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Messier 101

Optics TEC 140APO with Flattener at f7.2
Mount AstroPhysics 900GoTo
Camera STL11000M
Filters Baader LHaRGB
Date February-May 2012
Location Antares Observatory
Sky Conditions mag 5 sky
Exposure LHaRGB = 24.3,5.3,5.8,4.7,5.5h
total: 45.6h
Programs used PixInsight, Photoshop CS4
Notes First light of TEC140APO

My goal with this image was to show the extremely faint outer spiral arms of Messier 101. A master Luminance channel was created using all the luminance and color filtered images. The resulting image includes more than 40 hours of data. All frames were captured at a time when M101 was near the zenith in order to keep the atmospheric extinction and effects from light pollution as low as possible. Click on the thumbnails below to find some crops in 100% and 150% resolution:

M101 Crop1 M101 Crop2

M101 Crop3 M101 Crop4

An interesting feature is visible around NGC5485. Up to now it is not clear if the stellar-stream-looking structure is really associated with the NGC5485 or if it is a foreground nebula. If you have any information regarding this object, please drop me an email! Below you find an inverted image from luminance dat at 100% resolution showing the circular stellar stream candidate around NGC5485 and an additional possible associated structure to the left. North is to the right.

NGC5485 inverted


click here for a 70% size image, 2764x1824 (3262KB)

The total luminance image (2410 minutes) is shown below on the left and an inverted image for better visibility of the faint outer spiral arms is shown on the right side. Click on each to find a larger version.

Beside the faint spiral arms a faint background nebula is visible. This galactic cirrus becomes prominent when the image contrast is strongly enhanced. This however also enhances possible image calibration errors (i.e. flat field calibration). Although image calibration and background correction was done very carefully, some of the structures might still be due to bad image calibration. A comparison of the IRAS survey images (low resolution) however confirms most of the structures seen here.

Messier 101 luminance Messier 101 inverted

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