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M51 (NGC 5194)

RobH

By RobH
in Imaging - Deep Sky

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RobH

RobH

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Hello all.

Here’s my latest bash at this wonderful springtime target.

The surrounding very faint spiral arms are starting to show, but even with almost 14 hours of luminance time, it needs more to enable them to be brought out properly without the image ending up too noisy, so this will be added to next year.

I used 110 minutes worth of binned Ha data from last year added to the red channel, but will be shooting this again in unbinned mode as the lack of resolution compared to the rest of the data caused a few processing issues.

Here’s some background info…..

M51 was discovered by Charles Messier in 1774.

The spiral is actually closer to us than the smaller galaxy, NGC 5195 but they appear to have interacted in the past, when the smaller galaxy passed through M51 about 500 million years ago.At that time, it came from behind M51 and then about 50-100 million years ago passed back through the disc to its position now, which is just behind the main galaxy.

This was the galaxy that in 1845, Lord Rosse first saw spiral structure in galaxies, using his 72 inch 'Leviathan', then the largest telescope in the world.

At the time, it wasn't known that these were separate galaxies, and the so called 'spiral nebulae' were thought to be part of the Milky Way.

Full image here.....

pic and description page

Imaged in April 2010 from Dorset UK.

TMB 152 @ F8, Atik 16HR. Luminance. 10 x 10 minutes, 49 x 15 minutes

Red. 21 x 10 minutes

Green. 18 x 10 minutes

Blue. 23 x 10 minutes

Total imaging time. 24 hrs 15 minutes.

Cheers

Rob

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RobH

RobH

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Thanks all. :)

My original plan with this image was to combine the luminance data with last years data, which was another 5 hours worth in mainly 5 and 6 minute subs.

While the image that resulted was very noise free, the end result didn't go as deep as this one so I stuck to this years L data only.

On last years image, I used binned colour subs, but have now stopped doing this and shoot all of my colour data at full resolution and find that this gives a better image, although it means that my sub times for RGB are considerably higher.

Mark....I haven't had much chance to use the dob, being away at work, but did have it out for a night while I was imaging this, and thoroughly enjoyed it.

AK....just pop over at Salisbury and ask away!!

Cheers

Rob

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ollypenrice

ollypenrice

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Rob, that's mighty. It's all good but my favourite aspect (so far) is the halo in which all sorts of dynamic movements seem to be happening. Thrilling stuff.

I agree on binned colour if the object is very detailed with changes in colour over short spaces, as in the spiral arms here or in globulars. Worth going the extra mile.

Olly

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RobH

RobH

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Thanks Olly.

The halo is why I'll be adding to this next year, and will probably go for a lot of 20-30 minute subs as the really faint outer arms would cover this FOV and it'd be nice to catch them.

Cheers

Rob

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RobH

RobH

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Thanks again folks :)

Simon, webcam imaging is really best for planets and the moon, but it's worth trying on bright targets like M57, M27 and M42.

Michael....there really is no substitute for lots of scope time when imaging....it can get really dull when the weather means you're on the same target for a month though :rolleyes:

Cheers

Rob

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