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darditti

M42 ZS66 semi-narrowband

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I take an image of M42 every year, using a different combination of equipment each time, and the results are different every time. It is always interesting, no matter how many other images have been taken of this object. Here is this year's, taken entirely on the evening of 2010 January 16. I am dedicating this image to the memory of Andrew Ainslie Common, on the subject of whom I gave a recent lecture to the BAA. He took the first really good image of M42 in 1883, from a location about 5 miles from my house. He used a 36-inch (914mm) telescope, but I used one 14 times smaller on this occasion, with 1/196th the light-grasp.

This image was taken through 3 filters: a Baader broad H-alpha filter (35nm passband), an Orion Skyglow filter (a greenish filter admitting mostly OIII light), and a Baader H-beta filter (8.5nm passband). These were mapped to RGB to give an approximate "true" colour rendition. So it is what I might call a semi-narrowband image.

The red channel consists of 6x5 minute exposures combined with 6x2 minute exposures and 6x1 minute exposures. The green channel consists of 6x2 minute exposures combined with 6x1 minute exposures. The B channel consists of 6x5 minute exposures. The purpose of combining the shorter with the longer exposures was to increase the detail retained in the bright core. Total exposure was 96 minutes. Initial stacking was done with Deep Sky Stacker, and subsequent processing with Photoshop CS4. Only levels and curves adjustments were applied.

Nine dark frames of various exposures were also used, plus 16 flat frames and 16 dark flat frames.

The tracking was using an Astro-Physics 1200GTO mount unguided.

David

M42-2010-12-16-66dedMR-DLA.jpg

(Click to enlarge)

M42 2010 December 16. William Optics ZS66, 0.8x focal reducer, Artemis 285 camera, Baader 35nm H alpha, Orion Skyglow, and Baader 8.5nm H beta filters

Exposures: 6x5 mins + 6x2 mins + 6x1 mins H apha, mapped to R, 6x2 mins + 6x1 mins Skyglow mapped to G, 6x5 mins H beta mapped to B, 9 darks, 16 flats, 16 flat darks. N up.

David Arditti, Stag Lane Observatory, Edgware, Middlesex, UK

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Interesting project David, and an interesting story behind the dedication too :)

Nice to see you posting images again btw, much appreciated.

Cheers

Tim

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Excellent result from the little zs66 David.. It's done justice to the Monarch of nebulae. My term for M42 I'm afraid.

A very nice Tribute too. It's great when the Giants who's shoulders we stand on, are remembered.

Those words are not mine, and I'm darned if I remember who did say them first.

Ron.

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"If I have seen further it is only by standing on the shoulders of giants" – Isaac Newton in a letter to Robert Hooke

Thanks all.

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Very nice result David!

Just making a comparison between Andrew Ainslie Common's image and yours, I think it is really interesting to see how

much technology has advanced and become available to the masses very rapidly. A nice tribute to the pioneers too!

Jordan

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Yes, though, in fact, I have a scan of a better print from Common's original negative than the one reproduced on Wikipedia. I can't put it on a website for copyright reasons, but I included it in my talk. When I showed it, it produced a gasp of amazement from the audience.

David

Edited by darditti

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Surely the copyright has expired now? I'd be very keen to see a better version that the wiki one :)

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A delightfully atmospheric and 'retro' image, David, as befits the dedication. With a single exposure time the filter combination has controlled the dynamic range far better than RGB.

A propos the shoulders of giants, before admiring a moment of apparent humility on Newton's part we should remember that Hooke was dwarfish and deformed, Newton's point, therefore, being that he acknowledged no debt to Hooke.

Ron's point was in a more generous spirit and I entirely agree. I often think of E.E. Barnard, for instance, when taking my own humble pictures.

Olly

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