Quick and Dirty Centaurus A

Paul Haese · #1 27-03-2011, 05:55 PM

Hi all,

I have wanted to re-image this object with the QSI for over a year but only just now getting to the task. Last night the skies co-operated for a while so that I could gather data before the moon rose. I gathered 2.2 hours of data but it really needs around 7 I think to make it look nice. This week I will go down a couple of times to get the data I need.

What I immediately noticed is that the data taken last night was a lot sharper than my 40D attempt. The luminence layer really shows its worth over the standard DSLR images. There is still loads of noise in the new image that I will address by gathering more data. Stacking needs some attention too; there is some weird shaped stars in the mix at the bottom of the image. Like I said this is a quick and dirty show of what I am looking at so far.

I hope Mike likes my rendition.

My old image for comparison

My new image of NGC5128

Feel free to comment and critique

Stevec35 (Steve) · #2 27-03-2011, 06:00 PM

A bit noisy Paul but I guess more data will fix that. Otherwise it's a very, very nice Centaurus A IMHO.

Cheers

Steve

jjjnettie (Jeanette) · #3 27-03-2011, 06:04 PM

Agreed, very nice.

gregbradley · #4 27-03-2011, 08:19 PM

Surprisingly sharp Paul. I can see why you were excited.

Are you sure that's not coma rather than stacking problems?

You may have to experiment with the spacing for your flattener.

Greg.

John Hothersall · #5 27-03-2011, 08:25 PM

The dust lane has very tight detail with more stacked this will really improve, faintest extensions will contrast out hopefully.

John.

Paul Haese · #6 27-03-2011, 08:58 PM

Quote:

Originally Posted by gregbradley

Surprisingly sharp Paul. I can see why you were excited.

Are you sure that's not coma rather than stacking problems?

You may have to experiment with the spacing for your flattener.

Greg.

Yeah no coma, on the subs the stars are round. The spacing for the flattener is exactly right for the TSA but has never been perfect for the GSO. It generally looks good but there is always some slight egging in one or two corners at any one time. More likely tilt is the issue here.

SkyViking (Rolf) · #7 27-03-2011, 09:08 PM

That's an impressive image, very well done. I think it has a lot of depth, with a very sharp dust lane, and the star colours are beautiful too.
I'm looking to purchase the QSI myself later this year, so it's good to see such solid images taken with this camera

mr bruess · #8 27-03-2011, 09:09 PM

even small amateur telescopes can produce good images compared to the big observatories.

Paul Haese · #9 27-03-2011, 09:17 PM

Thanks all for the comments and suggestions. Rolf the only problem I have found with the camera really is the cooling. During the peak of summer on hot nights I can only get -15C on the sensor. This data was taken at -20C and the level of noise visible is like chalk and cheese. The rest of the camera is great and well designed. I have made a few requests about improving the cooling and it might well come to pass that QSI gets this issue sorted.

Bassnut (Fred) · #10 27-03-2011, 09:50 PM

Well, Ill stick my neck out and say this is a considerably more detailed rendition than Mikes effort (zoomed in) despite the very slight noise.

"quick and dirty" doesnt do it justice, its a cracker !.

Paul Haese · #11 27-03-2011, 09:56 PM

Hey thanks Fred, appreciated. I have now taken care of the star shapes with a re-stack and reprocess.

allan gould · #12 27-03-2011, 10:04 PM

Paul
You are squeezing the living daylights out of that 8" scope - really, two great images. I can't wait to see what you can do with the 12"

strongmanmike (Michael) · #13 27-03-2011, 10:17 PM

Not a bad start Paul but I actually like your 40D image better at this stage, it has better colour and more spacial depth in the image. I think ithe latest image will improve with more exposure as you say. There haven't been too many Cen A's so far this season, I think Doug got in first though.

Haven't seen him in this section for a while and his first post back and as usual I think Fred (

) is trying to get me to bite

but I am strong

Mike

Paul Haese · #14 27-03-2011, 10:38 PM

Thanks guys,

Allan, looking forward to that too mate. More light and resolution will be much appreciated.

Mike, no problem, I hope to get more data in the coming week or so. Weather permitting.

marc4darkskies (Marcus) · #15 27-03-2011, 11:13 PM

Hi Paul,

Your DSLR image wasn't shabby at all but the CCD redo looks much better IMO (as you'd expect really)! Very sharp but a bit noisy as you say and lacking a bit in colour depth. Nothing that more data won't cure though ... but you know that already

. Nice one!

Cheers, Marcus

TrevorW · #16 28-03-2011, 12:40 AM

Not bad Paul, the level of detail is excellent and can only improve with more data, as has been said.

Cheers, Trevor

Phil Hart · #17 28-03-2011, 01:24 AM

that is very nice paul.. the detail is very impressive, especially after looking at the DSLR version.

am i right in saying that you've cropped the displayed QSI image a little more than the DSLR image? the contrast, particularly for the stars, looks much better in the DSLR image which is presumably mainly the result of stretching limited data hard?

if you can maintain the detail you have in the QSI image and get back the nice star/background contrast and sharpness you have in the DSLR image by getting more data then it really will be a cracker..

Phil

Hagar (Doug) · #18 28-03-2011, 08:31 AM

Nice Paul. I don't know about quick and dirty. It looks pretty good to me. There is always going to be the little things in an image which detract a bit but thats the joy of having a moving atmosphere full of water vapour. Noise is a fact of the above and I would much rather see a bit of noise than an overly smooth manufactured rendition.

Well done. Detail is great.

SkyViking (Rolf) · #19 28-03-2011, 09:13 AM

Quote:

Originally Posted by Paul Haese

Thanks all for the comments and suggestions. Rolf the only problem I have found with the camera really is the cooling. During the peak of summer on hot nights I can only get -15C on the sensor. This data was taken at -20C and the level of noise visible is like chalk and cheese. The rest of the camera is great and well designed. I have made a few requests about improving the cooling and it might well come to pass that QSI gets this issue sorted.

Ok I see. Yeah the cooling is not it's strongest point unfortunately. Are you finding that it cools less than the advertised -38 from ambient? Or is it the generally (I presume) high ambient temps in your location that are a challenge?
I'm hoping it won't matter to much for me, as I'm based in Auckland. Our hottest summer nights are around 20 degrees, maybe 21 when it's really extreme. But that's only for a few weeks right at the peak of summer, so I could live with a bit of extra noise during that period. It's also the time of year when the nights are the shortest, so I usually put off deep imaging then.
At the moment we have around 10-15 degrees over night, and in winter it drops to 0-5 degrees for a prolonged period. I'm not sure how that compares with what you are experiencing though.

Paul Haese · #20 28-03-2011, 09:27 AM

Thanks guys,

Phil, this is a very slight crop, however without the cropping there is a definite image scale jump from the 40D to the QSI. The pixel size is pretty much the same so it much be just real estate that causes the scale change.

Rolf, yes the -38 from ambient is spot on. It is warm nights that are the killer. Temperatures of 26 degrees of a night time mean that -15C is possible but you need the water cooling to keep a good head room. In your neck of the woods it would be ok most of the time and you might even be able to achieve -20C on your warm nights.