Category: Deep Sky

M17 – The Swan Nebula

I’m slowly working my way through the pictures I took in Yorkshire. This one is of an object I spotted as a bright hazy patch while scanning the Milky Way through binoculars. A long exposure photo confirmed it as the Swan / Omega nebula. To my eyes it looks more like a swan than the uppercase Greek letter omega (?).

M17 is an object very similar to the Orion Nebula – an active star forming region. The cluster of young stars within it have yet to reveal themselves visually as they are largely obscured by dust within the nebula. They can however be studied in infra-red where the dust absorbtion is much less. The bright bar of the nebula is about 20 light years long and the nebula is located in the Sagittarius arm of our Galaxy, 5900 light years away.

This image is comprised of 7 three minute exposures through the ZenithStar 70 at ISO1600 with an unmodified Canon 350D.

Deep Sky Galaxy

The Milky Way

The Yorkshire sky had a much better southern horizon than I get at home so one of the things I wanted to image was the Milky Way. Unfortunately, I was plagued with cloud in this direction so all I managed was 2 3 minute exposures at ISO 800 with the 18-55 Canon lens. Even these frames had some cloud reflecting the sodium lighting of the towns to the south but the results show promise with a dark sky down to the horizon.

Notice that the Coathanger stands out well in this picture, almost dead centre.

Deep Sky Nebula

Dark Nebulae

Dark nebulae are clouds of cold gas and dust which only reveal themselves by blocking out the light of more distant stars. Consequently, most of them are to be found in the plane of the Milky Way where stars are most densely packed. The astronomer Edward Barnard catalogued many of them from photographic plates and they are now known by their ‘B’ number.

This image shows B142 & B143, just to the west of ? Aquilae or Tarazed.

As I wasn’t too sure of the exact position of the nebulae I positioned Tarazed at the left hand side of the field and took 11 3 minute exposures which were then combined for the final image. Telescope was the ZS70.

Deep Sky

North Yorkshire Skies

I’ve just got back from a week’s holiday in the North Yorkshire Moors. We were staying at a cottage at Low Garth in Fryup Dale. 3 nights were clear up until about midnight on each night and I took a fair few photographs and as I process them I’ll post them here.

The night sky quality in the Moors is very good as there are no major towns nearby and Teeside was conveniently hidden by the side of the valley we were located in. The only time you were really aware of it was passing clouds reflecting an orange glow.

Equipment was the Astrotrac with Canon 350D and either the ZenithStar 70 or Canon kit 18-55 zoom. I did have a repeat of the issues with the Manfrotto 410 head working loose, I think it’s the other axis this time, so it’ll be back for repair and I need to think about an alternative. While expensive, the Astrotrac TW3100 wedge looks very nice!

While I’m processing some of the images here’s some fun I had with an asterism between Sagitta and Cygnus. CR399, otherwise known as ‘The Coathanger’ is an easy binocular object in Vulpecula. 5x 30 second exposures at ISO 1600 through the ZenithStar 70mm refractor. As usual, click on the image for a larger view.

Deep Sky Nebula

The Little Gem

More formally known as NGC 6818, this planetary nebula in Sagittarius was dicovered in 1787 by William Herschel. Despite it’s relatively low visual magnitude of 9.3, because it is such a small object it can be photographed with quite short exposures and this image is a stack of 52 5 second frames on the club 20″. I used a Canon 350D at ISO800.

It has two distinct components; a spherical outer shell and a brighter core. Size is a diminutive 25″.

Deep Sky Open Cluster

Messier 103

Discovered by Mechain on the 27th March 1781, M103 became the last entry in Messier’s original catalog. Interstellar extinction of about 1.5 magnitudes makes determining the precise distance difficult but it probably lies about 7200 light years away. The cluster diameter is 17 light years and the bright star in the field is Delta Cassiopeia.

This was the first time that I’d tried out a new piece of software, DSLR_Logger from the AstroTrac Yahoo group. It’s main purpose is for determining precise polar alignment of the mount. I will write more about this program when I’ve had a chance to explore it rather more fully.

This was also the first outing for my new Williams Optics Field Flattener 3 on the 70mm.

Deep Sky Open Cluster

M45 – The Pleiades

Searching through some old folders on my PC I came across 5 images of the Pleiades that I hadn’t previously processed. Taken on the Astrotrac with a 75-300mm Canon zoom lens set at 200mm, each is 3 minutes long for a total of 15 minutes exposure.

The resulting stack had masses of red sky noise but removing this and applying a non-linear stretch starts to show the dust cloud around the brightest stars of the cluster.

Deep Sky Nebula

Sagittarius

From the northerly latitudes of the UK, Sagittarius is low down on the Southern horizon during the summer months. Looking towards the centre of our galaxy this region hosts some of the most stunning star fields of the night sky and is also home to some bright nebulae. Two of these are captured in this wide field image; M8, the Lagoon nebula and M20, the Triffid nebula. Also in the frame is the open cluster M21.

Whilst these objects appear close together in the sky, M20 is a foreground object with M8 considerably further away along with M21. The apparent size of the long axis of M8 is about 1.5 moon widths and the object is rather larger than the Orion nebula (60 x 40 light years).

Being a bright naked eye object (under a dark sky) means that reasonable results can be obtained from relatively short exposures. This image consists of 18 minutes of luminance frames and 9 minutes each of red, green and blue.

Observatory: Moorock, Australia

Telescope: Takahashi STL-11000M

Camera: SBIG STL-11000M

Deep Sky Globular Cluster

Messier 10

Post author By admin
Post date June 5, 2010
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We got back from the evening at Kielder at about 1 in the morning and as it was clear, albeit, not very dark I setup to take some pictures of M10 in Ophiuchus. By 2:30 it was already getting light and the dawn chorus was getting going but I got 15 3 minute exposures at ISO 800 for this image. Telescope is the ZenithStar 70mm F/6.

Deep Sky Nebula

Diffuse nebulae in Cygnus

Post author By admin
Post date May 31, 2010
No Comments on Diffuse nebulae in Cygnus

At the beginning of the holiday in Northumberland we had an evening where the cloud passed through just as the moon was setting. Having a restricted southern horizon I looked instead to the East where Cygnus was rising and decided to image the region around the bright star Sadr. Some puzzling over the hit or miss drifting I’d been getting with the AstroTrac lead me to the conclusion that I needed the polar scope on the left side of the mount to get good results. This has subsequently been confirmed by some recent posts on the Yahoo group and the problem is due to the scopes being manufactured with the tubes slightly misaligned. There is a mod available to correct this that involves fitting a collar with three grub screws around the tube. This will be worth a closer look.

Polar alignment was pretty close on this occasion so I took 16x 3 minute exposures with the ZS70 and unmodified Canon 350D and stacked the results.

The bright star to the left of centre is Sadr. There is an open cluster (NGC 6910) to the left of Sadr. The remainder of the image consists of HII emission nebulae that are catalogued in the DWB index. One Barnard catalogue object (B344) is visible just to the right of the bright orange star top centre of the image.