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© 1998 Cetin BAL - GSM:+90 05366063183 -
Turkey / Denizli |
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M27 in Hubble Colors
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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.
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DETAILS: Imaged with the 12.5" Truss RC (RCOS
Optical Systems) July 20, 2004, using a Precision Instrument Rotator to find
the brightest guide star, at f9, with unbinned Luminance, and guided by the
AO-7 on a Paramount ME German Equatorial Mount. Camera is an ST-10XME.
Luminance is two and one-half hours, with 30 minutes each of LRGB binned 2.
All allignment of reduced frames (bias, darks, flats) done in RegiStar.
CCDSharp, MaxIm DL, and Photoshop CS with a variety of plug-ins used in the
processing. RGB combine ratios were 1:1.1:0.9 using AstroDon TruBalance
filters. COMMENTARY: M27 is a bright, well-defined, and popular imaging
target in the Constellation Vulpecula. It is a planetary nebula resulting
from the demise of a sun-like star through the various evolutionary stages
to its present white dwarf status, puffing off its outer atmospheres and
bombarding the gases and dusts with high-energy illuminating radiation,
causing expanding shock waves. M27 is approximately 800-1000 light-years
distant, about 2-3 light-years in diameter.
M27
- The Dumbbell Nebula
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About this Image: |
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This is an attempt to take
spectral line emission data and use the same techniques as the well-known
European Southern Observatory (ESO) image (see below) taken back in 1998
on the newly constructed 8.2 meter VLT scope. While the above image was
taken with much less aperture, the instrumentation is so sophisticated
in such scopes that it's rather remarkable! Of course, the ESO image
used only 5 minute exposures for each component!
The only difference between the two images, other than the general
quality, is that the ESO image used a broadband filter to capture data
for the blue channel while the above image uses singly ionized Sulfur
data for blue (with a hint of Ha data to simulate H-beta gases). Otherwise,
Ha is mapped to red and OIII is mapped to green in both images.
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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 - Ha/OIII/SII - 300:80:120
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 is a re-mapping of the same color data used in the
Hubble colors image. The Ha data is mapped to the red channel, OII to
green, and SII to blue. Some H-alpha data (15%) was blended into the blue
channel as well to imitate H-beta emissions. Seeing was exceptional, in the
1" arc second neighborhood, but data was taken near a full moon.
Astronomi
Nebula Resimler
Astrophotography
Galaxy Resimler
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