M101 – Pinwheel Galaxy (widefield)

A few weeks ago, I had very clear skies and I wanted to try some deep sky imaging using the Astronomik Deep Sky RGB filters. Unfortunately many of the DSO’s I wanted to image were too low down in the sky to image successfully. Hence I thought I would try imaging one of the not too small galaxies in widefield – the M101 Pinwheel Galaxy.Just to put things in perspective, I was using my Samyang 135mm F2 lens @ F2.0 to image this object. I used a Gain of 200 and 1 minute subs to capture the Luminance (Astronomik CLS-CCD filter), R, G & B images on my ZWO ASI178MM-cooled camera. I managed to capture 21 x R, 20 x B, 20 x G and 42 x Luminance frames for stacking – a total 103 mins of exposure @ F2.0.

I then used Pixinsight to calibrate, integrate and finally process all the above images together to form the final image. I have to say that it proved to be more challenging than processing coloured images, as the Luminance image had to be processed separately to the RGB image, before final combination. I spent about 10 days doing it again and again as I seemed to make mistakes which required me to start from scratch each time; but I did learn from this and feel more able to use Pixinsight now – although perhaps not to its maximum potential.

M101 with a two other smaller galaxies in view
M101 with two other smaller galaxies in view

I think I was really pushing the limit of my equipment as this galaxy is very small, but it did allow me to try processing with Pixinsight.