CCD/DSLR Experiment #2 - NGC6960 + M16

[Uranium235]

At long last, Monday night there was a break in the clouds after nearly two months of rain. It was so clear I could see the MW overhead.... great.. time for more experimenting! Wasted about an hour to start off with due to a schoolboy error in PA... doh!

Once sorted, the first test was to see if re-collimation would fix the reflection/halo I get when using the MPCC. Nope, it wasnt having it - still a nasty red blob appearing on bright stars and im pretty sure I know why. If you pick up an MPCC and look through it towards a bright light - then tilt it slightly - you will see exactly the same artefact that im getting, same colour too. This leads me to the conclusion that the 150P focuser isnt quite square and that no amount of collimation will get round that. Without the MPCC it performs great, just loads of coma! Anyway, I will give it one more shot before abandoning it in favour of an all refractor setup.

By about 2am I had to abandon the Veil for something a bit lower becuase I was getting a severe attack of dew of the ED80, which hasnt happened in ages. So I pointed the NEQ6 towards M16 to give it its first proper test of long exposure times, attempting my first 25min sub while the 1000d was left to snap 5min subs.

Would prefer more clear sky to test it further, but for now its working well enough

NGC6960 + M16

NEQ6, ED80, 150P, Atik 314L+, 1000d

First up, the Veil nebula data from the 1000d - a bit noisy and some coma as a consequence of using no MPCC. 9x600s, darks, bias and flats used

Next, lets see what happens if I mix 8x600 worth of Ha to Red, and 8x600 of OIII to blue and green (60/40 mix). The blend the combined Ha/OIII (monoised) to the DSLR luminence (50/50 mix). Less noise, but not at quiet as it would be if it were all CCD.

After having a severe attack of dew, I then slewed down to M16 for some respite and a quick test of the NEQ6 with long exposures. First was the 1000d data, just 5x300s so its noisier than a 2 year old.

Next was the thing that was the biggest winner of the night, the first time ive ever gotten past 20 minutes without eggs for stars. Here is just one 25 minute sub of M16 in Ha. I cant repeat the word that came out of my mouth when I saw this, but it would be great if I could get 16 of these. Just a few curves and levels to bring it out, no other processing. Not 100% prefect but the guiding was getting a little bumpy becuase of cloud that started drifting in.

Lastly, add the single 25 min CCD sub to the 1000d red channel (60/40), and to the luminence (50/50).

It just makes me wish I had two CCD cameras so I wouldnt be fighting the noise.

Thanks for looking

Rob

[nmoushon]

Great images and good luck with the MPCC!

[Steve Ward]

You should be able to adjust/square the focuser on the scope , adjustment screws are there somewhere although one is usually pretty hard to get at without a modified (i.e. cut-down ) Allen key

[steppenwolf]

I really like that second Witches Broom image - great combination. Such a shame that are having an issue with the MPCC - I have one and it works faultlessly but perhaps I have just been lucky.

[Gina]

Great images

[SJJ]

Now that's what i call a good night's work. Great captures.

[Uranium235]

You should be able to adjust/square the focuser on the scope , adjustment screws are there somewhere although one is usually pretty hard to get at without a modified (i.e. cut-down ) Allen key

Thanks Steve, thats something Ive already had a play with - and yes there is one very hard to reach screw (it almost wrecked my allen key!). I did try to square the focuser by levelling it then using a plumb bob from the peep hole of an old broken cheshire to find the physical centre - marked it then popped in a laser to see where the optical centre is pointing. So I adjusted the focuser, popped the secondary back on but then found I could not get the secondary to appear circular. So ive put it back to its default position of all screws fully tightened.

If its clear tonight I will give it one more try, but its doomed to be replaced soon anyway another ED80 will give me a lot less stress.

[BigBlueOne]

Fantastic images.

[Quatermass]

Nice to see some great images coming out after all this horrible weather, I am beginning to wonder if the sky is ever going to clear here in suffolk.

[Uranium235]

I really like that second Witches Broom image - great combination. Such a shame that are having an issue with the MPCC - I have one and it works faultlessly but perhaps I have just been lucky.

Thanks Steve, I dont think the problem is with the coma corrector itself because if it was mounted square to the light cone it wouldnt get that problem. About the only way I can think of adjusting it out would be to take a sub, tweak the focuser very slightly, take another sub and see if the blob has moved (thought it would probably knock my collimation out too).

Fortunately I now have a spare CG5 so I can do this on while the other mount is working, that way im not losing any time by tinkering.

[Zul]

Beautiful images!

[Shibby]

Great images Rob! There is surprisingly little coma given no corrector... did you use the lens correction filter or something?

That 25min sub is incredible, I can't believe it's a single sub! Bet you're pleased with that new mount

[Uranium235]

Great images Rob! There is surprisingly little coma given no corrector... did you use the lens correction filter or something?

That 25min sub is incredible, I can't believe it's a single sub! Bet you're pleased with that new mount

Cheers Lewis! Yeah, that NEQ6 is probably the second best purchase ive ever made (the Atik is #1). If I can get (or should I say afford) another CCD then it really will be a speed machine

The reason for the slightly reduced coma is that the 1000d subs were cropped to the same FOV as the Atik. But its still noticeable enough in the blue channel towards the corners. If youre going to SGL8, we should arrange for our pitches to be next to each other this time - it will be less distance for me to stagger between tents (especially after a couple of drinks!).

[michael.h.f.wilkinson]

Nice series of images. I did note the coma. Mind if some students test their coma (or more generally aberration) detection and quantification software on these images?

[Uranium235]

Nice series of images. I did note the coma. Mind if some students test their coma (or more generally aberration) detection and quantification software on these images?

No problem Michael, test as much as you like!

[Shibby]

If youre going to SGL8, we should arrange for our pitches to be next to each other this time - it will be less distance for me to stagger between tents (especially after a couple of drinks!).

Good plan - John and I are definitely intending to go again next year! And sample some more of the local ciders!

[farunj]

Wow!! Great photos!! Stunning!!