The Great Nebula in Hydrogen Alpha
Characteristics:
RA: 5h 35m 33s
Dec: minus 05 degrees 25' 29"
Position Angle: + 87 degrees
FOV: 4 x 3 degrees
Description:
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
constellation Orion.
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
(especially
in the red, which is emitted by this nebula due to excitation of
hydrogen
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
new HaRGB
composite, once I have time and clear skies to acquire the color
data. Please click here
to learn more about M42.
Photographic Details:
Date: December 29, 2007.
Scope: Takahashi
FSQ106 at f5 on the Takahashi NJP
Mount.
Autoguider: SBIG ST-402 with
e-finder.
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).
Total
exposure 3.5 hours.
Conditions: Temperature was approximately 35 degrees
F over the course of the night (focusing every 40 minutes).
Post-processing:
Calibrated, aligned, and Sigma Clip combined
in Maxim, followed
by DDP
in ImagesPlus (IP). Further processing in Photoshop CS (16
bit format).
Please
note: Graphics on this website may not be reproduced without
author permission.
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