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M27 - THE
DUMBBELL NEBULA in "HUBBLE" COLORS Red = SII, Green
= Ha, Blue = OIII
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About
this Image:
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No,
this isn't a Hubble shot. But this image was acquired
and processed just like the gorgeous Hubble telescope
images that we've come to love. To accomplish
this, the image was taken through specialized, narrowband
emission line filters. This information was then
"mapped" to the traditional red, green, and
blue channels of an RGB image. The green portions
of the image represent Hydrogen-alpha ionized gases..
Most notably, these gasses extend well outside
the Dumbbell itself to form a halo around the outskirts,
something that requires very long exposures timesto
capture in an amateur image. The color blue represents
doubly ionized Oxygen gases, and as you'd expect from
a planetary nebula, the heaviest concentration of these
gases are around the core area itself. Finally,
red represents singly ionized Sulfur gases. While
the stars glow heavily in the sulfur wavelength, there
is only a light concentration of it in the nebula, mostly
throughout the brighter portions.
Such
images, while obviously beautiful, have a real scientific
purpose. Because the colors are mapped specifically
to certain gases, it's easy to understand the concentrations
of ionizations and how (where) they interact with each
other.
To see this same data in VLT-mapped
colors,
click
<here>.
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Location:
Ballauer
Observatory near Azle, Texas
Date: June 24th and 25th,
2005 Seeing:
9/10
Transparency: 2/10 (shot near
full moon phase)
Temperature: 69 to 72 degrees
F (camera at -15c)
Scope/Mount: 12.5" RCOS
RC and Paramount ME
Camera: SBIG STL-6303e astro
CCD camera Filters: Custom Scientific 4.5nm Ha,
OIII, and SII spectral line filters.
Exposure Info: Mapped
color image - SII/Ha/OIII - 120:300:80 minutes (20 minute subexposures
unbinned))
Processing Information:
Calibration,
Registration, Hot/Cold Pixel removal, and DDP in MaxIm DL 4. LR
Deconvolution on Ha channel in CCDSharp. Color mapping, cropping, color balance, levels/curves, sharpening, and
noise removal in Photoshop CS.
Exposure Notes:
This represents my first "mapped color" image taken with
narrowband, spectral line filters. The SII data is mapped
to the red channel, Ha to green, and OIII to blue. Seeing
was exceptional, in the 1" arc second neighborhood, but data
was taken near a full moon.
Copyright(c) 2003 - 2005 ALLABOUTASTRO.com. All
rights reserved.
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