Alt/Az Eta Carina Nebula NGC 3372

[wayne anderson]

Shots taken from a dark site at Pratten QLD on 12/11/2012
The sky was very dark and almost perfect seeing, I spent so much time absorbed in viewing with the eyepieces that I only had time to shoot this one object before packing up.

90 x 20sec subs at ISO 1600
20 Darks, Flats and Bias
Stacked in DSS

12” LX200 (alt/az setup no guiding)
Sony Nex-3 Camera

To stack the 90 files for a change I set DSS to Median Kappa-Sigma Clipping (Kappa 2.0 & 10 iterations) for all Lights, Flats, Darks and Bias, then processed the stacked file in Corel Photo-Paint 7 ( release 1996, its an old program but works ok for now)

Amazing, I was not expecting this result there was only 30 minutes of data from 20 second subs (20 secs keeps field rotation smaller) and the scope was in alt/az mode with no guiding at all, just standard tracking and no PEC training (I will need to learn to do this soon)

Later I will try using a de-rotator or wedge with auto-guiding and good polar aligning to improve the results, then get a better camera, for now this setup will have to do (no $$ for astro gear or new software)

[LewisM]

Geez Wayne, you are copying me :)

Shot a good while back with an ED100: http://imageshack.us/f/7/closeupcore.png/

Single 10 min sub.

If you have a dark spot in Landsborough, please share :) Only 10 min drive for me

[alpal]

Hi Wayne,
it looks like you have good data but your processing has problems.
The black looks clipped & the stars are all white - burnt out.
The stars should never be burnt out on short 20 second exposures.
You really need Photoshop to be able to adjust the curves properly.

If you supply a link for the stack - I'll have a go at it for you.

[Ross G]

Nice capture Wayne.

Ross.

[Larryp]

Great shot, Wayne!

[jjjnettie]

:) It's amazing how much data can be collecting in such short subs. :)
Congratulation on a great image. :)

[wayne anderson]

Thanks Laurie, Ross and JJJ

Sorry Lewis I don’t have a dark site at landsborough I have 5 bright street lights less than 100 meters from my backyard. I have been looking for a dark site near by, but found you really need to go over the other side of the range past Conondale, Rons (astroron) place at Cambroon is ok, I am still looking for a dark place closer to home, if you find one let me know.


Thanks alpal for your advice, I ditched using Corel to process (it’s a bit old and rough) then downloaded GIMP (its free) and reprocessed the image. The final stacked image still has the stars blown out just a little bit but gimp is a little more sensitive and forgiving to use when processing, I an still learning my way around using gimp.

These are the close up crop image (1), processed with gimp (2) and original stack image resized (3)