Tuesday, December 11, 2012

Early Conjunctions


A 6am start at -4 degrees is not always my idea of fun, but when I pulled up at the top of a nearby hill I was greeted with this spectacular view of a crescent Moon next to Venus, with the elusive planet Mercury burning through the low mist near the horizon. This slightly overexposed shot shows what is called "Earth Shine" on the lunar disc. Just as a full Moon reflect the sun back to us on Earth at night, the Earth also reflects light back to the Moon. In fact the Full Earth on the Moon would seen 100x brighter than a Full Moon on Earth - the result being the illumination of the "Dark Side" of the Lunar surface - easily seen with the naked eye, but more tricky to get on camera.




  With a shorter exposure we get the instantly recognisable crescent phase of the Moon. Tomorrow morning though this will have slid across the sky to just below Mercury, and at only ~2% illumination will be a fine sight ... if you can catch it!




This morning was more special than normal astronomically though (and the reason I hauled myself out of bed and into the cold) because you could see 5 planets at once with just your naked eye. Here we can see Mercury (bottom left), Venus (left of Moon), Earth (obviously!) and Saturn (brightest "star" towards the top right) as well as Jupiter (behind me, so not on the photograph). Venus shines at an incredible x23 the brightness of Mercury, but more impressive is Saturn - at 10x the distance away from us as the Sun is, it is still only x5 fainter than Mercury. Jupiter on the other hand is the largest planet in the solar system, and although very bright, is actually only half way to Saturn, which is itself only half way to Uranus. With most of the planets packed within the orbit of Jupiter, this just enhances the vast and desolate nature of our Solar System, yet that is nothing compared to our galaxy and the universe beyond.


Wednesday, November 28, 2012

Moon and Jupiter Conjunction

The Moon and Jupiter can be seen in close proximity tonight in the night sky, and with a pair of binoculars you can easily pick out the moons of Jupiter (Europa, Io, Ganymede & Callisto from Left to Right). Whilst the Moon looks big Jupiter is over 40 times larger, but being 1500x farther away at 609 million km it looks pretty small here - but still a discernible disk. Just like Jupiter, its biggest satellites are super-sized too at up to nearly twice the size of ours. So grab a pair of binoculars and gaze upon a another world and its moons over a third of a billion miles away .....


This image was taken with a Skywatcher 80ED and Canon 7D DLSR. 3 exposures were taken for the Moon (1/200s ISO100), Jupiter's disk (1/1000s ISO3200) and Jupiter's moons (1/125s ISO6400) and composited together in Photoshop to give a result not too dissimilar to that through binoculars.

Friday, August 31, 2012

Once in a Blue Moon

I had a piece of rare spare time last evening, and luck seemed to be on my side as the skies had cleared after a fairly wet and miserable few days. From the comfort of my sofa I could see the full moon rising from behind the nearby oak trees that line the hill I live on, and whilst most astronomer will curse at the sight of it, I decided to embrace the opportunity, timing, and recent passing of the legend that is Neil Armstrong to set up my telescope to take a closer look.

The great thing about the moon is that it's easy to find, easy to see, and fairly easy to take pictures of to. After a spot of visual observing I was focussing away and taking a few frames with a view of seeing if I could tease out the colouration that I could quite clearly see with my binoculars and telescope. The image below is what I captured, carefully processed in Photoshop to being out the subtle colours on its surface without it looking too unreal.

Full Moon - 31st August 2012, Skywatcher 80ED, Canon 7D, ISO100 1/160s.  Mare Tranquillitatis (the Sea of Tranquility) can be seen with a blue tinge at the mid right of center..


The hint of colours on this image are all very real - indeed you can see the brightest bluish tinges with just a pair of binoculars on a suitable night - and they tell us something about that distant world that until 43 years ago no human had set foot upon.
Just as emeralds are green and sapphires are blue, most minerals have their own distinctive colour. Normally these are quite dull, and it is only the skill of a jeweller that can turn them into such brilliant stones that are worthy of being embed into rings, but their colour still belies their presence and potential. In the case of the moon, the blue tinge comes from an abundance of Titanium Oxide and Iron, whilst the orange areas are lacking in these minerals.

The full moon also reveals majestic white rays the cross almost the entire globe. Normally hidden from view, the overhead sun reflects more clearly off these deposits than the darker ancient lava plains underlying them during a full moon. The most prominent being that of Tycho in the lower-left, and Copernicus in the mid-top-left of the image. The rays from Tycho can be followed in a curve right across the disc, revealing the Moon is indeed a spherical object and not just a two dimensional disk hanging in the night sky.

There is also something more special about this full moon that I did know know whilst I was out observing. It is what is popularly termed a Blue Moon - meaning it is the second full moon seen in the same month, the first in this case having been on August 1st. This event is quite rare to observe in the UK- they occur only twice every three years and the weather has to be on your side too! One can easily see how this name can be linked to the old phrase "Once in a Blue Moon" that is used to signify a rarity of occurrence.

My original goal was simply to gaze upon a world that, in my mind, has been too long neglected by Man. In capturing the colouration of the moon in my photograph and the coincidence of if being a Blue Moon, with blue colouration, and that colouration being present in Mare Tranquillitatis where Neil Armstrong and Buzz Aldrin first planted the feet of man beyond our own world was as beautiful a circle as viewing the moon itself.

Sunday, June 17, 2012

Pits and Spots

I recently joined Mansfield & Sutton Astronomical Society, and the other month I helped out with a solar observing outreach event at Pleasley Pit - an old coal mine that has been lovingly restored and open for visitors to see what life was like down the pit as well as supporting a nature reserve on its surrounding land. The pit is sited on top of a hill, so there were fantastic views to the south towards the distant wind turbines east of Mansfield as well as perfect conditions for solar observing. 






Because of the weather the turnout was really good - one 9 year old girl kept coming back again and again for "just one more look" at the sun - she told me how she had build solar system mobiles and demonstrated the seasons on Earth using a pencil-pierced paper plate in class at school. Kids are some of the most rewarding and challenging people to engage at outreach projects as they either know more than you, or ask questions that seem so simple and common-place on the surface, yet never so simple to answer. "How close to the sun could you go before you caught fire". Hopefully some of her enthusiasm will stay with her into later life.

Views were had in both white light and through a 50mm H-Alpha Solarscope telescope - the latter providing incredible arcing prominences, filaments, and a generally rather active sun. Spurned on by the morning events, I finished off building my own white light filter out of a sheet of Baarder solar film, packet of Shreddies, and obligatory Duck Tape. Once fitted to my trusty ED80 with my new Canon 7D I managed to focus and grab a few dozen frames before the little 'un decided he'd had enough of me taking more interest of a few bits of metal and glass than him, and started to cause mischief of one sort or another.

This is the result of 25 frames from the ED80 and prime focus 7D combination - ISO100@1/640s.


I'm quite impressed with the results really considering it's only a stack of 25 images - the 7D has managed to pick up the granulation on the surface pretty well as well as lighter filamentous areas of disturbance best seen on the limb past the far right large spot and similarly on the left limb too. No idea what these are called though! You also get the darkening limb effect caused by the fact that you are looking through more of the solar "atmosphere" than the point in the centre of the disk.

The sunspots have come out really well though - the four Active Regions groups (AR's) are (from left to right), AR's 1492, 1490, 1488, and 1486 - AR1490 harbouring a C-Class solar flare (a low to medium strength class eruption of charged particles from the solar surface).

The image was aligned, stacked, and initially processed in Iris, then final tweaks, balancing, and framing in Photoshop. The colour is "as shot" - I was going to colourise it, but could not decide which hue of orange to use without it looking somewhat "odd".

Wednesday, February 09, 2011

Northern Star Trails

It's been quite some time since I've last imaged anything astronomical, so to get back into the swing of things I thought I'd tackle something relatively simple .... or so I thought.

Capturing star trails is a great was of seeing the night sky in motion. It requires a fairly simple set up, and can be done with most modern digital camera pretty easily. I set my 20D up in the shelter of my daughters Wendy house, mounted on a Gorilla tripod, pointed it up to the side of Polaris, and left it to it overnight capturing 30 second frames continuously.

In the image below, Alpha Ursa Minor (Polaris) is the tight curl at the top left, Beta Ursa Minor is the next bright reddish trail in the middle of the frame. The next bright red trail 3/4 of the way across the frame is Alpha Ursa Major (Dubhe) with other members of Ursa Major bunching up to the right of the frame. You can also see one remaining airplane tracking across to the top right, though there were 4 other trails on the original data set (removed in the processing) which is quite impressive considering the small area of sky this image covers. If you watch the movie (here
on YouTube - make sure you watch at 360p resolution) you should also see the wonderful double of Zeta Ursa Major (Mizar) slide around the view.



You need a nice wide angle for star trails. This was taken with a 28mm lens (which translates to a 42mm lens on a full frame camera) so is rather on the tight side. I chose this lens over my 10mm wide angle as I wanted to use the Astronomix CLS light pollution filter - the view to the North is directly over a set of street lights - but the 2" filter would not fit on the wide angle lens. Powered by an external lead acid battery and a battery adaptor, I knew I could set it on continuous shooting mode at 30s exposures and not run out of juice half way though the night. To fit all the frames onto my SD card though I needed to shoot medium size JPG's - the images would be downsized anyway so I did not need the higher resolution, but a shame to lose the dynamic range of a RAW image, but that was the price I had to pay for the size SD card I had. The camera was then left to its own devices over night whilst I got some sleep.

It was a cold night and by the morning, although in a sheltered spot, the lens had quite a bit of condensation on it as well as spots of frost. A quick examination of the frames showed that the quality did deteriorate around 2am
(seen as a fading of the stars trail as they rotate clockwise) but at least the stars were still there. My next project will be to build a lens warmer (dew heater) out of an old toaster and a few bits of fabric :)

I took dark, bias, and flat frames as usual, except these were also recorded in jpg format rather than my regular raw format. The unfortunate offshoot of this is the DeepSkyStacker would not pre-process the frames to calibrate them before stacking (DSS will correct colour balance via flats which is very advantageous when using a CLS filter). Without the use of DSS I turned to Iris - a very powerful, but not so user friendly package. It still did a pretty good job in calibration, but would not automatically colour balance the results and took a lot more manual labour for the same results I would have got in DSS with minor intervention. I also used Iris to composite the final trail shot as well as producing doubly binned (so the processed frames were 1/4 original size) frames for an animation. The animation frames were further treated by running them through a photoshop action to apply a maximise filter (posterise the stars a bit so they are not lost in the compression process), resize, and get the correct aspect ratio for YouTube to be happy. Even then, the compression really kills the definition of the stars, but you get the idea. The original quality wmv movie is soooo much better!

I'm fairly pleased with the final result - it nicely shows how Polaris is just off the Earths axis of rotation as well as capturing Ursa Minor and a part of Ursa Major. There was some movement of the tripod early in the exposure, shown up as a kink in the trail most noticeable at Polaris, and the bathroom light caused the lens flare across the frame - red because the CLS filter has removed the yellow colour from the flare. I did learn that something simple like this can prove to be more complex than originally thought. Most of the pain came from the use of the CLS filter and shooting JPG's, but from my location not using the filter is not an option, though I shall invest in a larger CS card and shoot in RAW next time :)

Tuesday, October 28, 2008

M45 - The Seven Sisters

This is a target I've been longing to bag for quite some time now. It's one of the most well known open clusters in the northern hemisphere, and an absolute beauty to behold in a pair of binoculars or wide field telescope. One thing you cannot see in this way though is the nebulosity that surrounds and envelopes the cluster - only a very large telescope or long exposure image will reveal the beauty of that.

Also know as Subaru in Japan (yes, the same as in the car, which
incidentally has only 6 stars on its logo), the Pleiades lies 440 light years away in Taurus, and is composed of over a thousand 100 million year old hot blue stars. These stars are shining upon a nearly (though unrelated) cloud of interstellar dust, which in turn then reflects the blue light back to us, and it is this that we see here as a faint nebulosity surrounding the stars.

With the clocks falling back an hour into GMT (where they should be in my book!) I took the opportunity to get out in the back garden to do some imaging. I was intending to have a go at the Great Andromeda Galaxy, but I saw the Pleiades rising above the hedge line and I could not resist! In hindsight I should have, as being only a shade over 30 degrees up in the mirk of Bristol (and more importantly the street light behind the hedge) I was never going to get the best out of my kit - the attenuation of light must have been pretty harsh to be honest. That aside, I'm somewhat pleased with the result - another keeper!


During processing I must have tried about half a dozen different curve manipulation paths on this one, with each run giving me a completely different result. I now firmly believe in working in the luminance channel separately from any colour channels even with one shot colour images as it helps enormously - after all it is the luminance that gives the details, not the colour. This is actually normal practice in CCD imaging, where you get the best, deepest, smoothest, and longest exposures for the luminance, then use 2x2 binning for the colour data.

In PixInsight this can easily be achieved on an already RGB image utilising the LAB colour space (ie, the luminance channel is processed separately from the 2 colour channels). In this case it allowed me to pull out the faint nebulosity without blowing the colours way out of proportion - especially the blues. In the end I settled for my own processed luminance image, and the colour data coming from an image off the Internet. The result is a tinted version of my captured data, and thus all of the details present were actually captured by my camera and only the hues "synthetic".

I'll settle for Andromeda another day .....

Sunday, October 26, 2008

Scope & Camera Finally Meet!

On the night of the Lunar imaging that I posted previously, I also finally put my 20D on the end of my telescope at prime focus. I was happy I knew how the camera operated, and I had been playing with using my laptop to control the camera via a custom cable release controlled by the parallel port - which basically meant the laptop held the bulb down and did the exposure counting rather than me and my thumb :) I was ready for the next step in my imaging journey.

I needed something bright and easy to start with, so the first target was the Great Globular Cluster in Hercules - M13. It's one the brightest globular clusters in the Northern Hemisphere and is just visible to the naked eye on a
good night. Although easily seem with 10x50 binoculars, the stars only really start to resolve out of the blob when you turn a telescope towards it. With hundreds of thousands of stars present, the more aperture you have to hand the more stars you can resolve. Visually, some people claim there are patterns inside the cluster - a propeller is quite often cited - though I do wonder if it's just a case of the classic "averted imagination" (which is our local societies take on the averted vision technique that some of the experienced observers tend to use when seeing things nobody else can!). I also have horrendous memories at university being made to count the number of stars in the cluster using a magnifying glass .... thank god for the invention of computers to do such tedious things for you! Anyway, on with the first image!


This image is a crop from a larger frame, and you can also see a small friend to the north east of the cluster called NGC 6207 - a 12th magnitude edge on galaxy. This is just a line of sight effect mind and the two are not related in any other way than their apparent position in the sky.

The image is a summation of 13 two and half minute exposures, stacked in Deep Sky Stacker, and given the obligatory PixInsight and Photoshop treatment. I'm finding now that I need to do around 3 attempts before I get one that I find satisfactory - and almost always the first one is never the best.

I felt I was on a roll by this time in the evenings preceedings. M13, a lunar mosaic, what more could I want .... Well, I really wanted to try to capture the North American Nebula, but knew my camera was not the most sensitive in the Hydrogen Alpha light that this nebula throws out in spades. This didn't stop me from wanting to have a go though! Unfortunately, I quickly realised that ther was no way I could spot the nebula in either the finder, 10x50's, or telescope itself (as mentioned in some of my previous posts) so I needed to have a leap of faith. I had a rough idea from a star chart I had to hand, but with only the finder to line up, it was a serious case of "point and hope"

Well, lady luck was obviously on my side again, as extremely faintly in the background of the image data was a nebula bursting to get out. It needed some heavy proce
ssing, but luckily it seemed to take it well, and this was the result.

I was a very happy man when I teased this data out of the set! It's a stack of 12 two and a half minute lights, and you can see quite a bit of detail in there when you start to look. Yes, a little noisy, but that's to be expected with the ISO, processing aggressiveness, and low frame count, but definitely a keeper :)

I performed the normal DSS stacking (with flats, darks, and bias frames), a hefty session in PixInsight, and a fair bit of tweaking, layering, and exposure balancing in Photoshop to get the best out of the data.

I'm rather proud of the result to be honest! The framing could not have been better (there's no cropping here). All in all the most successful imaging night to date! I suspect next time I won't be as lucky :(

Tuesday, September 30, 2008

Return To The Moon

It's been a while since I last pointed my trusty ToUCam Pro webcam at the Moons surface - too long to be honest! I find there's something very satisfying in this day and age of expensive equipment of putting a humble webcam at the prime focus of my telescope. The instant gratification of seeing a small section of the Moon surface shimmering away on your laptop screen cannot be underestimated in my book!

I was having a torrid time with my 20D's first outing - I always forget something, and this time it was the USB cable to connect it to my laptop for long exposures. The night was superb, and once the Moon had risen over the observatory dome I couldn't help but have a go at imaging it "for old times sake", plus I know that at least I could take home something good from the night!

Times have changed since I first started webcaming - we can now update the firmware on the ToUCam to remove the automatic sharpening, and even remove the automatic debayering algorithm as well. The result? Much smoother, sharper images that give fantastic results. Unfortunately I did not pay enough attention to getting the correct exposure :( It's all too easy with the Moon to get this wrong due to its huge dynamic range - ideally you should take a number of exposures and blend them together to get best results, but on this night I as just wanting to grab a quick image. I really should learn that this is not a good idea! Anyway, here's the resulting image:


Still, I'm impressed with the result. Another great thing about webcams is that a mosaic stacks up the mega-pixels pretty darn fast! Back in 2002 I spent an evening with my 8" Meade Starfinder and 2x Barlow lens capturing over 60 sets of avi files to produce a massive image that I had printed out and now proudly hangs on my wall at an impressive 2 foot square. I think it took me well over a week to process that bad boy! It's like having my own personal Lunar Atlas on the wall, and I love it :)

Anyway, back to this image! Now, I don't know why, but Registax really, really, winds me up! It just never quite works the way I want it to. For this image I simply wanted to multi-point stack all 8 frames using sigma clipping. I gave up on the multi-point aspect as it just did not work :( I'm not sure I really needed it anyway for this project. The stacked images were then dumped into Photoshop, clipped to a clean edge, feathered out, and mosaiced together. I used the exposure image adjuster to level out the variable transparency that occurred during the capturing process, and a liberal use of the eraser tool removed a few alignment oddities. With a clean base image, I ran the smart sharpen filter to bring out a bit of the detail (I'd love to use a deconvolution filter in Photoshop, but I don't have one) and then ran three sets of high-pass filtering of reducing filter size (7.5, 3.2, 1.4) to increase the tonal range and contrast without introducing too much noise into the final image. The end result, a rather pleasing lunar mosaic and an urge to do it again - but this time properly :)

Monday, September 29, 2008

Cygnus Widefield

Continuing with my 20D and 50mm setup, I moved on from the Double Cluster to the region around Deneb (alpha Cygni) and the nebula with the most canny resemblance to its namesake, the North American Nebula. I've tried this region out with my 10D in the past, and have been pleasantly surprised with the results, so I was hoping for better things this time.

Set up in my back garden, equipped with an Astronomix CLS light pollution filter, I pointed the camera straight up and let it record 50 frames, each of 60 seconds - as with the Double Cluster, any longer and there was no benefit due to the quarter moon rising. Incidentally, while this was going on I actually undertook some visual observing for once! Lying on the sun lounger I worked my way around the familiar clusters and double stars of the summer sky, and also undertook some detailed observations of the Lunar terminator as well (more on that in another post perhaps). Anyway, a couple of hours later and the light and dark frames had been safely captured and I could retire for the night. Job done (for now!).

Stacking was done using the excellent Deep Sky
Stacker, and most of the processing with PixInsight LE and final composition and balancing with Photoshop. Yet again, I was impressed with what such humble equipment could achieve! There are just sooooo many stars in that region of the Milky Way! Here's the results at any rate.


Just as normal, I like to fire up Patrick Chevelley's excellent Cartes du Ciel (Sky Charts) to see what I've captured. NGC7000 was immediately obvious - being the brightest hydrogen alpha region in the area that was to be expected! There was also a massive cloud of stars just further down away from Deneb which I'm sure must have some name or designation ... it does contain NGC 7039 - an open cluster - but when seen in this image it looks hard not to think the cluster is just part of another, more massive, grouping out there. One assumes that NGC 7039 is gravitationally bound and the rest of the stars are just a line of sight efffect looking through the plane of the Milky Way. There even seem to be darker dust lanes just eating into the side and edging into the middle of the stellar collection in places. Before I go further, here's an annotated version to compare my notes with.



The Pelican nebula (IC 5070) and adjoining IC 5068 are readily visible, as is the wonderfully sounding (and looking) Butterfly Nebula (IC 1318). Definitely worth a closer look at some point in the future! Continuing past the Butterfly along the main body of Cygnus you come to the area that houses the Crescent Nebula - too small to be seen directly here, but the hydrogen alpha complex it lies in s visible as a small reddish blob. In fact, there is lots of nebulosity around this region, including IC 1311, but with the current response of my 20D to this hydrogen light, that's about all I'm going to be able to see for now.

One final capture was that of the edge of the Veil Nebula on the extreme right hand edge of the image - again, another future target to explore!

I'm rather enjoying this imaging lark - there's just so much that you can do without having to spend massive amounts of money on fancy kit. I've not even attached it to a telescope yet :) So, the next logical stop must be to use my ED80 refractor as a lens and shoot through it at prime focus .... we can then get a bit closer to a number of these interesting objects in the summer skies!

The Double Cluster

I finally splashed out on a Canon 20D from eBay to upgrade from my 10D - something I have been pondering over for a while now. Why? Well, the CCD is quite a step quieter than that of the 10D, there are obviously more pixels, and the price was pretty good as well! As much as I'd love to buy a new top of the range camera, for my astronomical needs it's not the best return on investment as the 20D upgrade.

Anyway, I set up in the back garden with just my trusty f/1.8 Canon 50mm lens mounted on a Vixen mount for tracking. I had just finished building a long exposure cable (parallel port to cable release) so my laptop can queue up a sequence of shots whilst I go indoors and keep warm, so I used that to capture 10 60 second frames of the Double Cluster in Perseus - spurred on after hearing a talk at the Bristol Astronomical Society about it. The quarter moon was not far away and raised the background level tremendously, but I could still cut through enough of it to capture the cluster.



I'm rather pleased with the results to be honest. Considering I was pushing it with ISO1600, the noise was relatively low - a lot lower than I would have got on the 10D at any rate.

What I didn't realise was that I'd actually captured the faintest of glimpses of IC 1805 and 1848 - slightly better known as the Heart and Soul nebula. It's really faint, and you can only just see it if your monitor is calibrated correctly, but it is definitely there! Here's an annotated version to show it better along with a few other surprise visitors in the frame! - Note: It appears that Blogger has re-compressed the JPG's after uploading, and the Heart and Soul nebulae are even harder to spot than before :(



The 20D (and other EOS Canon models) all have the intrinsic problem of the internal IR filter cut off curve being somewhat broad, causing hydrogen alpha to be clipped by well over 50% I believe. One day I may pluck up the guts to modify it and replace with a more forgiving IR filter, but that's for another day! Until then, these lovely hydrogen alpha clouds are going to remain a little elusive to me!

Some people say that imaging is not "true" astronomy, but I learn more about the night sky from my own adventures in astrophotography that I do from any book or magazine. The realisation of just how faint some things are and how big or small they are from a picture give much more understanding and weight than just a hard magnitude or arcsecond number - or at least it does for me! I like to think of it as Practical Learning :) I certainly would not have though to go looking for the other Stock clusters if it wasn't for capturing then whilst imaging something completly different .... nothing beats the knowledge that you have captured photons from far away places, travelling for more years than one cares to imagine, and have preserved their legacy for ever more in a photograph hanging on your wall.

Thursday, August 14, 2008

Partial Eclipse - 1st August 2008

I completely forgot about the (partial from the UK) eclipse this year, so I was not prepared at all for the occasion. This, however, turned out to be a blessing in disguise as the results were totally unexpected!

Whilst getting ready to go to a wedding, the best I could do was dash outside when it looked sunny and snap a couple of pictures on the most insensitive setting my 10D could muster - not something usually done in this hobby! - but even that was not going to be good enough for direct solar imaging without any filtering.

Now, I must just say that direct solar observing should not be undertaken through any optics directly (including just your eyes) . The way I got around this was to pre-focus on some distant woodlands, lock down into manual focus mode, and use projection to make sure I had the sun in the field of view. When the clouds started to roll over (and there were a lot of them that day!) I just snapped away in an attempt to catch just a few frames of the New Moon sliding across the face of the disc.

This became addictive - popping outside when I should be loading up the car to get to a wedding 100 miles away - and I knew I was going to get myself into trouble :) But, it was worth the effort, even if glimpses of the sun were fleeting and I did not directly observe the disc. It reminded me of Cornwall back in '99 and the total solar eclipse. My father and I went to the Headland Hotel on Fistral Beach in Newquay with his old home-made refractor to project the solar disc onto a small piece of card we took with us. It was cloudy (and rainy) for most of the time, but we caught glimpses of the solar disc being slowly "eaten" by the Moon. Just seconds before totality came, and the darkness overhead enveloped the thousands of people along the beach, the clouds parted for us to witness totality in all its splendour. I can vividly remember seeing deep red flares around the edge of the occluding Moon through the telescope, and the myriad of flashbulbs going off around the bay like it was some sort of rock concert - complete with cheering, shouting, and hollering. It turned out we were extremely lucky that day, pretty much everywhere else in the far south west did not see that spectacle. We were honoured.

An interesting part of these images to note about these images is how the clouds interacted with the sunlight. With such short exposures, the refraction of the sunlight through the clouds could be captured as a mini halo around the sun. When cropped carefully, you can see the similarity between the clouds cradling the solar disc and, on a far greater scale, the Great Orion Nebula cradling stars in its stellar nursery. I'm always in awe at how nature seems to repeat itself over such vastly differing scales.

Tuesday, August 12, 2008

M57 - The Great Ring Nebula


M57 is a probably one of the best know planetary nebulas in the night sky, and observing it with pretty much any telescope will tell you why. Whether it's just a tiny Polo in the sky in an 80mm refractor, or a birds nest of filaments weaved into a ring through an 18" Dobsonian, it never fails to inject intrigue into the observer as to what exactly happened to that ageing star. Did any exotic life forms had their existence extinguished in, what must have been, a catastrophic shedding of the stars outer atmosphere as it strived to find a new equilibrium after exhausting its main hydrogen reserves? Where there even any planets in the system to witness this metamorphosis of what was most likely a pretty regular star into one of natures finest and strangest objects, a white dwarf.

With dark enough skies, and a large enough telescope, you may even be able to glimpse this white dwarf at the centre of the ring, shining at a mere magnitude 15.7, but what a tiny object to be able to see at such a distance of 2300 light years!

We had the good fortune to be able to image this magnificent object using the Faulkes Telescope as part of ties between the Bristol Astronomical Society and the Faulkes team. This was the first "regular" object that we've imaged with the robotic telescope in Hawaii - normally we image more obscure groups of galaxies from the Hickson catalogue - and boy were we in for a treat!

We took ten 60 second exposures though red, green, and blue filters, and combining just the reds quickly showed we had caught more than we'd bargained for! By stretching the resulting image one could easily make out a very faint glow of nebulosity surrounding the main ring - material that was shed before the final stellar collapse and outpouring that we see the result of visually. In fact there is another, even fainter ring of material around this outer shell, but we were not able to record that with the exposure times we obtained. The challenge in processing this object was going to be to try to show this faint "nebulosity" alongside the traditional Ring.

Well, here is my result:


Now, I must have messed up at some point because the stars have all lost their differing hues - something to go back and fix at a later date - but I am very pleased at the result. Something interesting to note is that we managed to resolve the 3 stars just above the outer faint section directly above the ring - quite often these will blend together into one "bloated" star, so it goes to show the quality of the optics the Faulkes Telescope has.

Now on to the details of processing:

The initial processing was achieved using good old Deep Sky Stacker, giving 3 master RGB channels that I could tweak in PixInsightLE. The red was processed extensively to get a nice core ring image to use as a luminance channel - just curves and a little wavelet processing to bring out the knots in the gas sufficed. A second red image was then stretched to its limit to bring out the outer nebulosity, which needed a little noise reduction to smooth out the grainy nature of the tenuous gas. These 2 were blended together in Photoshop as a source luminance channel, then the "regular" RGB frames were added to produce the final image. Hot pixels, lines, and other artefacts where then removed with the spot healing tool before the final colour balance was achieved. I initially thought the ring seemed rather mute in colour, but I actually like it that way - more akin to what one would see through a telescope rather than in a glossy magazine.

Tuesday, May 27, 2008

High Dynamic Range Moon

The eye and brain has an amazing ability to be able to perceive things that are intrinsically very bright and also very faint at the same time - and in astronomy this is most evident as one looks at the crescent Moon.

Once the sky darkens when the Moon is just a few days old and sinking fast after the setting sun, one can easily glimpse the phenomena that is Earth Shine. This is where the light from our star, the Sun, is reflected off the still sunlit parts of the Earth's surface, and is reflected back out towards the Moon. It then reflects for a second time back to the Earth whereby we can juts perceive it as a ghostly image of the lunar surface. The effect is most pronounced early and late in the Moons cycle as the bright Sun lit crescent is small compared to the faint Earth lit globe.

Note, you must have your monitor correctly calibrated to see this properly, otherwise it might all look a little bit dark. Try this website to get a rough setup.


Digital cameras are not as good as the eye in this respect. Take a picture of the Moon and you'll find that you cannot correctly expose both the darker Earth lit surface and the bright Sun lit crescent at the same time. Why is this? Well, a digital camera has what we call a fixed dynamic range. That is, it has a finite range of brightnesses that it can capture in one go, and it's generally not as good the the Good 'Ole Eye!

To get around this problem, one can take multiple images at different exposures and use a photo package such as Photoshop to blend them together to create what has been coined a "High Dynamic Range" (or HDR) image. I won't go into detail here about how I did it, just do a Google for HDR blending. In my case, I took exposures from 0.25 to 30 seconds through my ED80 'scope and blended them together. The result was to capture both the brightest part of the Mo
on (magnitude -7.2 according to calsky) to the faintest star just to the top left of the Moon at magnitude 10.1 (according to Sky Charts). Quite some range!

Here's a tighter crop of the Moon showing more of the details of the "shadowed" Maria - note that it looks just like a filtered down full moon as the light source is, for all intents and purposes, coming from the same angle as that for a full moon - albeit with somewhat less illumination. Easily visible are the major Maria, Tycho with its outspread rays, Copernicus, and the "bright" Aristarchus near the far left limb.

Tuesday, May 13, 2008

Saturn

As part of our Mercury evening at Bristol Astronomical Societies observatory last week we took the time to image Saturn whilst the darkness kicked in ready for some deeper sky observing.

We used the prime focus (or Newtonian focus for you purists!) webcam imaging with my ToUCam Pro and IR filter. After initial focusing the firmware was updated to
utilise the Colour-RAW mod using WcRmac for the best results we can get from this webcam.

After experimenting with a 2x, 4x, and no barlow lens, the 2x produced the best overall results given the steady (but rather hazy) conditions. I rather like the result! Depending on which monitor/TFT I view this on, it can look a little dark .... I think I need to calibrate my monitors!


Technical Details: Cyril Swindon is a 12" Newtonian reflector with a newly furbished motor and fine RA controller which worked flawlessly. For such a large scope, it was surprisingly easy to aim, focus, and fine track. 2000 frames were captured, and just under 1000 used to create the final stack. The resulting TIFF was then exported and wavelets, colour balancing, noise reduction, rotation, and cropping was performed with PixInsightLE (which gives, in my opinion, far more controllable results than Registax).

Monday, May 12, 2008

The Innermost Planet

I've only ever seen Mercury once before, and it was a rather special occasion. That evening my fiancé and I watched the International Space Station skim overhead, and spotted all the planets out to Saturn in one sitting.

Mercury was hard to spot initially, but from our high vantage point we finally saw it come out of the murk over Bristol. Venus was easy, beaten only be Earth, and Mars was obvious with its redness in the evening sky. Jupiter and Saturn were obvious to the trained eye that noticed the intruding "stars" in their host constellation, but easily pointed out.

Last week our local astronomical society took the chance the weather gave to us to go out for a Mercury spotting session - possibly the only chance we'd get this year. This was the first image taken after sundown, and the scene was just beautiful. From the low lying orange clouds on the horizon to the deep blue sky overhead and the Moon with its Earth shine reminding us how bright we must seen to our watching companion.

In this image, Mercury can be seen nestling down towards the orange hazr in the bottom right, and the stars Alnath and Hassaleh can be seen just above the moon and to the right of the moon respectively.


This was the first of a number of targets that night ... so more to follow soon ....

Sunday, May 11, 2008

We had some pretty impressive electrical and thunder storms the other night, and not to miss a trick, I set up my 10D on a tripod pointing out the window and set it going, hoping to capture some lightning - confidence was high considering the rate at which it was forking down to Earth.

Out of over 120 frames taken, I captured lightning on about 6 of them. This was the best by far - and what a stonker it was too! It seemed to weave around in circles, in and out of the clouds, before making a very decisive beeline down to Earth. I think I was lucky to get the result I did, but I'm not complaining :)

Whilst watching the storm, there were 2 strikes about 40 seconds apart that forked down pretty close by, but behind the houses over the road. Straight after hitting home there was the most eerie of sights - a large hemisphere of electric blue rose up from behind the house, flickering ever so slightly over a period of about two seconds before quickly shrinking down and being replaced with an auroral-green dome which lasted about a second before fading. This happened twice in a row at the same spot .... I wonder if it stuck some power lines or similar - I'll never know, but it really gave me shivers down my spine when I saw it.


Few technical details now. All my images were taken with a 28mm lens stopped right down to get the longest exposure I could (8 seconds) whilst keeping the sky dark, but not black. This way, when lightning did strike, firstly it would not be washed out by the sky, and secondly with the small aperture it would not bloom too much (the lightning is *very* bright compared to the ambient light levels). It was just down to luck after that - though I could see which area of sky was producing the best strikes so at least I would have a fighting chance!

Thursday, February 21, 2008

The Great Orion Nebula

This is probably the most looked at telescopic "deep sky" object in the night sky of the northern hemisphere, though Deep Sky may not be the best description of the object as it's really rather bright as far as these things go! Visually you can see a definitive glow of gas in the centre of Orion's belt - you can certainly tell it's not stellar in nature. Through the eyepiece, I tend to see a tenuous curls of green glowing gas, studded with the central stars that make up the trapezium. The low elevation in the sky makes viewing it quite different every time depending on the local sky conditions, and the fainter outer curls seem to pass in and out of my vision as I look. Sometimes I wonder if I'm wishing the details to come out, but the structure is very much real!

I have tried to image M42 in the past with a modified webcam - this bought out the central region not too unlike what I could see visually, but with the added dimension of colour - a lovely pinky red tint. Moving on a few years, I now have my trusty Canon 10D, and with a motorised Vixen mount on loan I though I'd point my ED80 refractor towards the hunters belt to see what I could capture with a DLSR set up.

Boy, I was not disappointed by the results! From the first single frame I knew that I was going to get a very satisfying result! I proceeded to take a series of 40 30 second exposures, complimenting them with 20 dark frames, and ran it through Deep Sky Stacker and PixInsightLE to bring out this result. It even captured the "Running Man" nebula, NGC1977, at the top of the frame. It is called such because the dark lanes running through the nebulosity look like a man running - something that is quite subtle on this image but still visible with some imagination! Depending on your monitor settings, you may be able to pick this out - a lot of TFT's tend not to have linear brightness intensities across all shades of grey so it may look a little dark.

This was a milestone for me, and a great little test for my camera, mount, and overall work flow. When I get my Astronomics CLS light pollution filter, I shall take longer subs and see just how far the nebulosity can be traced. For now though, more 30 second subs and a good set of flats can only enhance the image further ... I just need some more free time and a clear night :)

Saturn and its Closing Rings

I have not had a lot of time to observe over the past few months, but the opportunity came up the other week to get a telescope out to show my father in law some of the delights of the night sky. Top on the list was Saturn, and I was amazed to see just how much the rings have closed since I last got a good look at the ringed planet.

This image was taken with Bristol Astronomical Socities' newly donated 8" scope (thanks Jan!). It needs collimating, and the helical focuser has a bit of play in it, so a little attention will have to be paid to the scope to get it finely tuned. The result was still worth the effort though. I'm not sure on the make of the scope, but the mount is a Vixen, and it's pretty darn good at tracking too! The whole thing is made of aluminium, so it a lot lighter than my steel EQ5 mount - and thus infinitely more portable. It looks to be a good imaging platform for exposures of a minute or so with good polar alignment.


Wednesday, January 30, 2008

Hickson 19

More Faulkes data has landed in the Bristol Astronomical Societies inbox, and this time is that rather faint Hickson Compact Galaxy group 19. Faint being the understatement here - the brightest component being at magnitude 14.5! Luckily, the FingerLakes IMG42-40 camera on Faulkes North is more than up to the job with its rather sensitive 4 megapixel E2V CCD sensor. Unfortunately member HCG19c was just clipped of the top of the frame :(

Doing the usual Googling around the internet turned up a few familiar websites with images of HCG19 - again showing that detailed images of these galaxies are not readily available. Uncle Rod has an "amateur" image of the cluster using his Celestron Nexstar11GPS, e also have the DSS image on the Italian Uriland website, and the wonderfully useful Aladin brings up the "tech specs" of the grouping nicely.

As usual, the blue channel was a lot fainter than the red (which had the strongest signal) but the overall noise was a lot less that we have seen in the past, making it possible to pull an LRGB image out of it. The luminance channel was synthesized from balancing the intensity of all 30 frames in the 3 channels and processed for maximum detail (using deconvolution) and minimal noise. This was then used with the base red, green, and blue channels that were just stacked, white balanced via the star on the middle-left of the image, and aligned. All initial processing was performed in Iris, with PixInsight being used for multiple passes of GREYCStoration to remove as much noise as possible. I hope you like the results!

Wednesday, December 19, 2007

An Unexpected Journey - Comet 17P-Holmes

This was an unexpected journey for both me and the astronomical community. Comet Holmes burst onto the scene in October of this year to the delight of many an astronomer around the world. Telescopes were trained on Perseus and this receding visitor as it spread away from Earth on its long journey around the Solar System. I too wanted to get my telescope trained on this unusual beast, but my newly arrived daughter (giving me much, much more delight than a comet could ever do) meant all astronomical activities were put on hold. More on that later, but first the nitty-gritty technical details :)

This image is the result of 2279 8 second frames - giving a total of 5 hours, 3 minutes, and 52 seconds total integration time - taken between 28th October and 12th December 2007 with my trusty Canon 10D, 50mm f1.8 lens (operating at f2.0), stuck on a regular field tripod. This mosaic shows only 12 of the days between these dates to give a good spread without overlap. One can also see on this object the wonderfully large open cluster Mel20 in the heart of Perseus (the trapezoid above centre just below Holmes) as well as open cluster M34 towards the bottom right of the image.


With my daughter taking up most of my time at home, I quickly realised that the best I could muster was to stick my camera on a tripod in the garden, point it at Persues, and lock the shutter down in continuous shutter mode and hope for the best. The light pollution around my house is incredible, but this actually worked out OK. 8 seconds is as long as one can go with a 50mm lens on a tripod at that declination without trailing. Even at this exposure at f2.0 and ISO400, the background was easily saturating so longer exposures wouldn't have done a lot anyway.

It became an addictive exercise :) I would get in from work, set the camera up, and leave it running whilst I had my dinner and spend time with my daughter. Each night that was clear I was filling up my 1Gb card and rapidly filling up my hard drive!

I used Deep Sky Stacker to produce daily frame stacks (incorporating darks, flats, and bias frames). These were then aligned with respect to a single "master" frame using PixInsight's dynamic alignment tool. Each night the sky quality was very variable - light pollution reflecting of various densities of fog caused problems calibrating the frames correctly. I used the Automatic Background Extraction and Auto Histogram tools in PixInsight to remove the LP gradients and to get a common mid-tone for all the frames. These were then all bought into Photoshop, aligned in layers, and the white and black points around the comet equalised with the master reference frame.

As it turned out, I could not use all the frames on the mosaic as Holmes did not traverse its own distance across the sky within 24 hours, but I was blessed with good skies and so had fairly good coverage.

In total, I took 2279 frames, each of 8 seconds duration. This gives a total "integration" time of 5 hours, 3 minutes, and 52 seconds. Bar far the longest exposure I've ever synthesised! What is really interesting is that I managed to
(just) capture down to magnitude 11.5 stars around Mel20 with just a 50mm lens and 8 second subs ... I would not have believed it possible, even without my light pollution!

All in all a rather enjoyable project :) Now ... what's next on the list ......

Tuesday, November 13, 2007

HCG-7

I have finally got around to processing part of the HGC7 set we received from the Faulkes team a while back. 2 sets of shots were taken to try to create a mosaic capturing the large angular size of HCG-7. This section shows HCG-7a (NGC192) and HCG-7d (NGC197), and the other section includes HCG-7b (NGC196), but we missed out on the face on spiral of HCG-7c (NGC201).





All the galaxies in this group are of similar magnitude and have been imaged before from Hubble, the NGC/IC project, and as part of the DSS plates. Yet again though, none of these images have captured the subtle detail we are able to get out of the Faulkes North CCD camera - even though the current camera is a lot less sensitive than the original CCD that was used for some of the earliest Hickson images we took. Never the less, it is fascinating to think that we may be the first people to actually see this detail within these galaxies.

Whilst Googling around for information on this Hickson object, I came across a rather useful Italian website on the Hickson Compact Galaxy groups here. Google will quite happily translate this page if Italian is not your forte! The sight contains links to the aforementioned images, as well as brightest component magnitudes - but these do not agree with other sources such as that of simbad (Note that Aladin records the galaxies by their NGC designation) I'm not sure who is right, but I think I'll go with Sinbad for now!

Processing of the image was performed using Iris, Pix Insight, and Photoshop from a set of 10 red and 10 green images (the 10 blue images were too noisy to use and hence why this one is not in colour).

Tuesday, September 04, 2007

Fine Summer Nights

I managed to sneak my ED80 on holiday with me to Cornwall for a week in August, and I was treated to a week of the clearest and darkest skies I've seen for a very, very long time.

We stayed in a converted barn out in the middle of nowhere on the top edge of a valley which gave an amazing uninterrupted 270 degree view south right down to the horizon. It was an astronomers dream.

Every night turned out to be a bit of a "star party" with the
(non astronomer) friends we were staying with. I had expected to be the only one outside after the initial "Oooh, a telescope - what can you see with that", but everyone was amazed at all the stars that we could see because of the dark skies.

On the first couple of nights we were treated to a bit of a meteor show with some very bright trails through Cygnus and down towards Sagittarius. We also watched the International Space Station fly overhead and I did a tour of Jupiter, Uranus, and Neptune. Not that there was much to see with the latter two planets, but the thought of the distances involved seemed to more than make up for that. Moving on to M31 in Andromeda, globular cluster M13 in Hercules, and M22, M8 (Lagoon), and M20 (Triffid) in Sagittarius gave everyone a one-stop-shop to the types of objects up in the sky.

After the others all went off to bed I had a chance to do a mix of imaging and visual observing - the results of that will come later (oh, where does the time go!). Using my Canon 10D, armed with a hair dryer to fend of the dew, I took some wide (28mm and 50mm) shots of Cygnus, Sagittarius, and Scutum. Clearly visible to the naked eye was the Cygnus Rift, Scutum star cloud, as well as all sorts of other lumps and bumps of stars along the Milky Way which stretched right down to the horizon under Sagittarius.

Later in the week I got organised early and took some shots of Jupiter with my ToUCam on the ED80 early in the evening whilst it was still high up (though it was easily visible well up to midnight). Unfortunately I did not have my barlow lens to hand, so all I could snap was a prime focus shot, but I'm very pleased with the details I was able to capture considering its low elevation. Processed in Registax, PixInsight, and Photoshop you can see the result below. I don't think I'll get another shot of Jupiter this year so I'm just going to have to just savour this shot for now:)



Sunday, June 17, 2007

HCG-51 Update

I got into contact with the British Astronomical Society about the mysterious "star" on HCG-51b ... had I just discovered a supernova or something exciting like that? Well, no. But that isn't too surprising really!

It turns out that the Aladin search plates that I (and others) were using did not go deep enough for finding stars this faint. To go this faint you need to use the SDSS SkyServer - something I was not aware of until now, but will certainly use again. A search on this returns a positive identification of a <20 magnitude star superimposed on the galaxy.

Better luck next time eh :)

Wednesday, April 18, 2007

HCG-51

HCG-51 is a small grouping of 7 galaxies, 5 of which are fainter than magnitude 14, and the other two just bright enough for William Herschel to come across back in the 1780's and get an NGC designation. Located around 4 degrees north east from Delta Leonis, the grouping nicely fits into the Faulkes's field of view.


Using the Aladin Sky Atlas I was able to identify more formal designations of the members, taking the names from the Uppsala General Catalogue (UGC), the Morphological Catalogue of Galaxies (MCG), and the (now superseded) LEDA catalogues. What I could not find was galaxy classifications for these objects.

The best current images of HCG-51 I found on the internet were taken as part of the Palomar Observatory Sky Survey (POSSII). These images just don't quite get to the resolution of this Faulkes image though, so maybe some of the structures are being seen here for the first time .... which is a rather nice though!

Members a, e, f, and g certainly seem to be various forms of elliptical galaxies, and b is certainly a barred spiral, but c and d are a bit more interesting. D, to me, seems like a face on spiral - only just visible in this image with its clockwise arms, and c could almost be construed as a mini Sombrero, viewed from slightly underneath, with its distinct dust lane across its central bulge.

There are a few other very faint galaxies in this image to the centre bottom. As with other Faulkes images, I have been unable to locate any database that can tell me what these objects are.

But, on a final intriguing note of interest, is the "star" on the face of HCG-51b. This is not on the Palomar plates , and is not a hot pixel as it tracks with the
R exposures across the frame, though it is not very visible on the V and B frames. Could it be a super nova or something similar? I don't know, but one can wish :) Maybe a follow-up observation is needed ...

Sunday, March 04, 2007

Hickson 44c

Hickson 44c is a 13th magnitude spiral galaxy about 70,000,000 light years away in the neck of Leo and is part of the gravitationally bound Hickson 44 cluster. Unfortunately the entire group (spanning around 15') cannot be captured on a single frame from the Faulkes telescope because of its size. HCG44d looks like it will be an interesting target when we return to image it later. As will HCG44a, which gave a rare birth to 2, almost simultaneous, super novae back in 2002 - SN 2002b0 in March, and SN2002cv in May - discovered by a group of Italian astronomers whilst observing SN 2002bo! Normally, astronomers expect one supernova per century in any given galaxy, so this was a rare event indeed.


Thursday, February 22, 2007

Hickson 40 - Faulkes Telescope North

Hickson 40 (also cataloged as ARP321) is a fairly bright compact group of galaxies 300 million light years away in Hydra. The brightest component (HCG40a) is around magnitude 12, and the faintest (HCG40e) around magnitude 17. Again, this group contains a nice mix of sprial and elliptical galaxies and was imaged by the 8.2m Subaru telecope and shown on APOD 8 years ago. Although we didn't get as deeper image as the Subaru, it does have 16 times the light gathering power! Still, you can easily disern the main spiral galaxies in the cluster.

This is the second image from the Faulkes Hickson Compact Galaxy set - please see the previous post below for more details about the Hickson catalog and Faulkes telescope in general.


3 sets of 120 second images were registered and stacked for each of the RGB channels. A pseudo luminance image was created by stacking the calibrated RGB frames and then more agressively processed and recombined back into the final LRGB composite.

Wednesday, February 21, 2007

Hickson 37 - Faulkes North Telescope

In the '80's, Paul Hickson created a catalog of compact galaxy groupings that he used to study galactic evolution and gain the first evidence for that elusive material - dark matter. The Bristol Astronomical Society has been working with the Faulkes Telescope to image parts of the catalog in detail that only a research grade telescope and CCD camera can do justice.

This image is of Hickson 37 - a grouping of 5 galaxies (though a few more are visible on this image). I trawled the internet to try to find images of this grouping, but the best I found was from the Space Telescope Science Institute (STScI) Digital Sky Survey plates. A direct link can be followed here if the hyper link works, else can be searched for using its SIMBAD name of HCG37, and the POSS2/UKSTU Red plate here.

A set of 3 frames per channel (RGB) were taken, each of exposure 240 seconds, using the 2m F/10 Ritchey-Chretien Faulkes North telescope situated atop Haleakala on the H
awaiian island of Maui. These were then registered and processed with the fabulous free Iris image processing application, and PixInsight.


You can see a nice cross section of different types of galaxies here - from elliptical to spiral to barred spirals. I'm rather fond of the side-on sprial HCG37b - the dust lanes are quite exquisite in their detail! The biggest elliptical, HCG37a, is also known as NGC2783 and has a magnitude of around 13. This gives an insight in not only the faintness of the Hickson cluster members, but also the sensitivity the Faulkes Telescope CCDs.

The classification of the galaxies in the cluster for the annotation were located here, although there is no mention of the 2 small, almost perpendicular galaxies just to the side of HCG37a - incidentally they are only just visible on the DSS plates. I tried to ID these using various star charts to find their designations and magnitudes, but I could not find any mention of them. If anyone can shed some light on them, please do!


Constellation Tour

I've been having fun with my Canon 10D DSLR lately, using just a simple tripod and 28mm SLR lens (which is probably more like 40mm as it's a lens from an old 35mm camera). With this set up, one can easily take exposures of 15-30 seconds without noticeable trailing, only depending on how close to the celestial equator the target is. I rather like this sort of wide field imaging as not only is it really easy, but it also really helps you find your way around the sky during the different seasons of the year - a must when you start looking for more specific objects and comets.

The first target was good old Orion, taken from my back yard in the centre of the city - so plenty of light pollution to combat! The results were quite surprising - especially when compared to the images I took at my Dark Site ... but i'll get onto that in a minute! This was a stack of 15 second images that needed heavy gradient removal to get a flat background due to sodium light below, and near full moon glow from the left.





Compare this to an image taken from my dark site below - there's not a lot of difference, but I put that down to the full moon present when they were taken. It might have helped being 2am on a very cold night ... it's amazing how your patience can be so tested at late hours and cold temperatures!


Next up was the home of a good few Messier objects - Auriga. Whilst easily discerned with the naked eye and bright moon light, once captured and processed it becomes another story! The image has a myriad of stars that can be quite confusing at first, and was the reason I decided to place annotated images next to the originals. Personally, I find doing this helps me learn my around both constellations and the night sky itself.



Just around the corner from Auriga is the constellation of Perseus. This contains one of my favorite binocular objects in this part of the sky - MEL 20 (Cr39) - a wonderful open cluster containing a good few dozen stars. Situated in the centre-top of the main body of Perseus, it fills the view of 10x50's perfectly. It's a real jewel so be sure to check it out!



Last stop on the tour is Taurus, the Bull. With the wide field of view provided by the 10D and 28(40)mm lens, this also incorporates the famous Pleiades - M45. Again, the rich field of stars on a photograph can hide the shape on Taurus, but in this case the bright red "eye" of the bull, Aldebaran, is quite apparent.



Hopefully I've inspired you to go out and have a go with your own digital camera. All you need is to be able to manually set the exposure to as long as possible, and set the focus to infinity. If you can't do the latter, try pointing the camera towards a distant object to get it to focus. Keeping the half-depressed shutter button down, turn the camera back to the area of sky you wish to take and press down fully. Use a hat or similar to cover the lens as you press to stop capturing camera shake as you let go of the button if you don't have a timer on the camera.

Go on ... have a go :)