Monday, 26 December 2011

More delights of Orion

The chocolate box of Orion contains a selection of objects from visible to photographic beauties. The area around Alnitak (ζ Orionis) is particularly striking with a good telephoto lens. This particular lens has produced a couple of new nebulae via internal starlight reflections. The spike at top left is Alnilam trying to peek into the edge of the shot. I piggybacked my modified 1000D camera on the club's 9 1/4" scope on a CG5 mount and without guiding, got some 2 minute exposures through an old f/6.3 400mm lens. The RA drive had a wobble with a 10 minute period, causing most of the pics to be slightly trailed, but I managed to stack 12 of them with a combining method that minimised trails. So, here I present 24 minutes of exposure centred on the dark cloud called the Horsehead nebula B33, which protrudes against the hydrogen-red background of IC 434. The blue reflection nebulae NGC 2023 and IC435 can be seen below the horse, shining from within the sooty cloud. The more yellow or pinkish Flame nebula, NGC 2024, appears attached to the other side of Alnitak, and this can be seen, albeit dimly, in telescopes much more easily than IC 434. The grapefruit like colour tells us that it is not exclusively shining in hydrogen red light and there must be some cosmic dust scattering component to its colour, rendering it visible to human night vision.

Thursday, 22 December 2011

The Perseus Cloud

A dim patch of light emerges from the dark cloud in southern Perseus. This is NGC 1333. I thought I'd have a second try at this object with my modified camera on the 20". I had a good dark night when the object was quite high and plenty of light gathering power. It was a bit of a struggle getting good auto-guiding, as it is a dark cloud and there are not many bright stars nearby to guide on. I did a bit of masking and selectively blurring the dim nebulosity, in order to try to smooth out the background, but started to get into 8-bit processing artefacts. In the final image (33 x 30second & darks, flats, etc.), reddened stars abound in the dark cloud, and the blue reflection nebulosity fades into the darkness around the edges. A few dark lanes cross the nebula and a few spots of activity show up dotted off to one edge. The large dark cloud crosses the centre of the image and background stars appear to peek out to the right edge. The width of this picture is similar to that of the moon.

Wednesday, 21 December 2011

Breckland Skies in Winter

I love the return of these beautiful constellations on freezing cold nights. It was dropping well below freezing and as I looked south out of the dome at Breckland Astronomical Society I could see stars right down to the horizon. There was one star especially low down below the constellation Lepus, which I recognised as Pheat, from Columba the Dove. I couldn't see the other two stars near it - but I grabbed the Canon and gorilla pod and clamped it onto the edge of the dome, pointing south. I found I could fit in all of Canis Major and Orion with the standard lens set to wide. I processed to reduce a bit of the background glow, but it was much stronger towards the horizon. An odd cloud was floating through Columba, which I could see. It wasn't moving fast, and appeared pretty small, but it managed to smear out on this image. There were a few high clouds drifting by which I could only see on the photographs. The camera managed 21 good 15 second shots before the battery ran out of juice in the cold and I stacked them in Deep Sky Stacker. Hence the motion blur across the southern horizon. If you look closely you can see the red R Leporis off the upper right of the main pattern of Lepus, next to a whiter star for comparison. I have not processed to show the Rosette, Horsehead, Flame and Orion nebula.

Saturday, 3 December 2011

NGC 40

Here's a pretty little stellar remnant that's visible in average telescopes most of the year from the UK. NGC 40, which can be found in Northern Cepheus, shows up very red on film, but is blue in appearance even in large telescopes. Due to this bright redness it shows up very quickly on camera. I got a handful of pictures of 30 second duration, some 10 second and some 3 second, stacked them, then averaged and sharpened them. I think it looks quite a flowery little nebula.

Thursday, 1 December 2011

The Intergalactic Wanderer

The intergalactic wanderer (NGC 2419) is actually not wandering. It is in a 3 billion year orbit around the Milky Way, which takes it further away than the Magellanic Clouds. It's currently 275 000 ly from us and 300 000 ly from the milky way's centre. I remember reading some notes in"Cirque du Ciel" (actually Cartes du Ciel) that the individual stars are 17th magnitude. Some facts about it don't square with me. I read that this globular is huge, and compares to omega centari (see recent posts), which has millions of stars. It is intrinsically very bright in total and appears as a 9th magnitude fuzz in the scope. But the individual stars must be 17 or so magnitudes below that (because 17 magnitudes = a factor of 6.3 million in brightness), more like 26th mag. Perhaps there is a huge range of brightnesses and the brightest ones around 17th magnitude. It is a big, big thing a long, long way away in any case! I wonder if it can sense the dark matter halo? The cluster lies in the direction of Lynx, near the twin stars Castor and Pollux from our humble perspective. I did a colour blur on this image and upped the saturation, sharpened a bit to make it all pretty. I suspect the colour went a little bit crazy along the way, but I love those colourful, spiky starbursts.

Spooky, Nebulous Fingers.

WE pointed the twenty inch at the Eastern Sky, so we could get a nice long exposure without rotation. Rising nice and high is the constellation Auriga, the charioteer, and in its centre lie some interesting patches of nebulosity. The "spooky, nebulous fingers" in this photo are otherwise known as the central part of IC405. There's a nice bright guide star here for us. I got 30 minutes worth of luminance, colour and dark images, using the Atik at -20 C, binning 3x3. I stacked in MaximDL then processed by blurring the colour frames, aligning and colour combining. An auto flat overdid things, so I averaged the autoflat corrected frame with a copy of the uncorrected frame. Next, I ran Digital Development and liked the contrasty effect, so I did the same thing with this. I couldn't mamange to get bright colours, they just don't seem to be there in this object. I think nebula filters Ha OIII Hb are the way to go! I did a small manual detrail using 'layers' and 'darken' on it to get round stars. This object is also somewhere in my past blog. Hopefully this pic is an improvement.