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Time Travel Research Center
© 2005 Cetin BAL - GSM: +90 05366063183 -
Turkey / Denizli
NGC 1499 (California Nebula)
Characteristics:
Magnitude: ?
Size: 1 x 4 degrees
FOV:
2.6 x 3.9 degrees
Distance: 1140
light years
RA (Jnow): 4h 01m 35s
Dec (Jnow): +36 degrees 25' 52"
Position Angle: minus 2 degrees
Description:
This is a 7.5 hour exposure of NGC 1499, a large hydrogen emission nebula in
Perseus. NGC 1499 is one of a few nebulae that emit strongly in both H
alpha (red) and H beta (blue), with little OIII emission, skewing the usual
red color typical of emission nebulae towards the blue. The star
responsible for exciting hydrogen emission from the nebula is thought to
be Xi Persei, a "runaway star" that is described on Rob Gendler's website.
Feel free to check out the larger size images above, as well as my H alpha
image used as part of this color composite.
Photographic Details:
Dates: September 16 and 20, 2007: Ha; September 17 and 18: RGB.
Scope: Takahashi FSQ106 at f5 on the Takahashi NJP Mount.
Autoguider: SBIG ST-402 with e-finder.
Camera: STL11K -20C.
Filters: Astronomiks LRGB set (50mm unmounted); Baader 7nm Ha filter (50mm
unmounted).
Exposures: Ha- 12 x 20'; Red- 10 x 6';
Green- 12 x 5'; Blue- 11 x 8'. Total exposure 7.5 hours.
Conditions: Temperature was generally cool
55-60 degrees F average. Transparency varied, and several nights of
exposure were need to obtain the very best frames for processing.
Post-processing: Calibrated, aligned, and Sigma Clip combined in Maxim,
followed by DDP in ImagesPlus (IP). Further processing in Photoshop CS (16
bit format). The RGB was constructed as usual. I then quantitated the
color of the nebula in PS using the color sampler (eyedropper) tool, noting
the relative proportions of R, G, and B. The Ha signal was then added to
the RGB in the following proportions (lighten mode), in order to preserve
the color balance determined by the eyedropper tool: Ha-Red, 50%; Ha-Green,
7%; Ha-Blue, 15%. In this way, the colors remained "true" to the original
RGB while at the same time allowing the Ha to enhance color and detail.
This enhanced "RGB" image was then used to provide the color, with Ha used
as luminance (i.e., Ha"RGB").
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