The Great Nebula in Hydrogen Alpha
RA: 5h 35m 33s
Dec: minus 05 degrees 25' 29"
Position Angle: + 87 degrees
FOV: 4 x 3 degrees
The Great Orion
Nebula (M42) is the large, bright, central structure in the above field
of view. M42 is a stellar nursery
that forms the middle part of the Hunter's sword in the famous
It is a breathtaking view in even small telescopes, where
tendrils of gas can be appreciated even without the aid of special
filters. The use of a UHC filter improves contrast significantly
and reveals a
significant amount of faint nebulosity during visual observation.
The typical visual view in a telescope is pale white to faint
green, due to the human eye's poor color response to low light
in the red, which is emitted by this nebula due to excitation of
gas as a result of radiation from newly formed stars). As shown
above, the use of a hydrogen alpha filter with a CCD camera permits
capturing the full extent of surrounding faint emission nebulosity that
permeates this region. This image will ultimately be used in a
composite, once I have time and clear skies to acquire the color
data. Please click here
to learn more about M42.
Date: December 29, 2007.
FSQ106 at f5 on the Takahashi NJP
Autoguider: SBIG ST-402 with
Camera: STL11K -20C.
Filters: Baader 7nm
Ha filter (50mm unmounted).
Exposures: 9 x 20',
composited with 6 x 5' for trapezium region (which still could have
used less exposure).
exposure 3.5 hours.
Conditions: Temperature was approximately 35 degrees
F over the course of the night (focusing every 40 minutes).
Calibrated, aligned, and Sigma Clip combined
in Maxim, followed
in ImagesPlus (IP). Further processing in Photoshop CS (16
note: Graphics on this website may not be reproduced without
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