NGC3372 - Core of the Eta Carina Nebula with Dual NB

[Doogs38]

G'day folks. Looking at recent posts it's obvious the Carina Nebula is popular, and rightly so as it's magnificent. But rather than do a widefield image I've got somewhat closer to the nebula's core ... and continued learning to image with my new SCT setup (now with 0.7 reducer). Also learning the essential art of SCT collimation using a tri-baht mask.

The resultant image is from two sessions; I lost about 2/3 of the 1st session's subs due clouds. 2nd session was great. Total integration is 3hrs 10 mins and I'm quite happy with the final image which has lots of detail when viewed full size (here: https://pbase.com/image/173297695)

Key things I learnt are: 0.7 reducer introduces mild chromatic aberration, and, also distorts guide stars when viewed via an OAG (but PHD2 still guided perfectly). Subsequent research shows both are common. Regardless, I'll keep using the reducer as imaging at 1422mm is easier than 2032mm!

As always, thanks for looking. Alex

EdgeHD 8", 0.7 reducer
95 x 120s, Antlia dual NB, ASI294MC
D, F, DF. PI & PS

[AstroViking]

Hi Alex,

Yeah, Carina is a popular target, being so big and bright. There's a lot of detail in there to be found, and the brighter stars make it a challenging subject. It also looks damned good.

Your image is great - I had a trawl through all the little swirly bits in the gas/dust cloud and it's fascinating to think just how big they really are.

I can't wait to see your next image.

Cheers,
V

[Dave882]

Really lovely shot and very well processed. I particularly love the area directly around eta Carinae - you can see the shape of the Homunculus Nebula lobes and some surrounding g detail that is often lost in many images. Great job!

[oska]

Great shot Alex! Glad to see you gettin' some good star time lately :thumbsup: The crescent stars (fixed mostly later) in the OAG were very off putting to me (worked fine) and it's funny, but when I went back to a guide scope the round stars felt like a breath of fresh air - weird :)

Indeed the detail is fantastic. Well done.

[xelasnave]

Great capture ... I want one but then I would need your skill..well done..
Alex

[Bodon]

A very nice pic!

[Dilsh]

Fantastic shot Alex. Great minds think alike. I am literally shooting the same target tonight.

Looks like you are really getting you head around the new scope. Well done. You give me hope.

Love the natural colour in this image. Where are you shooting from? What kind of Bortle are your skies?

Cheers,

Dilshan

[Doogs38]

Thanks everyone. The more I look at this one the more I like it despite the corners looking a little weird due to the sensor being too close. I did have the 'correct' back focus according to Celestron and ZWO. I've since added an extra 1mm of back focus and will see how that goes.

Dilshan - image was taken from my suburban backyard which is in a Bortle 5 zone. Interestingly, my attempts at stretching the image and colour/saturation correction were not as good as PI's auto-stretch process ('STF') - 1st time that's happened. So, I just transferred the STF parameters to the image histogram as a basic stretch and then edited the resultant non-linear image.

Alex - you have great skills mate! In fact, this was my first attempt at shorter exposures with higher gain. I did this based on your experiments from which I've learnt a lot. Instead of using 5min exposures at 120 gain, I used 2min exposures at 240 gain and couldn't be happier with the result; it seems to produce less noise (although I've not tested that hypothesis) than using longer exposures with lower gain.

John - I managed to fix (yaaay) the weird shaped guide stars by spending a bloody long time precisely focusing the guide camera in the OAG.

Dave - I too noticed the double lobe of the Homunculus in the stacked image and jeeeeeez I tried hard to get some detail out of it. But it was too overexposed. Made me wonder if a different optical train (for planetary?) might get in close enough to get some detail using very short exposures and 'lucky imaging' techniques?

Steve - I'm a sucker for little swirly bits in the gas/dust! I'm enjoying the SCT's longer focal length to get in closer to such things. I did try using my ASI482MC planetary cam to get even closure but the ASIAIR had trouble plate solving the very narrow FOV. At least I tried :lol: