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