central stars better, but I am still finding the software extremely unfriendly, e.g. it occasionally does something irreversible to 200 image files at once, and that's half an hour wasted... but at least slowly getting better, and the stars are not pear-shaped any more. And I do detect dust doughnuts - aargh! I must have messed up the flat field division somehow - see below.
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Not only dew and clouds, not helped by satellites getting in the way tonight...
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The dust in the optics... here's the "master flat frame" for the session, showing five dust doughnuts (diffraction rings) caused by specks on the CCD chip itself (which is actually very clean), and lots more dust elsewhere in the optics (on the IR filter and focal reducer lens) making those bigger rings. This includes the offending doughnuts in the M42 image above.
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So I have tried again from the original data - this looks a bit better.
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15th February 2009:
Or how about this one? I have just found out that I can click the "Log" button more than once to really bring out the nebula.
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