M-101 the Pinwheel Galaxy

click the image for a larger view, or HERE for the index
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Messier number 101, the Pinwheel Galaxy in the constellation Ursa Major. M 101 has five companion galaxies scattered over a few degrees of sky, one, ngc 5477, is visible in this image on the upper left quarter. A notable feature of M 101 is the large number of HII star forming regions that might have formed as a result of an earlier encounter with a passing galaxy... There are also a number of smaller galaxies, not related, in the background. My image with the ES ED127 and Canon DSLR probably only reaches magnitude 17 putting most of these in the blackness...

Telescope

Explore Scientific 127mm, f7.5, ED apo with carbon fiber tube. Mounted piggyback on a Meade LX200 classic 12-inch SCT

Camera

Canon XT/350d modified with Baader type 1 filter by Hap Griffin

Exposure

25 ten-minute sub-exposures at iso 800, captured RAW. I used iso 800 in an effort ot retain more range in star color.

Guiding

Modified 10 x 50 finder scope with Meade DSI pro I controlled by PHD Guiding form Stark Labs

Processing

Images acquired, calibrated, stacked, and color corrected in Nebulosity 3.0.1 from Stark Labs on February 22nd, 2012. Further processing in Photoshop CS3.