NGC5139 - Omega Centauri

[iceman (Mike)]

Hi all

This was taken on the Saturday night at Wee Jasper (well, actually Sunday morning). Saturday night had the longest clear spell, after the clouds parted at about 10:30pm. It was clear till about 2am, in which time I captured Eta Carinae (still processing) and Omega Centauri.

Unfortunately my run on Omega Centauri was cut short due to the clouds - I had a run setup to take 10x10s, 10x60s and 10x180s, but I only managed to get the 10x10s and 9x60s before clouds rolled in.

- Scope + Camera: ED80 + WO 0.8x reducer + unmodded Canon 350D.
- Mount: EQ6
- Guiding: Guided through 400mm f/5 refractor, using DMK21AU04 + PHD software
- Lights: 10x 10s + 10x60s @ ISO800, flats calibrated.
- Darks: ICNR used
- Flats: 15x 1/3s median combined
- Processing: ImagesPlus for Flats Calibration and Deep Sky stacker for registration and stacking. Photoshop for everything else.

I'm not happy with the image because there's absolutely no colour I needed the longer exposures to get the deep colours, but didn't get a chance.

Anyway, it's a tease for me for next time.

Thanks for looking.

[gbeal]

Seems burnt out centrally Mike, did you play with the Curves etc? I dug one of my old one out to make sure I was able to get the centre OK. (I was).

[iceman (Mike)]

I did layer the centre and in the full version there is resolution in the core, but it might appear burnt out in the smaller version, and also depending on monitors etc.

I'll have another play.

[browndog (Ian)]

There is certainly a lot of stars in this cluster and a shame that they are all the same colour . Damn those clouds...
This is still a nice image though and shows that your setup can take good deep space images too.

A technical question... How do you automate your exposures? You indicated that you "had a run setup to take 10x10s, 10x60s and 10x180s". I am assuming that you have a program that automates this? Is this correct?

[EzyStyles (Eric)]

A nice omega mike . I think you have used the levels abit too much causing the overexpo core of it. If you do an "S" curve from the stacked image, this willl prevent the overexpo of the core

[RB (Andrew)]

Shame about the weather Mike.

The core does seem blown on this version, could you link the full version so we can have a squiz.
I'm surprised though as I wouldn't have thought combining exp of 10s and 60s would blow the core.

Maybe try applying the curve function again, like Eric said, when creating the small version, but watch the histogram.

[beren]

Nice result Mike like you said shame about the star colours, wonder if you could draw something out using only the shorter subs or maybe drop the ISO next time out ?

[robgreaves]

Another trick that works well to bring out the core of Globular Clusters is the DDP (Digital Development Processing) tool, in the likes of Maxim/DL etc. Usually the default settings work fine in conjunction with a little levels adjustment. Stars will magically appear

I'm not sure though if you can feed a .jpg through that routine - I've never tried.

Regards,
Rob.

[Dietmar]

great cluster image Mike!

[iceman (Mike)]

Originally Posted by browndog

A technical question... How do you automate your exposures? You indicated that you "had a run setup to take 10x10s, 10x60s and 10x180s". I am assuming that you have a program that automates this? Is this correct?

Sorry forgot to answer this.

Yes - I use ImagesPlus which lets you automate a series of exposures. You can set the exposure time, ISO, filename and delay between images (and whether mirror lockup/in-camera noise reduction is set), and it will do the rest.

The files are automatically downloaded onto your computer too, so nothing needs to be stored on the camera.

You can set whether to display the image after it downloads it, so you can check the progress of each exposure - but if you're taking in RAW, it can take an extra 10-15s to convert to jpeg for display.