Distant giant: The Pinwheel galaxy

pinwheel-galaxy-messier-101The short nights of spring reveal a view unobstructed by the Milky Way, with slim pickings for wide-angle astrophotography. But there are some distant giants to be seen. The Pinwheel galaxy is one of them.

The massive galaxy stretches 180,000 light-years edge to edge. Despite this vast size, the face-on nature of the galaxy, and the huge distance, make it a appear quite dim. The combined light of a trillion suns barely registering on the 30 second exposures. The combined time of 30 minutes in the stacked image above reveals more…

The spiral structure of the galaxy, and the many bright nebulous regions within can be seen. Also revealed are dozens of the smaller galaxies residing in the area. Alhough these can be tricky to distinguish from the bloated stars, a problem made worse by the stacking process.

The full image below shows how tiny the Pinwheel galaxy appears in the frame of the 180mm lens. Not quite up to Hubble deep field standards, but not bad for a regular camera and home-made tracker!

Messier 101 the Pinwheel GalaxyImage details: Nikon D7000Nikkor 180mm f2.8 at f2.8. 30 minutes (60 x 30 seconds) at iso 800 using didymium filter. Stacked with Deep Sky Stacker and tracked with barn door tracker.

Comet Lovejoy, Owl Cluster & Dolphin Nebula

Comet Lovejoy and the Owl ClusterComet Lovejoy continues to shine as it journeys through the Solar System. Early last week the comet passed the Owl Cluster in Cassiopeia, making for another great photo opportunity.

With one of Cassiopeia’s brightest stars ‘Ruchbah‘ (right of shot) guiding the way, comet Lovejoy is an easy target to find at the moment. It’s surprising to see how bright the tail still is, with plenty of structure still visible. (Click the image for a larger version).

Just below Lovejoy sits the brilliantly named Owl Cluster, with the two brightest stars forming the eyes. The small nebula just above the comet is the little known Dolphin nebula, a small planetary nebula around 850 light years distance. The cluster of stars at the top right of the image is Messier 103.

Image details: Nikon D7000Nikkor 180mm f2.8 at f2.8. 16 minutes (32 x 30 seconds) at iso 800 using didymium filter, plus 2 minutes (4 x 30 seconds) at iso 800 using . Stacked with Deep Sky Stacker and tracked with barn door tracker.

Aurora through the mist

Last night a solar storm hit Earth producing one of the strongest auroras of this solar cycle. Unfortunately for me, a misty evening drowned out much of the show. All but for 20 minutes when the silent display flared up strongly enough for me to catch a glimpse… Continue reading Aurora through the mist

Flaming Star nebula

flaming star nebulaAfter giving up on it a couple of weeks ago, I decided to have another try at the Flaming Star nebula, this time under better conditions…

Heading a few miles out of town to darker skies makes a huge difference for such a faint subject. The darker background not only make the nebula more visible, but also allows for longer exposure times before light pollution levels get too high. Because of this I was able to double the normal length of sub exposure to 1 minute, taking fifty in total.

To highlight the stars, a couple of extra minutes exposure using the was enough to bring out the colours in the line of stars beside the nebula.

Even with the extra light gathered, the final image stacked with Deep Sky Stacker took plenty of work in Photoshop to reveal the reds in the Flaming Star nebula and glowing cluster NGC 893 sitting opposite. Also revealed in the middle of the shot is the jewel-like Spider Nebula (IC 417) along with its prey, the tiny Fly Nebula (NGC 1931) seen just to the left. The two open clusters in the shot are M38 (top left) and M36 below.

Doubling or tripling the 50 minute exposure time would be necessary to improve the quality of the image. It looks a little grainy due to all the post-processing. But with the time I spent on processing, I think I’ll leave it at that!

Image details: Nikon D7000Nikkor 180mm f2.8 at f2.8. 50 minutes (50 x 60 seconds) at iso 800 using didymium filter, plus 2 minutes (4 x 30 seconds) at iso 800 using . Stacked with Deep Sky Stacker and tracked with barn door tracker.

The wide angle shot below, taken at 35mm a few weeks ago, puts the 180mm shot in context…

Auriga wied field taken at 35mm

Orion nebula revisited

Orion Nebula with barndoor trackerThe plan was to capture the flaming star nebula in Auriga last night, with it being overhead. I set the tracker up, took a few shots and immediately realised just how faint it was!.. As an antidote to this disappointment, I aimed the camera at the brightest nebula in the sky, the Great Orion Nebula.

I was able to add another 60 shots to the 112 I already had from last years efforts. I had reworked the 56 minute image several times, improving the results each time as my post processing techniques have developed.

The sequence below shows a progression from single 30 second photo, up to the latest image of 1 hour 26 minutes. There’s a big jump in image quality at each stage, with the latest image being much sharper due to the improved barn door tracker design. I also managed to find a more pleasing colour balance compared to the slightly muddied earlier versions.

Orion Nebula image processing sequenceImage details: Nikon D7000Nikkor 180mm f2.8 at f2.8. 1 hour 26 minutes (172 x 30 seconds) at iso 800. Using didymium filter. Stacked with Deep Sky Stacker and tracked with barn door tracker.

Evolution of comet Lovejoy

Despite being chilled to the bone on more than one occasion, tracking comet Lovejoy over the past month has been a great experience. It was, and still is, a stunning comet. Shooting Lovejoy on a total of 10 occasions over the last month with varying levels of success, I’ve stitched together the best of the bunch to show how the comet has evolved over time…

Nikon 180mm f2.8 D810aFor the earlier shoots I experimented with different exposure lengths (15-60 seconds), different ISO levels (800-1600), different lenses and different focal lengths (50mm, 85mm and 180mm). This was probably not the best tactic as the best results came from a 12 mile trip to darker skies on the 24th, using the tried and tested settings of 30 second exposures at iso 800 with the 180mm/f.2.8 lens. The image quality is visibly better in this shot mainly because the comet was near zenith so less post-processing was needed to remove the effects of light pollution…

Comet Lovejoy 2015 star trackerImage details: Nikon D7000Nikkor 180mm f2.8 at f2.8. 5 minutes (10 x 30 seconds) at iso 800. Using didymium filter. Stacked with Deep Sky Stacker and tracked with barn door tracker.

Comet Lovejoy with blue tailAs Lovejoy recedes further from Earth, its movement through the sky also appears slower. So although it’s starting to fade, it allows for many more exposures before the movement becomes an issue with the stacking. For example this 14 minute exposure from the 6th February vs. the 4 minute exposure on the 13th January.

In the recent images from early February you can clearly see the huge dust tail curving as the comet passes around the Sun.

Image details: Nikon D7000Nikkor 180mm f2.8 at f2.8. 14 minutes (28 x 30 seconds) at iso 800. Using didymium filter. Stacked with Deep Sky Stacker and tracked with barn door tracker.

I’ll no doubt take more shots of Lovejoy, but as can be seen in the most recent image from the 10th of February, the tail seems significantly dimmer now. Whether this is just another fluctuation in the structure of the tail, or a more significant decline, we’ll have to wait and see.

So I’m left with a series of shots showing comet Lovejoy’s evolution, along with a very full hard drive!.. Let’s hope the next comet Terry Lovejoy discovers is as good as this one.


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Samyang 85mm f1.4 lens..

astrophotography with Samyang Rokinon 85mm f1.4On a side note, the Samyang 85mm f1.4 lens I bought specifically for the job of imaging the comet proved to be no match for the trusty Nikkor 180mm f2.8. Unlike the results with comet Jacques, the tactic of maximum light gathering didn’t pay off this time. The lens may prove to be better suited to other subjects, but I’m not convinced as the coma was very noticeable even when stopped down. I think the ultra sharp Nikkor 85mm f1.8 G is the way forward at this focal length.

Image details: Nikon D7000Samyang/Rokinon 85mm f1.4 at f2.8. 4 minutes (16 x 15 seconds) at iso 800. Using didymium filter. Stacked with Deep Sky Stacker and tracked with barn door tracker

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Comet Lovejoy update 17th February…

Comet Lovejoy 2015 passes the Little Dumbell NebulaWith the skies finally clear after a week of cloud, I jumped at the chance to capture another shot of Lovejoy as it passed by the Little Dumbbell Nebula (M76). The planetary nebula is so tiny and faint that it’s considered one of the trickiest objects in the Messier catalogue to observe. The comet itself is definitely fading now, with the tail in particular much harder to pick up.

Image details: Nikon D7000Nikkor 180mm f2.8 at f2.8. 12 minutes (24 x 30 seconds) at iso 800. Using didymium filter. Stacked with Deep Sky Stacker and tracked with barn door tracker.

Auriga

Auriga with nikon 35mm f1.8 G lens

Imaging full constellations is something I’ve been itching to do since trying the new softon filter. So last night I set off in search of some darker skies armed with a borrowed Nikon 35mm f/1.8G lens. The constellation of Auriga was the target as it’s perfectly placed overhead at this time of year, and imaging large targets overhead is much preferred. (Trying to remove gradients from targets lower down is a real nightmare).

With an exposure time of 22 minutes, the detail visible in the shot is pretty impressive. The centre of Auriga holds two open clusters, M36 and M38, which sit beside a couple of faint nebulae; the Flaming Star nebula, and the less catchy IC410 – an area which could be an excellent target for the 180mm lens at some point.

The lens itself worked like a charm. Stopped own to f4 it’s super sharp, and the light weight makes it easy on the barn door tracker (200g vs 800g for the 180mm). I also had a pleasant surprise when it came to stacking the images as I realised I’d also caught the California nebula in the upper right of the shot!

Hoya Softon A filter for astro  imagingTo get the glowing star effect I took nine 2 minute photos without the filter, then two shots with the softon filter in place. I stacked these separately in DSS and combined them in Photoshop with the softon layer set to ‘screen’.

This side-by-side caparison of 2 minute shots of Capella demonstrates the filters effect. The medium to bright stars stand out much more, as well as their colours. The filter also dims the background stars making the constellations pop out even more.

Image details: Nikon D7000Nikkor 35mm f1.8G at f4. 18 minutes (9 x 2 minutes) at iso 800 using didymium filter, plus 4 minutes (2 x 2 minutes) at iso 800 using softon filter. Stacked with Deep Sky Stacker and Photoshop. Tracked with barn door tracker.