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The Rosette Nebula in Ha

MikeWilson

By MikeWilson
in Imaging - Deep Sky

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MikeWilson

MikeWilson

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Evenin' all,

I've been challenged by AndyUK to push my exposure times to a new personal record - 20 minutes!

I took 8 x 20 minutes, one was ruined (mount reached meridian) and so that left me with 7 frames that I'm pretty happy with! However I didn't have any matching 20 minute darks :)

Here it is:

6484695577_2997a6e8db_z.jpg

The Rosette Nebula in Ha by MikeWPhotos, on Flickr

Much better than my first attempt earlier this Spring, don't you think?

I also caught a glimpse of a mysterious visiting red dot near Leo. I think it's Mars - I can't wait to get a telescope on that one!

Good star hunting :(

Mike

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MikeWilson

MikeWilson

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Looks good to me.....the first sub always seems to take 30 mins dont you think?:(

I couldn't take my eyes off the PHD graph the whole time. It just *crawled* by while I stood, eating hot won-ton soup, in the dark, transfixed to the screen! :)

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MikeWilson

MikeWilson

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As it happens im on the Rosette at the moment, doing 20 min subs...yawn!

Your Image looks ok tho...well done!

Thanks - and I'll keep an eye out for your Rosette too! 20 minute subs, big yawn and for me at least the Meridian signals that it's time to go to bed. Can't be bothered with a flip tonight (I did set EQMOD to perform an 'auto flip', although it promptly ignored my wishes and proceeded to allow the scope past the meridian. Bah.).

Goodnight Martin, Goodnight everyone :-)

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ollypenrice

ollypenrice

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The nebula looks really beautiful, smooth and with the dynamic range done to perfection. However, what is that diagonal boundary skimming the right hand edge of the nebula and denoting a change in sky background brightness? I'll stand corrected but I've imaged widely around the Rosette and I'm pretty sure it's an artefact. Could it be LP? Your original had a big gradient but I'm not sure about the orientation. Do your flats show anything similar?

Olly

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MikeWilson

MikeWilson

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Thanks Olly and Tim,

I did wonder about that gradient. The full moon was up and so bright that I didn't need any torches to set up - brighter even than the light pollution by quite some way.

I think this might have caused it. I wonder if a manual lighten brush over the right side would fix this.

Thanks Tim for the tip, I'll give that a shot :)

All the best,

Mike

Sent from my mobile using TapaTalk (so please excuse bad grammar & spelling!) :-)

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MikeWilson

MikeWilson

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I've had this Ha filter a while, it used to screw onto the end of the Baader MPCC for DSLR imaging. It's well worth it since it gives you a chance during those clear moonlit nights. I'm going to have another go at the Rosette in RGB next to try making a HaRGB (no idea how yet!).

Sent from my mobile using TapaTalk (so please excuse bad grammar & spelling!) :-)

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AndyUK

AndyUK

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Hi Mike - Sincerest congrats on the 20 min subs - The result's superb :). I find that the longer subs capture much more signal which makes processing easier. Okay, capturing the subs does jangle the nerves a bit, but you get used to it (honest!)... and besides, I read somewhere that if you can get 10 mins without any visible guiding errors, then you can get much more. I won't challenge you to go to 30mins though - I reckon 20's enough

(PS - For my side of the challenge, I have got EQMOD theoretically working but only used it in daylight... I haven't had the chance to use it at night yet - Sadly Friday evening wasn't possible as I had "family committments" :). But it's on my list for next time... (promise!)

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MikeWilson

MikeWilson

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Hi Mike - Sincerest congrats on the 20 min subs - The result's superb :). I find that the longer subs capture much more signal which makes processing easier. Okay, capturing the subs does jangle the nerves a bit, but you get used to it (honest!)... and besides, I read somewhere that if you can get 10 mins without any visible guiding errors, then you can get much more. I won't challenge you to go to 30mins though - I reckon 20's enough

(PS - For my side of the challenge, I have got EQMOD theoretically working but only used it in daylight... I haven't had the chance to use it at night yet - Sadly Friday evening wasn't possible as I had "family committments" :). But it's on my list for next time... (promise!)

Good job on EQMOD! A bit of familiarity will help, you might lose a bit of time on your first couple of nights, bending it to your will, but it's

well worth it in the end. I'm glad you challenged me to the 20 minute subs, but I don't think I'll do 30. The max pixel value in these subs is around 55k, so plus a third more data and I'm probably going to over saturate some part of the image. 20's ideal, maybe 25 could be even better...

Likewise, I hope the slight nudge towards EQMOD is good for you too :-)

Very nice Mike.. Smooth as..

I presume you will overlay the Ha as Lum?

I know of a variety of choices for HaRGB / HaGB, but I'm worried about destroying the natural star colour.

Ha as Lum + RGB shouldn't effect the star colour but it might reduce the impact of the G/B channels, so I'd lose out on the broadband OIII, or would I?

I was thinking too of deleting the R channel and replacing it with Ha, or a blend of 60% Ha, 40% R, so that the contrast is improved but I don't cause stars to turn pink.

I have no idea, really. Suffice to say that I'll be doing 10 (or might drop to 15) minute subs for the RGB colour.

Sent from my mobile using TapaTalk (so please excuse bad grammar & spelling!) :-)

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AndyUK

AndyUK

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Hi Mike

Likewise, I hope the slight nudge towards EQMOD is good for you too :-)
Yes, I think we probably both knew that each of us were right, but we just needed that extra reason to tickle us on a bit further - Apathy is all too easy! Like everything else, I'm sure EQMOD will take a bit of a practice, and then exploring further when I've got it working (those free plug-ins sound very interesting!)

It's definitely worth playing around with the colour mixes though - An Ha,Ha/R,G,B definitely sounds worth a go, and as you say an RGB star layer will just top it off. I haven't yet sussed out what the correct exposure might be, but I was thinking of going for something between 5-10mins... Of course for you (with an OSC) it'll be a lot easier than taking separate filters, but fingers crossed for you for next time out, and I'm sure it'll be a cracking image when it's finished (maybe DBE will get rid of that gradient?)

(30 mins exposures...? I love the idea of them with NB, but I think I'll leave those to the likes of Tim!)

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