Castle Point Astronomy Club
Dark Nebulae by Pete Carson
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Dark Nebulae by Pete Carson
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Imaged 2010 Sept 12th at the Kelling Heath Star Party, Norfolk, UK.

Televue TVNP101 100mm APO refractor 540mm fl.

Starlight Lodestar autoguider on G11 Mount. SBig ST8300M CCD camera. Images acquired in Maxim DL Pro 5. True Tech RGB colour filters. LRGB image L 60 mins 1x1, R 20 mins 2x2 G 20 mins 2x2, B 20 mins 2x2, Two hours total exposure. All sub exposures 300 seconds at -25 deg C.

Peter says; "The sky was sometimes hazy with occasional passing cloud."

You can see more of Peter Carson's photographs on his website by going to our Links page.

Stars, planets, galaxies, bright nebulae! The heavens above abound with bright, shiny things, but not everything up there is as bright and shiny as others and this wonderful photograph illustrates the point well. The left centre is dominated by patches where there is a dearth of stars, with another such patch to the upper right. These are of course molecular clouds – huge clouds of dust laden gas through which the light of the myriad stars that lie beyond cannot penetrate.

There is an interesting history on the road to learning the true nature of these dark and apparently empty regions; a history in which the celebrated American astronomer Edward Emerson Barnard (1857 – 1923) played an important part. During the last half of the nineteenth century there was much debate and conjecture as to the nature of these "voids" as they were often called, but it was widely held that they were just that – voids within the Milky Way; regions of emptiness in which there were no stars. Furthermore, it was assumed that where these voids extended all the way along our line of sight, right out to the boundary of the Milky Way, we were simply looking through and out of the Milky Way into an infinity of emptiness beyond. One has to remember that in those days it was not realised that other galaxies existed way outside the Milky Way. It was believed that everything that could be seen was part and parcel of the Milky Way and that beyond lay nothing at all.

Barnard spent a great deal of his career studying the considerable number of these dark nebulae in an attempt to ascertain whether they really were voids and during the course of this work he compiled a catalogue of no less than 342 of them. Peter has captured four examples here; B169, B170, B171 and B368 in Cepheus, but Barnard captured many, many more which can all be seen in his Photographic Atlas of Selected Regions of the Milky Way, the plates from which can be seen by following this link http://www.library.gatech.edu/search/digital_collections/barnard/index.html

Barnard’s photographs are truly amazing, but there can be little doubt that Barnard himself would have been utterly amazed by Peter’s photograph. Firstly, we can be pretty sure that Barnard would have loved to have been able to capture the colour in the stars. Secondly, and with the greatest respect to Peter, who uses a considerable amount of skill and exercises very great care taking his photographs, Barnard would have been utterly amazed at the comparative ease with which a photograph like the one above can be taken by modern amateur astronomers. It must be remembered that Barnard was using painfully slow photographic emulsions and had no such thing as an auto guider. Hence, he had to sit with his eye glued to the eyepiece throughout the exposure, constantly making tiny corrections to the telescope so as to ensure pin sharp images. The term "eye glued to the eyepiece" can be taken literally in his case, for there was one occasion when he came to the end of an exposure that had lasted for many hours, as they often did, that as he drew his head back from the eyepiece, he tore a piece of flesh from the side of his nose. Over the hours his nose had become frozen to the barrel of the eyepiece!


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