Centaurus A reprocessed

[wayne anderson (Wayne)]

I decided to restack and reprocess my original Centaurus A data, this time with the extra subs that DSS rejected the first time and now with darks and bias to reduce noise so I could squeeze more out of the original data.

I seem to have some difficult colour gradients to deal with and I am still learning how to smooth them out, the gradient looks better when reduced to grey scale so think more data is needed and next time flats as well.
　
144 x 25sec subs at ISO 1600 (total 60mins alt/az no guiding)
darks & bias
12 " LX200 (alt/az setup)
Sony Nex-3 Camera
Stacked in DSS edited in GIMP

[5ash (Philip)]

Looking good Wayne , like the second one best . Have taken pics of it unguided with a variety of setups in the past but now I've got off axis guiding working on my ed80 will now progress to using it on my c9.25" with my nex5. then Centaurus A will be in my sights again.

Ps what settings do you use in DSS for your nex3 pics? I also see we are not to far away from each other.

[wayne anderson (Wayne)]

Thanks 5ash,

I see you use a Sony Nex-5 camera, they seem to give good results I have been impressed with my Nex-3 its old but ok considering I got the camera so cheap.

I am iterested in how you setup the OAG I am looking at setting up a field de-rotator and OAG on my 12'LX200 soon.

I use the standard jpg files from the Sony Nex-3 camera because when i tried the Sony arw files DSS could not use them, this is the usual settings i use in DSS

Register settings: star detection 2% , with median filter
Stacking settings:
Result: mosaic mode , align RBG, use all processors
Light: Auto Adaptive, 10 iterations, RGB calibration, debloom
Dark: median kappa-sigma cliping, kappa 2, iterations 10, hot pixel removal, dark optimization
Flat: median kappa-sigma cliping, kappa 2, iterations 10
Bias: median kappa-sigma cliping, kappa 2, iterations 10
Alignment: auto

sometimes the final stacked image has strange RGB levels and needs the RGB levels adjusted before saving to process in GIMP.

[5ash (Philip)]

Hi Wayne ,
Thanks for the info on DSS settings , will try them. Did you get advice on these or find them by experimenting? I use the beta version of DSS as it supports Sony ARW files. JPEGs are a lossy picture format and you lose data when you manipulate them . With the beta version of DSS you should get even better pictures. Will be able to advise you of my experience with off axis guiding when your ready. Could even show you the setup I have here in Pelaw main near kurri kurri. You said you are looking at a field derotator as well , if your handy you might try making a wedge and forget about the derotator. I had an lx90 a few years ago and was managing to get a about 60% of pictures at f6.3 , with nice round stars, unguided for 2+ minutes using a homemade wedge aligned on the asterism of stars in octanis , situated around the S celestial pole. If I had used a guider they would have been perfect.
Regards philip

[Meru (Michael)]

Wow, you must have *amazing* night skies and/or great seeing when you captured this. That's alot of fine details, very good!