Arp 245

[sjastro]

Like most Arp galaxies this is a tough object to image.

Eight hours total imaging time which is deep by my standards.

L( lRGB ) exposure. L=5 hrs, l= R+G+B, R=1 hr, G=1 hr, B= 1 hr.
BRC-250, ST-10XME.

http://users.westconnect.com.au/~sjastro/arp245c.html (http://users.westconnect.com.au/~sjastro/arp245c.html)

Clear skies

Steven
http://users.westconnect.com.au/~sjastro/small (http://users.westconnect.com.au/~sjastro/small)

[jase]

Lovely composition Steven. Incredibly smooth data due to the long integrated exposure times. Not sure about the colour balance however... The red channel is black clipped and the green halo around the bright yellow star doesn't look too aesthetic. I'd really like to see a reprocessed version of this image. It has the foundation of something special, just needs some extra attention.

Cheers

[EzyStyles]

very nice steven. that wouldn't happen to be the siamese twins? or the eye galaxies?

[sjastro]

You are quite right Jase.
I have completely redone the image except for the halo around the bright star. Removing halos from stars has always been difficult.

Regards

Steven



Hello Eric. This one doesn't have a name. It's a very faint interaction between NGC2992/93 galaxies. A catalogue of peculiar galaxies was composed by Hamilton Arp in the 1960s.

Regards

Steven

[marc4darkskies]

I'm with Jase - lovely image Steven. I'd even consider cropping the bright star out - it takes attention away from the Galaxies.

I've tried adding synthetic L too to try to make up for subs that were too short. I think it helped. Why did you do it in this case? When you say L=5hrs, does that mean 1hr of R+G+B + 4hrs of L? What length subs did you use? Also, did you do any sharpening on the galaxies?

Sorry for all the questions ... :ashamed: ... I'm in the middle of a new project myself and I like to know how the experts do it! :D

Cheers, Marcus

[Bassnut]

Is this the redone image?, smooth and a nice "warm" feel.

[sjastro]

Thanks Fred. The link is for the latest image.

Steven



Hello Marcus,

I performed LRGB combining in two stages. The first stage is using a synthetic L (R+G+B) image and combining with the RGB images. The resultant (R+G+B)RGB colour image has a much higher S/N ratio than the RGB image.

The second stage is to split the (R+G+B)RGB image into R, G and B components and combining with the 5 hrs of luminance to form a conventional LRGB image.

All my individual images are of 10 minute duration. I use selective sharpening with the smart sharpen option in Photoshop. If there is colour noise in the final image, I will apply the noise reduction option in Photoshop to the R, G and B channels. This very effective in reducing colour noise without effecting the overall sharpness of the image.

If the image requires greater saturation an effective method without increasing colour noise is to convert the final image into an Lab image and applying an increase in contrast to the a and a channels. The image is then converted back to RGB.

Hope this helps.

Regards

Steven