M101

M101, Wide Field

M101, NGC 5477

M101 in Ursa Major is a beautiful, large, face-on spiral galaxy of the type Sc, meaning it has extended spiral arms and a very small central bulge. Like in other large nearby spiral galaxies, several knots of emission nebulosity can be recorded on deep photographs. The galaxy is quite near, at a distance of only 18 million light years, and is the center of a small group of galaxies with 23 known members, mostly dwarf galaxies. This is a neighbor group to the Local Group of galaxies, of which our Milkyway Galaxy is a member.

If you examine the image above closely, you can spot a few background galaxies. The brightest of these is NGC 5477, an irregular spiral galaxy of the Magellanic type. It can be found not far fron the left edge, above the center.
M101 and Surrounding Galaxies, refractor photograph.
M101, an enlargement of part of this photograph.

Exposure Data

Instrument: 9.5" f/4.9 Newtonian
F/stop: 5.6
Exposure: 12 x 10 minutes + 2 x 2 minutes
Camera: Canon 350D with Baader UV-IR-Cut-Filter
Sensitivity: ISO 800
Date: May 30, 2008 / April 12, 2009 / May 24, 2009
Exposure start: 23:43 MESZ / 22:40 MESZ / 1:32 MESZ
Location: Ebenwaldhöhe, Lower Austria / Ebenwaldhöhe, Lower Austria / Oberleiserberg, Lower Austria
Conditions: Visual limiting magnitude 6.0 mag, seeing 2.8" FWHM, temperature 18.5°C, slight wind, no dew / Visual limiting magnitude 5.8 mag, seeing 3-4" FWHM, temperature 6°C, slight wind, no dew / Visual limiting magnitude 6.0 mag, seeing 2" FWHM, temperature 11.5°C, no wind, no dew
Autoguider: Meade Pictor 216 XT, max. error: 3" (RA) / 2" (Dec); 1" (RA) / 1" (Dec); 1" (RA) / 1" (Dec)
Enhancement: Basic data reduction, combine, logarithmic curves, background flattening, color correction, noise filtering, star size reduction, dynamic range extension, local contrast enhancement
Remarks: It has been a long hunt for exposures of this galaxy. During all three nights the exposure series were cut short by incoming clouds.

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