gold price: [SBIG] Re: Boosted Red Tendrils in M82

Minggu, 24 Februari 2008

[SBIG] Re: Boosted Red Tendrils in M82

Hi Steve,

It looks like you have some excellent data to work with. That
Keller/Wynne corrector is really doing the job, the level of detail
is outstanding. However, in your quest to bring out the tendrils you
have washed out the interior of the galaxy. There also seems to be
some extra red scattered about in the background.

Here's a process to think about.

First separate your Ha filter from the luminance. Taking separate
exposures for the Ha will give you much more control. With the ST-8
camera I would take 30-min Ha subs, binned 1x1. With the ST-10, I
don't know what to suggest for the exposure, but I hear it is an
excellent camera for Ha data.

After processing the five channels, with PhotoShop, I would layer the
Ha data on top of both the lum and red channels. For a galaxy I
would set the opacity for the Ha data to about 20% and combine the
layers with the lighten option. This way you can get both the
tendrils from the Ha data and the stars combined in one image. Now
with the Ha data added to the lum and red channels, I simply do a
normal LRGB combine.

This is how I got the hydrogen areas in my NGC 2903 image to come
out. The image is at URL http://bf-astro.com/ngc2903.htm, but it's
not nearly as good as your 2903. That fast Newtonian, with the
corrector, is really giving the RC scopes a run for their money.

Just a thought,

Bob Franke
http://bf-astro.com

--- In SBIG@yahoogroups.com, "Steve Bell" <sb635@...> wrote:
>
> I tried a technique to record more of the red tendrils shooting out
of the core of M82:
>
> http://sb635.mystarband.net/m82_lab_mpc_1_39_boost.jpg
>
> I duplicated the image and did a Curves to brighten the tendrils.
Of course, this brightened everything. I cut out a circular region
surrounding the top brightened tendril, and cut and pasted it into
the original image, with feathering. It looked like it blended in
nicely. I did the same for the bottom tendril. Then I did the whole
thing again, to give a double boost. Sometimes, though, when playing
these tricks, a banding pattern will show up around the borders of
the cut and paste region if you are not careful. A good way to see if
this has occurred is to invert the image, I did, I didn't see any
problems, but that's only on my monitor.
>
> To see the original without the boost, go to:
>
> http://sb635.mystarband.net/m82_mpc.htm
>
> I admit, there's not a gigantic difference, but every little bit
helps.
>
> Steve
>
>
>
> [Non-text portions of this message have been removed]
>