Telescope: Unitron 155 4” f/15 refractor, Atlas EQ-G
Camera: Canon EOS Ra full frame DSLR
Filter: 2” GSO IR Cut Filter
Guide scope: Orion 50mm Guidescope, ASI120MM, PHD, Dithered every 4 subs
Exposure: 10x240sec, ISO 1600, saved as RAW
Darks: Internal (Long Exposure Noise Reduction)
Flats: 32×1/10s sky flats taken at dusk
Average Light Pollution: Bortle 8, fair transparency
Lensed Sky Quality Meter: 18.5 mag/arc-sec^2
Stacking: Mean with a 1-sigma clip
White Balance: Nebulosity Automatic
Software: Backyard EOS, Deepsky Stacker, Nebulosity, Photoshop
This field needs more subs and better conditions, but since I am limited to imaging on the east side of the meridian that will have to wait until next year.
M51 is a beautiful face-on spiral galaxy in Canes Venatici, just south of Alkaid, the bright star that lies at the eastern end of the Big Dipper. The spiral arm that appears to connect M51 to the nearby companion (NGC 5195) is a bit of an illusion. The companion actually lies behind M51, and if you look closely you can see that the spiral arm is silhouetted against the background galaxy. Modern observations and computer modeling suggest that the companion has made at least two passes through the main disk of M51. During the first, it approached M51 from behind, passed through the face of the galaxy, swung around in an orbit that took it in front, and then back through the disk where it lies now behind M51. These passes set off bursts of star formation that gives the arms of M51 their beautiful blue color.
M51 is currently well placed high in the northeast during the early evening.
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