M51

[frugal]

Like so many other people on here, I was taking advantage of the clear night on Saturday to get some imaging done. M51 was nice and high in the sky, so I thought I would have a go as I had never tried this particular galaxy before. After a while the guiding was fairly stable (not brilliant, but stable), and there was space on the histogram, so I changed from 5 min subs to 10 min subs in the hope of getting some more faint detail out.

The focus was spot on according to the Bahtinov mask, so I am assuming my big soft stars are either seeing, or guiding wobbles. The RMS error for guiding was 0.88" pretty much constantly for the whole session. With the Camera / scope combination I am imaging at 1.74"/pixel, so that means that 3 std dev of guiding error (which is 99% of the distribution) is +- 2.64" which should cover a 3 pixel area (2.64"x2 / 1.74 = 3.03). However the image seems a lot softer than that.

M51 by frugal10191, on Flickr

Lights: 22 x 300s @ ISO800; 16 @ 600s ISO800

Darks: 112 x 300s

Bias: 492

Flats: 23 x 1/8s

Integration: Bayer Drizzle (Scale 2, Drop Shrink 1.0)

Mount: Skywatcher AZ-EQ6 GT

Imaging Telescope: Skywatcher ED80 DS-Pro with 0.85x FF/FR

Imaging Camera: Canon 60D (Unmodified)

Guiding Telescope: Skywatcher ST-80

Guiding Camera: Starlight Xpress Lodestar X2

Software: Sequence Generator Pro, PHD2, PixInsight