M83 - H Alpha

[SamD (Sam)]

I was surprised that Ha alone gives a fair bit of detail on M83. It really does pick out the numerous nebulae in its arms. This was 60mins at F/8 on an RC8 with an Atik314L+.

Popped the Ha on top of the LRGB (again on an RC8). A bit too saturated in red maybe in the Ha regions, but I felt I had to make the Ha data feel useful in the final result !

Looking forward to trying the same with M33 - anyone found any other galaxies with a lot of Ha regions ?

[strongmanmike (Michael)]

Originally Posted by SamD

I was surprised that Ha alone gives a fair bit of detail on M83. It really does pick out the numerous nebulae in its arms. This was 60mins at F/8 on an RC8 with an Atik314L+.

Popped the Ha on top of the LRGB (again on an RC8). A bit too saturated in red maybe in the Ha regions, but I felt I had to make the Ha data feel useful in the final result !

You know Sam, some might say from a purely aesthetic position it is a little strong but I like it and how cool does it look lovely to see all those HII regions standing out like that and a good job on the rest of the galaxy too

- anyone found any other galaxies with a lot of Ha regions ?

NGC 1232 and NGC 253 lend well to the addition of some Ha to make the HII regions pop

Mike

[gregbradley]

Yes there is a surprising amount of Ha in M83 and also NGC300. M33 may be very low in Oz.

Greg.

[SamD (Sam)]

Yes Mike, I think your NGC 1232 looks great with the extra Ha. NGC 253 and 300 do look worth running Ha too.

Greg, I suppose M33 is not so bad from Brisbane at over 30 deg above the horizon. Having tried M51 recently, galaxies near the horizon really are a pain - terrible seeing, you lose a lot of signal by extinction, and in my case you get a lot more light pollution to the north - end result is blurry and terrible SNR !

[Tandum (Robin)]

This has lots of detail but looks out of focus to me Sam. How do you focus the scope?

[tilbrook@rbe.ne (Justin Tilbrook)]

Nice work Sam!

Very interesting comparison.

Cheers,

Justin.

[SamD (Sam)]

Originally Posted by Tandum

This has lots of detail but looks out of focus to me Sam. How do you focus the scope?

Sorry, forgot to mention than the Ha image was Bin x 2, so will look softer against the LRGB. I didn't run a Photoshop SmartSharpen on the Ha either like I did for the luminance layer. Excuses, excuses, it could well also be out of focus !

I usually focus my RC8 manually, by slewing to a bright star and using a Bahtinov mask.

If I'm using my Atik314L+ I can also get good focus by using the stars in the field of interest itself. I just watch loop mode (1-2 secs) in the Artemis Capture, zoom in on a brightish star, and get it to occupy as few pixels as possible. This avoids having to slew off somewhere else when changing filter.

[Tandum (Robin)]

Ahh, it's probably the binning. Try grabbing some binned x 1 and double exposure time instead. There's not a lot of pixels on that camera.