NGC 1404 and NGC 1399

[rogerg]

Hi all,

A quick 10x10min from last night.

Larger (100% frame):
http://rogergroom.com/wp-content/uploads/2013/11/NGC-1404-and-NGC-1399-10x600s.jpg

I'm happy with the image quality, just need to tidy up the blooms somehow and get some more data.

Regards,
Roger.

[Stevec35]

Looks pretty good so far Roger. It's a nice pair these two.

Cheers

Steve

[rogerg]

I should have also added that the thing I like most about images like this is the fainter galaxies detected in the background (presumably). I like seeing all those PGC's pop out of the woodwork.

[gregbradley]

Ah that looks nicer Roger. Much smoother with some nice Signal to Noise ratio. Are these longer subs?

Do you use bloom rejection in CCDstack or perhaps median combine with some dither between subs?

Greg.

[rogerg]

Yeap, the previous images were mainly 180s and 300s exposures this is 600s. As you say, there is a noticable difference. And it was dead easy providing there's a guide star, but not havinga guide star did rule out my first two choices in Fornax :(



The median with dither is interesting. All the subs are dithered so median may well help, I will try it. I did use CCD Stack (have now purchased a license, yay), and did use bloom rejection but I need to tinker with values it seems. I've already taken it down a lot from it's default of 45000 to 35000 but seems I need it to be even stronger rejection.

[Lee]

Nice image Roger.... I love watching the little faint fuzzies appear too... I did a basic lum image of the grus quartet (triplet for my FOV) recently - huge numbers of other little galaxies in the field.....

[gregbradley]

The median with dither is interesting. All the subs are dithered so median may well help, I will try it. I did use CCD Stack (have now purchased a license, yay), and did use bloom rejection but I need to tinker with values it seems. I've already taken it down a lot from it's default of 45000 to 35000 but seems I need it to be even stronger rejection.[/QUOTE]

Yes guide stars can be an issue. A MMOAG is handy that way as I usually can get a guide star without shifting the image too much.

Median combine is great for cleaning up images of residual noise and artifacts. Mean combine as mentioned in another thread generates slighly better SNR but it comes at a cost of dirtier images requiring Photoshop healing tool later! I am giving mean combine the flick. Too dirty even with a very clean camera.

Greg.