Omega Centauri, count the stars

[Paul Haese]

Just a short lot of subs for this object and I am quite pleased with it. my guiding appears quite nice and the resolution of the scope is pretty good I think. Not entirely sure about the star colours though. I thought that Globs contained old stars and therefore blue stars could not be present. This does not seem to be the case here. Is there something I have done wrong here?

Click Here for Image.

Comments welcome

[toryglen-boy (Duncan)]

maybe its just me Paul, but despite the lovely colours in this, the focus seems a bit soft, or am i going mental?

[Paul Haese]

Yeah your right, the focus is just slightly off. Might be have been the seeing too. I will do some sharpening to the stars and see how that looks.

[Paul Haese]

Duncan how does that look now? I could not get all the defocus out but this is a compromise between sharp and slightly out of focus. Unless any gurus have any tricks they care to reveal?

[toryglen-boy (Duncan)]

i should think there are few here that could advise you mate

[SkyViking (Rolf)]

Great image Paul. There are indeed blue stars in globular clusters and they are an interesting phenomenon. See this thread for details: http://www.iceinspace.com.au/forum/s...ad.php?t=56370

Regards,
Rolf

[avandonk]

Originally Posted by Paul Haese

Duncan how does that look now? I could not get all the defocus out but this is a compromise between sharp and slightly out of focus. Unless any gurus have any tricks they care to reveal?

Paul do you dither between exposures? By stacking randomly dithered upsized (use cubic interpolation x1.4 to x1.60) images you effectively double the pixels on your sensor. This works very well when undersampling ie the tiny dim stars. Small or dim stars actually can be recorded at better than the Dawes limit with a high quality optic. At your image scale seeing of course is a factor. Richardson Lucy deconvolution if used sparingly also helps.

Blue stragglers are now thought to be stars that have collided and combined into a higher mass and hotter star. I have often wondered about the red one clearly visible in your image.

Bert

[Paul Haese]

Bert no dithering between exposures. Perhaps I ought investigate this, but knowing the EM400 and Tak this will be another thing I cannot do with the mount due to electronic hand controller short comings.

I was a bit under sampled though as I was 2x2 binned for this image. Perhaps I should have been at 1x 1 and that would have given me a better resolution. Completely forgot all about that.

Thanks Bert

Thanks for the link Rolf.

[astroron (Ron)]

Paul, one of the reasons Omega Cent is thought to be the remains of a dwarf Galaxy is the large number of Blue stars compared to older sun like stars