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.

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.