M83 - H Alpha

[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 !

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

[strongmanmike]

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 :thumbsup: lovely to see all those HII regions standing out like that and a good job on the rest of the galaxy too :thumbsup:



NGC 1232 (http://www.pbase.com/strongmanmike2002/image/155863650/original) and NGC 253 (http://www.pbase.com/strongmanmike2002/image/146741809/original) lend well to the addition of some Ha to make the HII regions pop :thumbsup:

Mike

[gregbradley]

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

Greg.

[SamD]

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]

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

[tilbrook@rbe.ne]

Nice work Sam!:thumbsup:

Very interesting comparison.

Cheers,

Justin.

[SamD]

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]

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.