Globular cluster M3 in Canes Venatici

Further tuning & testing my setup, I used some clear sky to image this globular cluster in Canes Venatici. 31x180s on ISO800 with the regular setup: C11 D750 Optolong, ASI174MM

I tried out an alternative way to collimate before imaging, by attaching the ASI camera on a Nikon T-Ring adapter. This way the whole image train is kept in place and only the camera’s are switching.

It did not work out as expected, so have to find a way to collimate using the Nikon instead. Challenging!

Anyhow as a result the full frame image was not flat / in focus so I needed to drop this image. The size was reduced to 70% with a pixelscale of 0,8″ per pixel and field diameter of 20′

This globular is at a distance of 34.000 light years and contains approximately half a million stars (I expected more to be honest). Surprisingly it moves towards us at a speed of 147 km/s. 5source: messier-objects.com)

(click on the image for a larger version)