M101 (Pinwheel Galaxy) with associated NGC regions (rollover)

All Images Copyright Steve Cannistra

Please click here for a medium sized view (60%).
Please click here for the luminance channel used in this image.

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.

Photographic Details:
Date:  April 30, 2008 (luminance); May 14, 2008 (RGB)
Scope:  Vixen VC200L at f9 (FL = 1800 mm) on the Takahashi NJP Mount.
Autoguider:  SBIG ST-402 with Sky90 at f4.5.
Camera:  Apogee U32 -20C.

Astronomik 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.
Post-processing:  Calibrated, aligned, and Sigma Clip combined in Maxim.  DDP in ImagesPlus (IP).  Deconvolution in AIP4WIN as described above.  Further processing in Photoshop CS (16 bit format).
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