M101 (Pinwheel Galaxy) with associated NGC regions (rollover)
Magnitude: Approximately 8.5
FOV: Approximately 19' x 28'
Distance: 27 million light years
RA (J2000): 14h 3m 10s
Dec (J2000): 54 degrees 21' 45"
Position Angle (Pinpoint): plus 24 degrees
M101 is a large, beautiful spiral galaxy in Ursa Major. This is
a deep, 8.7 hour exposure
taken on two separate nights with the U32 and VC200L. Please
check out the rollover which shows a number of NGC regions (many of
them are abundant in HII emission). I am pleased
with the detail revealed in this image after Lucy-Richardson
deconvolution applied to the luminance
channel (resampled x 2, AIP4WIN, LR in Fast mode, PSF using about
20 stars, 20 iterations, relaxation parameter at 0.5, process high
frequency components only, resample x 0.5). I have tried a
variety of deconvolution algorithms at this point and have settled on
AIP4WIN's, since I feel that it gives the best results. For
visual observation, M101 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.
Date: April 30, 2008 (luminance); May 14, 2008 (RGB)
Scope: Vixen VC200L at f9 (FL = 1800 mm) on the
Autoguider: SBIG ST-402 with
Sky90 at f4.5.
Camera: Apogee U32 -20C.
Clear (unblocked), R, G, B filters.
Exposures: Luminance 26 x 10' =
260'; R 20' x 4 = 80'; G 20' x
4 = 80'; B 25' x 4 = 100'. Total exposure 8.7 hours.
Conditions: Transparency good; seeing (FWHM)
approximately 3"; Temperature dropped to approximately 34 degrees
F during the night.
Calibrated, aligned, and Sigma Clip combined
in Maxim. DDP
in ImagesPlus (IP). Deconvolution in AIP4WIN as described above.
Further processing in Photoshop
note: Graphics on this website may not be reproduced without
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