Christmas Comet

December 27, 2014 by grahamrob in General Astronomy, Other, Solar system and tagged Comet | 1 Comment

C/2014 Q2 Comet Lovejoy is a long-period comet, only recently discovered by Terry Lovejoy in August; it is the fifth comet discovered by Terry. By December 2014 the comet had brightened to a magnitude of +7.4 and by mid-December had become visible to the naked eye with dark skies. This weekend on 28th and 29th December, the comet will pass 1/3° from the globular cluster M79, subsequently brightening in January to a magnitude of +4.0 to +5.0, as it moves west of Orion and onwards towards Aries and Triangulum, thereby becoming one of the brightest comets for years. On 7th January 2015 the comet will be at its closest to Earth at a distance of 43,600,000 miles.

C/2014 Q2 Comet Lovejoy Projected Track

Before entering the planetary region in the 1950s epoch, C/2014 Q2 had an orbital period of 11,500 years, after leaving the planetary region in the 2050 epoch it will have an orbital period of about 8,000 years. Thus, unbeknownst to me, it has been with me since I was born and will remain with me for the rest of my life!

I have not seen the comet yet but have just been sent an excellent picture just taken from Joan’s Tacande Observatory in La Palma , which I visited earlier this year. Of course, I’ll be looking out for C/2014 Q2 at the weekend and hope to follow its journey during the next few weeks and beyond. Well done Terry and thanks again Joan.

C/2014 Q2 Comet Lovejoy R120 Canon 350D | 180 secs @ ISO 400 | taken by Joan Genebriera at Tacande Observatory, La Palma, 23rd December 2014

C/2014 Q2 Comet Lovejoy
R120 + Canon 350D | 180 secs @ ISO 400 | Taken by Joan Genebriera at Tacande Observatory in La Palma, 23rd December 2014

It’s Christmas Time

December 24, 2014 by grahamrob in Deep Sky Objects and tagged DSO Imaging, Nebulae | 4 Comments

Being that time of the year and with my new interest in astronomy, the possibility of imaging the Christmas Star seemed like a good idea. However, looking into the matter it becomes apparent that there is much controversy over what the actual object might have been: a star, a supernova, a shooting star (meteor), Venus or Jupiter etc. Furthermore, it even seems that we don’t know for sure when Jesus was born. Apparently due to an error by a Church cleric hundreds of years later, it is thought the birth could be up to 4 years later than believed and almost certainly was not on December 25^th! This is all news to me and makes a timely image of the night sky difficult but then, on a rare clear night last Friday, I turned the telescope and camera on NGC 2264 in the constellation Monoceros, or the Unicorn, itself within the Orion arm of the Milky Way Galaxy. Situated on the Celestial Equator to the east of Orion and above Canis Major, Monoceros is something of a new name to me. Considered a ‘modern’ constellation, since being discovered more recently than many others in the 17^th Century, it turns out to be abundant with many exciting objects. But at this time of the year it has to be NGC 2264 or the Christmas Tree Cluster which is most worthy of attention.

At first, whilst the images from the camera looked very promising and the ‘tree’ showed up well, it’s equally interesting partners were nowhere to be seen – notably the Cone Nebula and Fox Fur Nebula. Notwithstanding, following more aggressive processing adjustments they appeared, albeit smaller in my image than expected and very noisy. Technically, lessons arise from this: (i) whilst the William Optics GT81 is a great telescope with outstanding optics, it is a small telescope, and only the very largest features will fill the image (ii) in this case and probably more importantly, in order to achieve an acceptable signal to noise ratio, only longer exposures will work – I am currently working on this, with the goal of starting to autoguide as soon as possible in the New Year. Furthermore, the nebulosity is mostly Hydrogen Alpha (Ha) emission type, which my unmodded sensor therefore responds to poorly due to its inbuilt UV/IR filter; something else to deal with in the future.

Notwithstanding, I am still pleased with the result which in the end does show most of the main features, albeit with plenty of room for improvement; I also know how but getting there will not be easy. For obvious reasons the star of the show (no pun intended) is the Christmas Tree Cluster. The bright star at the bottom of the picture is Monocerotis 15 or S Monocerotis, which forms the tree’s ‘pot’ and is a quadruple system of four brilliant white stars. A little confusing, the view we get from earth of the ‘tree’ is upside down, so the following image has been inverted and is before post-processing, so as to make the stars that form the outline of the tree more clear.

NGC 2264 Christmas Tree Cluster - inverted to better show the 'tree' shape i.e the top is south

NGC 2264 Christmas Tree Cluster, before post-processing and inverted to show the ‘tree’ shape i.e the top is south. The large, bright star, 15 Moncerotis, marks the base of the ‘tree’.

However, the Christmas Tree Cluster is only part of NGC 2264’s glorious nature, most notable of which is probably the Cone Nebula. Located below (south) of the Christmas Tree, the Cone Nebula is a towering, triangular shaped column of cold, dark molecular hydrogen gas and dust, which appears to be flowing out from the young stars located close to the top of the cone. Some 2,200 light-years distant from Earth and 900 light-years further than the Orion Nebula, the Cone is quite small in the original picture but is in fact 60 arc seconds or 40 light-years in size!

NGC 2264, actual orientation: Cone Nebula at the bottom, Monocerotis 15 at the top with the Fox Fur Nebula to right but not clear, outline of the main stars and numbla defines the (invered) Chriostmas Tree Cluster WO G T81, Canon 700D + FF | 30 x 120 secs + darks/bias/flats @ ISO 800

NGC 2264 (actual orientation): Cone Nebula at the bottom, Monocerotis 15 now at the top, with the Fox Fur Nebula to the right but not visible. The outline of the main stars and associated nebulosity defines the (upside down) Christmas Tree Cluster – 15 Monocerotis is now at the top.
WO G T81, Canon 700D + FF | 30 x 120 secs + darks/bias/flats @ ISO 800

Map of Cone Nebula

Also included in the NGC 2264 region is the wonderfully named Fox Fur Nebula, so called as it is said to look like the head of a stole made from red fox fur. Combined with the aforementioned Ha light issue, my equipment cannot do this feature justice at the moment but, using an image from elsewhere, when viewed close-up (and you get your eye in) it is a very convincing feature.

Fox Fur Nebula

In addition to the above, NGC 2261 or Hubble’s Variable Nebula is worthy of mention. Located nearby to NGC 2264 this fan shaped nebula is illuminated by the star R Moncerotis.

NGC 2264 Christmas Tree Nebula shown by red box. Lower arrow points to the Cone Nebula, upper arrow indicates location of the Fox Fur Nebula. NGC 2261 Hubble’s Variable Nebula shown by red hexagon.

NGC 2261 Hubble’s Variable Nebula, illuminated by R Monocerotis star

Altogether there are more than seven nebulae to be found in this region of the sky, which has turned out to be something of a pleasant surprise to me and will be revisiting once I can achieve longer exposures and deal with Ha light better. The constellation of Monoceros is also itself something of a surprise, with the prospect of some other great images that deserve further attention in the New Year – can’t wait for Christmas to finish.

Sunset at Fairvale Observatory on the evening before the Winter Solstice

Sunset later the same day at Fairvale Observatory, the evening before the Winter Solstice

Lace up the Nikes

December 2, 2014 by grahamrob in Deep Sky Objects and tagged DSO, DSO Imaging, Orion | 2 Comments

There is no doubt in my mind that the Orion Constellation is the most spectacular of the year and right now comes into imaging view at Fairvale Observatory at about 11pm, about the same time the waxing Moon disappears over the horizon; for once the timing is perfect. So before the presence of the Full Moon later this week rules out astrophotography, last Saturday evening provided an excellent opportunity.

The more I look at the Orion Constellation the more there is to see and image, as well as some other attractive objects that will be around until at least the New Year and in some cases well beyond. One lesson I have learned early on with astrophotography is the need for good planning: what’s around to image? when is it in the best location i.e. near the Meridian? what equipment is needed and is it working? set it up in good time and ensure good alignment. Given the aforementioned favourable conditions and the arrival of Orion, my list of objects this month is considerable:

Early evening: M32 Andromeda Galaxy & NGC 1499 California Nebula.

Late evening / midnight: Orion Constellation – NGC 2024 Flame Nebula, IC 434 Horsehead Nebula, M42 & M 43 Great Orion Nebula, NGC 1977 Nebula, NGC 1981 Emission Nebula, NGC 1909 Witch Head Nebula, SH 2-276 Barnards Loop, SH 2-264 Angelfish Nebula, M78 reflection nebula and more. Other – M1 Crab Nebula, Hyades (Taurus), M77 barred spiral galaxy and Jupiter, which together with its four moons is also looking very nice after 1 a.m. at the moment.

With such an array of possibilities it can be difficult to know where to start but having recently achieved good images of the Great Orion Nebula and the Flame and Horsehead Nebulae, the next target was an easy choice – it had to be NGC 1977, which with the William Optics GT81 field-of-view also takes in NGC 1981 and M42, three for the price of one!

Orions Sword. Top to bottom: NGC 1981 Open Star Cluster, NGC 1973/75/77 Nebulae, M42 & M43 Great Orion Nebula & the binary star Hatsya. WO GT81, Canon 700D + FF | 30 x 120 secs + darks/bias/flats @ ISO 800

Orion’s Sword. Top to bottom: NGC 1981 Open Star Cluster, NGC 1973/75/77 Nebulae, M42 & M43 Great Orion Nebula & the binary star Hatysa.
WO GT81, Canon 700D + FF | 30 x 120 secs + darks/bias/flats @ ISO 800

There is so much going on in this photograph that merits attention. The view encapsulates all the major components that form Orion’s Sword, notably from top to bottom: the open star cluster NGC 1981, the star Theta Orionis C in the Trapezium cluster – itself within M42 and the star Hatysa (Iota Orionis), which forms the tip of the sword. Obviously M42, The Great Orion Nebula dominates the scene but two other major features are worthy of attention too.

Orion’s Sword – detail

The aforementioned NGC 1981 is an open cluster of about 20 stars located 40 light years closer to Earth than M42. But it is what’s between M42 and NGC 1981 that was my main target this time: the reflection nebulae of NGC 1977 and related NGC 1973 & 1975, AKA the Running Man Nebula, so named because it looks like a running man! The three nebulae are illuminated by the blue light shining from young stars that are forming within each area of nebulosity, which are separated by dark zones of interstellar dust in the form of a man running – not unlike Eadweard Muybridge’s pioneering photographic images of motion taken at the end of the 19^th Century, I am sure he would have appreciated the analogy.

NGC 1973/75/77 The Running Man Nebula (rotated – North is left)

Eadweard Muybridge’s photographic studies of a running man, late-19th Century

The Horse & Flame

November 26, 2014 by grahamrob in AstroBin, Deep Sky Objects, Imaging and tagged DSO Imaging, Nebulae, Orion | 2 Comments

With the full moon early in the month and some truly awful weather, I have been unable to get out at Fairvale Observatory since October 31^st! Notwithstanding , this has been an opportunity to spend time learning more about the dark art of processing, which can sometimes be more important than image capture itself, so is hopefully time well spent. Apart from the usual assistance of Mr Google, I have purchased the excellent online ‘book’ of Jerry Lodriguss, Photoshop for Astrophotographers – which I am slowly working through, and watched the equally excellent YouTube tutorials by Doug German on the same matter. It is often said that a picture is worth a thousand words, and Doug’s tutorials are probably the easiest and most accessible way into the use of Photoshop for astrophotography – I also enjoy his dry sense of humour. Finally, I am currently trialling Russell Croman’s Gradient Exterminator, which is intended to remove the external light gradient that inevitably creeps into even the best of images; it’s early days but I think I like it – it’s tricky to use and Doug German’s video tutorial is very helpful in this regard too.

The extended absence of clear night skies for astronomy also benefits subsequent viewing as the sky has changed, in this case a lot. We have now moved on to winter skies, which are best exemplified by the constellation of Orion here in the northern hemisphere. I was initially successful in imaging the iconic Orion Nebula early in October but only by getting up very, very early. At Fairlvale Observatory it now comes into view at about 10pm and after 11pm can be imaged. With clear skies finally arriving last Sunday evening, albeit accompanied by very cold temperatures, I was finally able to get out again – this time to spend more time with Orion.

In my ignorance, what has surprised me about Orion is the extensive presence of spectacular nebulae throughout the constellation: M42 Orion Nebula, M43 De Mairan’s Nebula, NGC 1973/5/7 The Running Man nebula, M78 between Alnitak and Betelguese etc, etc. But, I had also somehow overlooked the ‘Horse & Flame’, located above the Orion Nebula nearby the lower end of Orion’s belt: Mintaka – Alnilam – Alnitak. In close proximity to Alnitak (a triple star), which with an apparent magnitude between +2.0 and +4.0 is a problem for imaging, the sky is full of spectacular nebulae – notably the Flame Nebula and the iconic Horsehead Nebula. Having latterly learnt of their presence in the same part of the sky, I had to try and image them.

The Horsehead Nebula is a cloud of interstellar dust and gas that, as a result of it’s density, appears dark against the surrounding red nebulous ‘curtains’. The resulting shape looks like, well a horse’s head and has therefore become an iconic and well known image. However, located on the other north-eastern side of Alnitak is perhaps the real star (no pun intended) of the show, the Flame Nebula – NGC 2024. A combination of dark gas and dust with glowing hydrogen gas, energised by ultraviolet light emitted from Alnitak. Such is the form of these materials that the resulting effect is that of a burning flame. I was therefore thrilled that after my enforced indoor sojourn to be able to capture the Horse and Flame (sounds like a pub I’d like to visit!) together in one beautiful picture.

The Horsehead and Flame Nebulae. The Horse is located directly below (south) the large bright star Altinak triple star which forms the eastern end of Orion's belt, about half way down the image, sticking its 'head' into the red curtain nebulosity. The Flame is just to the left (east) of Altinak. WO GT81, Canon 700D + FF | 28 x 90 secs + darks/bias/flats ISO 1,000 | Photoshop processed + Gradient Exterminator

The Horsehead and Flame Nebulae. The Horse is located directly below (south) the large bright Alnitak triple star which forms the eastern (left) end of Orion’s belt, about half way down the image, sticking its ‘head’ into the red curtain of nebulosity. The Flame is just to the left (east) of Alnitak.
WO GT81, Canon 700D + FF | 28 x 90 secs + darks/bias/flats ISO 1,600 | Photoshop processed + Gradient Exterminator

The Kiss

November 12, 2014 by grahamrob in Comments, Solar system | Leave a comment

The EU political project has not exactly been a roaring success but, in stark contrast, European science, engineering and technology is second to none and is still pushing the boundaries. In the spirit of centuries of unique European scientific developments, discoveries and vision that are responsible for much of the modern world now around us, today the European Space Agency (ESA http://www.esa.int/About_Us/Welcome_to_ESA/What_is_ESA ) successfully placed a lander on the comet 67P/Churyumov–Gerasimenko . As if the 10-year journey of over 6.5 billion kilometres wasn’t enough, the spacecraft Rosetta successfully delivered its passenger, the lander Philea, to its landing Site-J (now renamed Agilkia), on the surface of a comet moving at 40,000 mph through space http://www.livecometdata.com/comets/67p-churyumov-gerasimenko/ . Launched in 2004 its technology is by now well out of date – at the time the iPod had only just been launched – but the accomplishment is nonetheless fully 21^st Century. Science fiction today became science fact, even Major Tom would be impressed, certainly Captain Kirk (William Schatner) Tweeted his best wishes during the landing.

Looking back at the Rosetta spacecraft from the Lander Philea as is separated earlier today and began its 7-hour journey to the surface of the comet.

Looking back at the Rosetta spacecraft from the Lander Philea as it separated earlier today and began its 7-hour journey to the surface of the comet.

In the same spirit of watching the first lunar landing by Neil Armstrong and Buzz Aldrin in 1969, I have followed events live all day. The suspense was almost as exciting. The control room was in stark contrast to 1969 but with just laptops and flat screen terminals that could have come from PC-World; it looked like a low key trading room rather than the centre of a major scientific space adventure. Such is the distance from the comet to Earth that final confirmation of the landing took 28 minutes and 20 seconds to arrive, 28 minutes of suspense. Touchdown was at 16.02h GMT.

As Philea left for 67P/C-G it was described by ESA scientists to be moving in for the kiss, wow what a kiss. I can’t wait to see pictures from the comet’s surface and especially the science that will emerge later. Chapeau ESA!!

https://watchthisspaceman.wordpress.com/2014/11/03/rendezvous/

Philae on its descent from Rosetta to the surface of Comet 67P/Churyumov-Gerasimenko

The absence of light

November 10, 2014 by grahamrob in General Astronomy, Imaging, Viewing, Widefield Imaging | Leave a comment

“Light thinks it travels faster than anything but it is wrong. No matter how fast it travels, it finds that darkness has got there first, and is waiting for it.” Terry Pratchet, Reaper Man.

It may seem something of a contradiction that as astronomers we seek very dark places and skies in order to see light, light that may have travelled millions of light years to get here – light travels 6 trillion miles in one year. For human beings the perception of darkness differs with the mere absence of light, due to the effect of afterimages that are produced by the unstimulated (by light) part of the eye. Typically our eyes will take between 20 and 30 minutes to fully adjust to darkness, at which time the eye becomes between ten thousand and a million times more sensitive than in daylight.

Objectively the Bortle Dark-Sky Scale describes nine levels of darkness and thereby quantifies the astronomical observability of celestial objects and impact of light pollution http://en.wikipedia.org/wiki/Bortle . With digital photography the colour of a point is described on the camera’s sensor by three RGB (red, green, blue) values, each ranging from 0 to 255. Thus when each pixel is fully illuminated each colour component measures 255 or for an RGB image 255,255,255. Conversely when all values are zero or 00,00,00, it appears black. However, the night sky is not black but measures somewhere between 10 and 30 when imaged.

Night sky image (Eastern Veil) with dark point set at 0,0,0

Dark sky image (Eastern Veil) with dark point set at 20,20,20. This approximates best to the natural darkness of the night sky.

There are even four subdivisions to describe approaching darkness at night:

Civil Twilight: begins at sunset and ends when the sun is 6^obelow the horizon or more practically, it can be described as the period after sunset during which terrestrial objects can still be clearly distinguished. Normally the end of civil twilight is usually 20 to 30 minutes after actual sunset.

Nautical Twilight: describes the period when the sun is between 6^o and 12^o below the horizon, during this time it is now possible to take reliable star sightings at sea. It may more commonly be described as nightfall but it is still not strictly dark yet.

Astronomical Twilight: defined as the period when the sun is now between 12^o and 18^obelow the horizon. To the casual observer this may be considered dark but it’s not, only when Deep Sky Objects such as nebulae and galaxies can be viewed is it fully dark.

Therefore, only after this sequence is completed, which takes almost two hours after sunset here at Fairvale Observatory at this time of the year, does true astronomical night or darkness occur. The excellent FLO Clear Outside weather forecast website, which is linked on the front page of this website, shows the current timings for each of these periods every day along the top horizontal bar, just below the hourly sub-division headings.

Obviously this has a major bearing for astronomers and perhaps more so for astrophotography. So sensitive is the camera’s sensor that when using long exposures the cumulative light recorded, even in a dark-sky environment, may result in a bright image that will need to be corrected during processing. Notwithstanding, the holy grail for astronomers is a dark, clear sky and the biggest enemy (other than bad weather and cloudy skies) is light pollution, which is spreading inexorably across the globe.

At the beginning of this post is a NASA picture of the Earth at night, produced as a composite of image data from the Suomi National Polar-orbiting Partnership (NPP) satellite, taken in April and October 2012 over a period of 312 orbits. NPP passes over any given point on Earth’s surface twice every day, flying 824 kilometres (512 miles) above the surface in a polar orbit, circling the planet about 14 times a day http://earthobservatory.nasa.gov/Features/IntotheBlack/ . Away from the cities much of the other light from wildfires, fishing boats, gas flares or mining operation is also visible. Whilst undeniably a beautiful picture, for astronomers it highlights one of the major obstacles we are up against, light, or more accurately light present here on Earth. The night sky before the invention of the commercial light bulb by Tomas Edison in 1878 must have been a wonderful sight; I doubt that Messier (1730-1817) would have successfully catalogued all his 110 objects as easily with today’s skies.

The dark side of the world: city lights of Europe, Africa, Middle East & Central Asia

The dark side of the world, with light just over the western horizon.

Time Travel

November 5, 2014 by grahamrob in Deep Sky Objects, Imaging | 1 Comment

In my opinion the current 12^th Time Lord, Peter Capaldi, is one of the best doctors yet but it’s all just a good yarn, isn’t it? At the level of quantum physics the potential of time travel has recently been shown to be feasible and even the paradox of Schrödinger’s cat has now been experimentally demonstrated at a quantum level i.e. the same thing can exist in two places at the same time. Still, intuitively time travel seems unlikely but nevertheless last week I travelled back 400 million years without moving from Fairvale Observatory!

As a result of good viewing conditions and excellent alignment of the mount and telescope, I sought to capture light that left on its journey 300 million years ago. This time marks the end of the late Carboniferous era, taking its name from the period of worldwide formation of coal deposits, which resulted in the highest atmospheric oxygen levels the Earth has ever experienced (35%) and lead to an abundance of giant insects and amphibians as the first reptiles also appeared on Earth.

Widefield view of Stephan’s Quintet (red circle) and NGC7331 + Deer Lick Group (red box)
WO GT81, Canon 700D + FF | 20 x 120 secs + darks/bias/flats @ ISO 1,600

Located in the constellation of Pegasus, Stephan’s Quintet is a group of four galaxies whose respective gravities lock them in a cosmic dance with each other that will inevitably lead to their coalescence. The fifth and brightest member of the group, NGC 7320, is in fact just 40 million light years away but viewed from Earth appears to be spatially associated with the aforementioned group and thus makes up the fifth member of the quintet. Unfortunately my 80 mm telescope only shows a smudge of light from Stephan’s Quintet but it is light that has just arrived here at Fairvale Observatory after making a 300 million year journey, it is literally looking back in time. A more substantial Hubble image shows us exactly what was happening to these galaxies at that moment – it seems probable that they have by now come together but we’ll have to wait another 300 million years to see that.

Stephan’s Quintet taken by the Hubble telescope

Stephan's Quintet (bottom left) and NGC 7331 & Deer Lick Group (top left)

Stephan’s Quintet (bottom left) and NGC 7331 + Deer Lick Group (top right)

One advantage of the smaller 80mm William Optics refractor telescope is that its field of view is quite large and whilst seeking to capture Stephan’s Quintet, I also inadvertently managed to image another group of galaxies. In this case the dominant NGC 7331 galaxy with, apparently close-by but actually located up to ten times further away, the Deer Lick Group of galaxies. The magnificent NGC 7331 is a mere 50 million light years from Earth and is thought to be similar to our very own Milky Way. The Deer Lick Group (indicated by four red arrows in the main picture above) is however some 400 million light years* away – thus corresponding to the mid-Devonian period or the Age of Fishes; named after the red rocks first identified in Devon, UK and particularly known for its plethora of fish that developed at this time. I am quite sure that even The Doctor would be impressed by the time travelled by the light from these objects as it arrives here on Earth after such a long journey and provides us with a glimpse of the past, today.

NGC 7331 spiral galaxy (foreground) and Deer Lick Group above (see main anotated picture for detailed location). Light form the Deer Lick Group of galaxies is 400 million years old.

NGC 7331 spiral galaxy (foreground) and Deer Lick Group above (see main anotated picture for detailed location). Light from the Deer Lick Group of galaxies is over 400 million years old.

* For the record, light travels 670 million miles in one hour or 6 trillion miles in one year.

Rendezvous

November 3, 2014 by grahamrob in General Astronomy, Other and tagged Solar system | 2 Comments

At first this picture looks like something taken whilst walking in the Alps but, look again. It is a composite photograph taken on 28^th October by the Rosetta space probe, currently orbiting the 67P/Churyumov-Gerasimenko comet, approximately 7.7 km from the surface. I must admit I had been somewhat doubtful about the nature and chance of success of this mission but there’s no denying the science and technology is amazing, almost, but not quite, as exciting as the first Moon landing on 29^th July 1969.

The Rosetta probe was launched on 2^nd March 2004 and has since taken a circuitous route through deep space to eventually rendezvous with the comet in August this year. Initially approaching the comet at a maximum relative speed of 19,000 mph, the probe was put into orbit around the comet on 10th September, since when it has been mapping the comet’s surface and sending back some truly amazing photographs. This link provides real time tracking data from the probe, which locked together with the comet is currently travelling at 40,000 mph relative to the Sun. http://www.livecometdata.com/comets/67p-churyumov-gerasimenko/

Even now it sounds like science fiction and the best is yet to come. In nine days, on 12^th November, Rosetta is scheduled to send a lander to the comet’s surface. After attaching itself to the comet, a scientific mission will be undertaken by the lander in order to study its nature, origin and possible implications for life on Earth itself. Wow, can’t wait!!!

http://www.esa.int/Our_Activities/Space_Science/Rosetta/Europe_s_comet_chaser

Taken on 7th October, Rosetta takes a 'selfie' whist imaging the comet 16 km away.

7th October: Rosetta takes a ‘selfie’ whilst imaging the comet 16 km away.

The Bat

October 29, 2014 by grahamrob in Deep Sky Objects and tagged DSO Imaging, Nebulae | 1 Comment

It’s Halloween time of the year and I don’t like it. My problem is that in the UK this used to be a minor event, treated as a bit of fun for some and ignored by most. However, it’s been given the North American makeover and pumped up as a big deal, mainly on commercial grounds. Grrrrr!

Less seasonable has been the weather, which thankfully continues to be warm and sunny with occasional clear night skies. Hooray! A great combination enhanced further by the appearance of winter astronomy objects and since last weekend’s change of clocks 1-hour backwards, darkness from early evening. What’s not to like for the astronomer? Starting at 6 pm I was therefore able to spend more than 7 hours on Monday night imaging a procession of DSOs as they approached and passed the meridian. Moreover, I achieved almost perfect alignment and for the first time was able to obtain good exposures of between 120 and 180 seconds; had I tried I suspect even longer periods could have been achieved.

First off the rank was the Veil Nebula, part of the even larger Cygnus Loop, a massive supernova remnant. Located about 1,470 light years away and between 5,000 and 8,000 years old, much of this this emission nebula is not in the visible spectrum and what is is feint and difficult to image. I have already obtained a good photograph of the Western Veil of the nebula, also known as NGC 6960 or the Witch’s Broom https://watchthisspaceman.wordpress.com/2014/10/04/the-witchs-broom/ . Now with such good conditions and my best ever alignment, I decided to turn my attention to the Eastern Limb, or NGC 6992 and NGC 6995.

Cygnus Loop (Veil Nebula) in untraviolet light. Image area of the Western Veil highlighted by red box.

Cygnus Loop (Veil Nebula) in untraviolet light. Image area of the Eastern Veil highlighted by red box.

Using the new CLS light pollution filter and 30 x 120 second exposures, the resulting image from the camera immediately showed the full extent of this magnificent object, even before processing. Post processing the feature really comes to life, with large billowing waves of nebulous ionized gas and interstellar dust. The brighter, right-hand side (northern) of NGC 6992 trails off to the left (southerly) section of NGC 6995, also known as the Bat Nebula – well it is Halloween!

Eastern Veil Nebula – NGC 6992 (right) & NGC 6995 (left).
WO GT81 + Canon 700D & FF | 29 x 120 secs + darks/bias/flats @ ISO 1,600

NGC 6995 AKA The Bat Nebula (look carefully and you’ll see him!)

The Pinwheel

October 26, 2014 by grahamrob in Uncategorized | Leave a comment

Just under two weeks until Guy Fawkes Night, which commemorates Guido Fawkes failed attempt to blow up Westminster Palace (The Houses of Parliament) on 5^th November 1605 – a very British (English) event. In its own way the Universe has a myriad of its own fireworks and it therefore seemed a fitting moment to attempt an image of one last week, which given their spectacular form and similarity to the popular Catherine wheel, AKA a Pinwheel firework, had to be a spiral galaxy.

The firework is named in commemoration of a Catholic martyr and is worth describing here before returning to matters of astronomy, simply because of it’s graphic nature. Catherine of Alexandria lived during the fourth century A.D. but in a male dominated society, was unusually well educated and successfully converted many highly placed individuals to Catholicism. As a result, she was condemned to “breaking the wheel”, which involved having one’s limbs broken and threaded through an abundantly spiked wheel. The victim would succumb to his or her injuries, but only after several days. However when Catherine touched the wheel it miraculously flew into pieces, so she was beheaded instead!

A human Catherine Wheel (Pinwheel)!

Having researched the current night sky using the Cartes du Ciel planetarium programme and taking account of the weather, it seemed feasible to image both Andromeda and M33 galaxies in a three hour period around midnight. However, despite my thorough preparations I was to succumb to the best laid plans of mice and men and a return to previous frustrations.

I have recently added a number of excellent widgets to the front page of WTSM: the current Moon phase, real-time world daylight map and Moon position, live sunspot activity and the excellent astronomy weather site Clear Outside, developed and maintained by First Light Optics. There are also other weather sites listed under the Favourites menu. All these indicated clear skies on Tuesday from 9pm and onwards throughout the night – so I planned to set up at 10pm and by 11pm, as Andromeda approached the Meridian would start imaging, followed by M33 shortly after midnight. Contrary to the forecasts, at 10pm the clouds rolled in and did not clear until well past 11pm. Next, whilst my initial polar alignment wasn’t too bad but on a second iteration it got worse and after altogether five separate x2-star and subsequent polar alignments was not much better. My new found skill had deserted me and by now it was past 1am – Andromeda had passed, so I just had to have a go at M33 before it too moved well past its optimal Meridian position.

For this session I decided to use my new CLS light pollution filter and subsequently tried to apply some of the processing advice gleaned from two excellent astrophotography books: Long Exposure Astrophotography by Allan Hall and Making Every Photon Count by Steve Richards. I bought both these books earlier in the year, read them cover to cover at the time and then hadn’t picked them up since, which was a mistake as they’re full of good advice and information relevant to my current issues and problems; they are now required bedtime reading.

The CLS filter works by removing the wavelengths associated with light pollution but, as a result, leaves a dominant blue hue to the camera’s image, making it is necessary to rebalance the colour afterwards during processing. A useful SGL blog points the way on how to do this by setting the Background Calibration (bottom left) in the Stacking Parameters ‘Light’ tab of Deep Sky Stacker (DSS) to RGB Channels. DSS then normalises all three colour channels to the same value during stacking, producing a natural dark rather than blue background http://stargazerslounge.com/topic/82975-astronomik-cls-clip-canon-7d-very-blue-images/ . The result is quite effective, though I am not completely sure that the process has not introduced a slight red shift which subsequently needed to be dealt with in Photoshop.

This time, on the Advice of Allan Hall, I also adopted a number of other settings using DSS:

RAW Process settings – (1) turn off all White Balance choices (2) set the Bayer matrix transformation to Adaptive Homogeneity-Directed (AHD) rather than Bilinear Transformation – changing the way the RGB Bayer weightings work (3) set the Black Point to zero.

Stacking Settings – this determines the type of stacking i.e. which algorithm is used to interpolate between one pixel and another. I have previously been using Average but this time, on the advice of Allan Hall, Steve Richards and others adopted either (1) Kappa-Sigma Clipping or (2) Auto Adaptive Weighted Average for each set of images, Lights, Darks, Bias & Flats. Some further experimentation of other settings in this area, such as Alignment, will probably be worthwhile at a later date.

M33 – initial RAW image using CLS filter

M33 – x20 90secs @ ISO 1,600, stacked with background calibration applied and Kappa- Sigma Clipping, pre-stretching and post processing

Finally, following further advice from the aforementioned books, Mrs G and other sources I am also starting to delve deeper into the dark art of post processing using Photoshop. The scope here to change images is almost endless and I am concerned about where reality stops and the software takes over, particularly with colour choices. Notwithstanding these concerns it is a great programme, almost indispensable (GIMP is also a good & free alternative which I subsequently use for JPEG compression), the main purpose of which is to stretch the image and thereby reveal information otherwise hidden in the data – the impact is incredible and totally transforms the image.

And so despite numerous setbacks and a very late night I finally arrived at an image of M33, AKA the Pinwheel or Triangulum Galaxy; confusingly M101 is also known as the Pinwheel Galaxy. A mere 3 million light years from Earth, it is one of the most distant objects that can be seen with the naked eye, though requires exceptional dark sky conditions, so unfortunately not much chance of seeing it on 5^th November from here. I’d like to think that I can do better once I can achieve longer exposures but for the moment it’s my first spiral galaxy.