Nova Remnant in Taurus
Instrument: 12.5" f/5 Home made Newtonian
Mount: Astrophysics 1200 QMD
CCD Camera: SBIG 10XME NABG with Enhanced Water Cooling
Guider: Meade DSI Pro w/Lumicon Newt Easy Guider
Exposure: RGB = 40:40:40 Ha+RGB = 170:40:40:40
AstroDon RGB Combine Ratio: 1: 1.05: 1.3
Location: Payson, Arizona, Elevation: 5150 ft.
Sky: Seeing FWHM = 5 arcsec (Maxim DL - 10min subframe), Transparency 9/10
Outside Temperature: 35 F
CCD Temperature: -30 C
Image Processing Tools:
Maxim DL: Calibration, deblooming (Starizona Debloomer), aligning, stacking
Gralaks Sigma: Stacking
PixInsight: Curves, Deconvolution, noise reduction
Photoshop CS2: Curves, Color Correction, Gradient removal (Grad Xterminator), Cleanup
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This pair of images
represents the most detailed I've taken of this object so far
with my 12.5" f/5 from Payson. Extreme care was taken to
ensure a proper visual G2V color balance on both images. The
technique will be discussed below.
The Crab Nebula in Taurus is a super nova remnant that exploded
in in the year 1084AD and has been rapidly expanding ever since.
It is located a degree from the easternmost star in the Bulls
horns, and glows dimly at a magnitude of 8.4. While small at
6 arc minutes, it is typical of the size of many galaxies in
my telescope, and thus made a good target for my galaxy hydrogen
enhancement technique. Look carefully at the lower left of this
image, you will see a passing asteroid Anahita. It was 12.2 magnitude
at this time, and was the 270th asteroid ever found.
The Colors in this Image:
The diffuse core of the Crab is produced by the light of high
energy electrons and is called synchrotron radiation. It will
photograph as nearly a continuum, white in color, sometimes with
a very pale blue tint. Surrounding this core are the filaments
of hydrogen, a pink hue extending over the entire nebula and
beyond the inner core. The outermost edges, seen primarily on
the left side of the right hand image has a bluish cast or rim.
This is from OIII emission, with some H-Beta and Sulfur II light.
The stars across the frame show the full spectral range, from
deep red M stars to blue super giants.
Producing these images:
As most of you know, I am an extremist when it comes to doing
my best to produce accurate colors as the eye might see them
when imaging deep sky objects. The CCD filters were calibrated
on several G2V sun like stars for producing a white image. Once
this white point was set, most images will record with true coloration
- with some offsets of coarse from emission lines falling near
band stop edges. The LEFT image was a standard 2 hour Red, Blue,
and Green set of exposures combined with the exact G2V ratios
to produce a fairly accurate representation of the crab in visible
The image on the
right is the same image with an additional 3 hours of hydrogen
alpha light exposure data added in a very specific way. While
the technique is detailed in my AIC article from last year, essentially
it is to add the hydrogen data using screen to each color channel
in a proportion of 100%, 8%, and 4% to the RGB. Then the MOST
important part - I then re combine the original G2V color balanced
RGB image over this hydrogen enhanced image using HUE. This fully
restores that hard earned color balance to the nebula, the filaments
and core. This technique allows the common astro imager to bring
in new details that were previously hidden in the old RGB techniques.
Now we can show much more than ever before in the nebulas faintest