Sunday, 29 November 2009

Art stolen from the sky

This is the current most wonderful piece of art I have stolen from the sky. It has a happy, pleasing quality about it. I can’t say why. Maybe it’s because it’s just pretty, or it’s because of the sheer otherworldliness of it. For instance, that bizarre Y in the middle. I enjoy the slight imbalance of the picture, it was intentionally cropped that way. The dark blobs on the right are made so much more interesting. Behind them is a little pocket of pink glow trying to shine around the edge. The two blue stars at the bottom are like incisors. They are top 2 of a little cluster of stars far out to the east of Orion. That cluster is the way to find the Rosette Nebula, which encircles them and is much bigger than I can fit on my pictures. I suppose I could pan around the area and get lots of images, but I haven’t come across a way of making seamless mosaics yet as in my opinion Canon’s Photo Stitch does a pretty clumsy job, especially for space art. I write this with appropriate ambient background music on: you could feel the sky, on geogaddi by the Boards of Canada. Definitely a case of the old adage ‘a picture paints a thousand words’ so I shall stop now!

The Pac-man Nebula

This is a significantly shaped cloud of glowing gas.


Here’s my latest picture of M33 on the society’s 20" scope; an improvement on the higher res. mosaic in terms of smoothness and aesthetic appeal. I just managed to squeeze it into the field of view using the Meade focal reducer lenses and tilting the camera. It’s quite surprising that this galaxy is the size of the moon. It is one of those vast celestial objects on the dark shores of the world visible to human eyes. Its visibility is strongly dependent on the sky transparency and the scattering level of light pollution. I’ve never seen it with my bare eyes, only the nearby cluster NGC 752, although it only takes the tiniest telescope to see M33. Big telescopes will reveal very subtle patches of brightness within its spiral arms. In other words, it really looks nothing like the photograph. To the lower left of centre is a HUGE nebula many, many times larger than our Galaxy’s Orion Nebula that has its own New General Catalogue entry.

Monday, 23 November 2009

Nuisance lighting

Industrial estates, some farms, large houses and gardens near the observatory seem to be pumping out wasteful amounts of light all night with only the cost of electricity to deter them. Where is the respect to nature and the environment? It’s high time to raise awareness of this issue, give encouragement to switch off or angle lights downward, or to start enforcing rules preventing light trespass and waste. With regard to security lighting… does the light really make the place more secure? At the observatory I prefer to leave the outside light sensor off to hinder would-be burglars being able to see what they’re doing. Studies (CfDS) already show that lights do little for crime prevention. The steady increase in lights filling in all the remaining dark spaces on the countryside map now includes lights that can leave a bright spot in your eyes from a distance of half a mile. To me these look at least 500 Watts per light. They include a certain “farm” on the Watton road and some ridiculously dazzling construction lights on the A11. Worst of all is Wymondham industrial estate – what a horrific waste. I am pleased that by pure luck the light on the industrial estate near me has just been removed. That one casted eerie enlarged shadows of passers by across my door! The picture above is of the school beside the observatory - who for some reason left their lights rudely shining across to the observatory’s al fresco telescope area.

Sun Dog

I rediscovered this picture of a parhelion or ‘Sun Dog’ on some beautiful wispy, icy clouds. It looks like it was taken some time in spring based on the position of the sun. This optical phenomenon is caused by flat hexagonal ice crystals refracting sunlight by 22º. The effect can also cause a halo at this distance from the sun, and even the moon. Light dramatically reflects off the ghostly swirls above it and the contrast in the background blues makes a lovely composition.

A just 2 minutes

Here’s a picture of M81, a galaxy similar in size to our own Milky Way, 12 million light years away in Ursa Major. It is also known as Bode’s Nebula as it was discovered before the idea of galaxies outside of our own. I got this wonderful final image with just four 30 second exposures at ISO1600 & f/3. It’s processed in a non-linear way with boosted contrast between the faint spiral arms and sky background, and also to show some detail in the dust lanes around the centre. In fact I have blackened the sky which was its usual muddy brown colour. Visually, through a telescope, it appears to me as a bright central nucleus surrounded by a hazy ellipse. The spiral arms are too faint to see so the full size is not visible. Very near by in the sky is M82, a galaxy showing lots of structure but I always find tracking down M81 a bit tricky.

Big scope peers into the depths of our spiral arms

Abell 20 is a faint planetary nebula in Canis Minor near Monoceros, which is nearly as wide from our perspective as the beautiful Ring nebula in Lyra. The main difference is that this one is about magnitude 14.7, nearly 6 magnitudes fainter and only 1/200 th as bright! It needs a hefty telescope like our 20” to help gather and capture its elusive photons, most of which are a delightful turquoise shade of doubly-ionised oxygen. The central star looks quite busy but only appears so from our distant vantage point. It is magnitude 16.5. Apologies for what looks like green rain falling diagonally across the picture. It is an artefact of some detrailing I did and the over-processing required to see the “faint fuzzy”.

Gassy young stars

This is me peering deeply into the Pleiades cluster. So deep, even with my field widener attachment, that I could only see two of the stars within the cluster. And this field is 40 arc minutes across. Now, obviously, this isn’t a properly deep picture, like you would see in some expensive CCD camera advert (that doesn’t give a price), or a magazine pic of the week. But to me it is deep, because it shows lots of blue clouds floating about between the stars, reflecting their spectrally blue cosmic light. It wasn’t a long, or particularly well tracked set of camera exposures, but it’s the subject I’m interested in, and my aim is to maximise the aesthetic appeal of the final picture. Contributing to that appeal is a particularly quirky set of flare lines coming off the star Alcyone at the left that provides a skewed detail to the picture. The streaky nebula at centre is named after the star, Merope which is only 30% as bright as Alcyone.

Messin' with filters

Lumicon’s 1 ¼" UHC filter is a superb addition to my visual astronomy toolkit. I’ve seen the stringy, fluorescent shockwaves of the supernova remnant in Cygnus, the North America nebula, and now I have faintly seen the glow behind the horse head nebula. But for photography it is a bit disappointing. The light is mostly rejected - it seems to be too narrowband for good imaging and the light really should be collimated first for it to block the correct wavelengths. I can’t quite work out why the photographic result should be so different to the visual experience at the eyepiece. Any comments welcome. I did 5 exposures that tested the tracking of the 20” scope (60-90 seconds each). Detrailing, stacking and processing resulted in this faint but fairly decent picture of the Horse head nebula's Hydrogen Beta (H-β, λ = 486.1342 nm) emission.