Object info

Discovered in 1773, M51 (& NGC5195) is one of the most well known galaxies in the sky and is a good example of a face-on spiral galaxy. Its distance is 37 million light years. Just as M81 and M82, M51 and NGC 5195 (bottom part) are also gravitationally interacting galaxies. Sometimes M51 is used to refer to both galaxies, in which case the individual galaxies are referred to as M51A (NGC5194) and M51B (NGC5195).

Processing

CCDOPS was used for focussing. Image Acquisition was done using CCDSOft.
All separate frames were calibrated, aligned and stacked in ImagesPlus 2.8.
Photoshop CS2 was used for further processing - curves adjustment, levels adjustment, etc. The image was calibrated using 9 darks, 25 (dark-subtracted) median combined flats and 6 bias frames.

Comments

Both collimation and focus is off.

Previous versions

Mar 12, 2007 - 1024 x 768 Pixel (142 kB)
Optics : GSO 8" f4 Newton, MPCC + Baader Moon & Skyglow
Mount : Losmandy G-11 + Canon 350D
Exposure : 30 x 180 sec @ ISO800 = 1h 30m