Messier 101 (Pinwheel Galaxy)
Characteristics:
Magnitude: Approximately 8.5
Size: 46'
Distance: 27 million light years
RA: 14h 3m 12s
Dec: 54 degrees 20' 25"
Description:
M101 is a large, beautiful spiral galaxy in Ursa Major. For
visual observation, it is best seen using a low power eyepiece under
dark skies. Despite being relatively bright at magnitude 8.5, it
has low surface brightest due to its large size. There are many
smaller, faint galaxies in this FOV. More information about M101
may be found here.
Photographic
Details:
Date: April 9,
2005
Scope: Takahashi
FS-102 at f6 with TOA-130 focal reducer, on the G11 Losmandy
Mount.
Autoguider: SBIG STV with
e-finder.
Camera: SXV-H9
Filter: Astronomik
Type II R, G, B, plus clear filter set.
Exposures: L:R:G:B.
160:40:30:40. Total exposure duration 4.5 hours.
Conditions: Temperature 50 degrees F, dropping to 37
degrees at end of session; good
transparency; average to poor seeing; clear.
Post-processing: No darks,
although bias-subtracted flats were used for this image.
Calibration and alignment
done in ImagesPlus.
Sigma
combined using RC Sigma Reject Plug-in for MaximDL. DDP was
performed in ImagesPlus. Subsequent
levels and curves adjustments in Photoshop CS (16 bit format). I
used the Dynamic Background Extraction tool (DBE) of PixInsight to
correct for color gradients in the RGB image, prior to combining with
luminance. Final sharpening done with a combination of several
techniques, including high pass filtering at a
radius of 1.5, unsharp masking, and Lucy-Richardson deconvolution
(selectively applied using layers).
Please
note: Graphics on this website may not be reproduced without
author permission.
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