M101 - The Pinwheel in UMa

[coatesg]

I finally got round to finishing off processing a load of data I took on 18th/19th April (!) - M101 the target here.

Details:

WO FLT110 @ f7 on Losmandy Titan, ST2000XM cooled to -20C

L: 4.5hrs (1x1)
R: 70min (2x2 binned)
G: 48min (2x2 binned)
B: 48min (2x2 binned)

It's not perfect - the flats didn't quite remove everything, and there's a couple of low colour gradients I've since spotted that need ironing out, but they are barely noticable, and depend strongly on how well your monitor is calibrated. I'm fairly pleased with the b/w version though - as well as NGC5477, MCG+09-23-25 to the left (west), there's a lot of faint background stuff in there (loading the plate solved version into Aladin is always fun - and then you realise that the "bright stars" you're struggling to contain are actually Mag 12+...) . 

Thanks for looking!

[xtreemchaos]

very nice images mate,great colour and detail. thanks for sharing. charl.

[AndyUK]

Very nice indeed, Graeme... but if I might be so bold, I reckon running an HLVG filter on it would help get rid of a fair deal of that gradient

[coatesg]

Think you're right Andy - It didn't really show on my home monitor, but I noticed it on this laptop as soon as I uploaded the files for the post. Theres a green gradient from bottom right, and there's a slight magenta hue in the top left I need to sort out... Image fiddling never ends does it? ;-)

Cheers

[Stub Mandrel]

Nice, I hope I can get detail like that one day.

But how did you manage to take a photo of it from the far side?

Or perhaps it's just a mirror image...

[coatesg]

Nice, I hope I can get detail like that one day.

But how did you manage to take a photo of it from the far side?

Or perhaps it's just a mirror image...

Ha! It's flipped top-to-bottom - FITS Liberator does this to FITS files for me for some reason (is this common to anyone else?). I haven't flipped it back.... (Could have claimed I have a back illuminated CCD, but that would be a fib ;-)

North is Up, East is Right. In the above - I'll fix it when I do the gradients!

[Stub Mandrel]

Ha! It's flipped top-to-bottom - FITS Liberator does this to FITS files for me for some reason (is this common to anyone else?). I haven't flipped it back.... (Could have claimed I have a back illuminated CCD, but that would be a fib ;-)

North is Up, East is Right. In the above - I'll fix it when I do the gradients!

Damn, for a minute I thought you had got hold of the infinite improbability drive :-)

[coatesg]

Re-did them again on a decent monitor...! Think I've done the best I can now on the gradients and getting the background levels correct... (and flipped them to avoid the parity issue above).

[ollypenrice]

Much better without the gradients but be careful not to black clip the faint data.

This is a darned good image and from your location I doubt you have an ultra dark sky. You have a deep image here. Chapeau, as they say round here! This is good stuff.

Olly

[coatesg]

Much better without the gradients but be careful not to black clip the faint data.

This is a darned good image and from your location I doubt you have an ultra dark sky. You have a deep image here. Chapeau, as they say round here! This is good stuff.

Olly

Thanks Olly,

Have struggled a lot with the background on this - the flats were the biggest issue here as I can see artifacts that weren't removed by flats as I'd otherwise expected (though not 100% as to why it didn't quite work out here).

We're not too bad in terms of skies here - there are few lights within half mile, though it's all relative in terms of UK sky quality - Oxford, Witney and Brize Norton airbase all surround...

Cheers

Graeme

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