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Whirlpool Galaxy, M51


The Whirlpool Galaxy, Messier 51, in the constellation Canes Venatici. It is an interacting spiral galaxy that is approximately 23 million light years away from Earth.

I have imaged this galaxy many times in RGB and with OSC cameras. This time I wanted to take it up a notch by using the ZWO ASI2600mc-pro, more integration and a night of hydrogen alpha imaging to bring out the pink nebulosity. I have never added hydrogen alpha data to a galaxy, so this was a learning process and trial and error processing session. The image is composed of 10 hours of 180 second exposed images at gain zero. The camera has an IR coated window over the sensor, so I did not use an UV/IR filter, and I image in my backyard under Bortle 3 skies, so no light pollution filter was used with the OSC data. On the 4th night of imaging, I used a two inch Astronomik hydrogen alpha 12nm filter on the ASI2600mc-pro. I captured approximately 4 hours of hydrogen alpha data. I calibrated the lights with darks, flats and dark flats. I stacked the frames in Astro Pixel Processor which ran most the day.

OSC (Top) Hydrogen Alpha (Bottom)

I did my normal processing routine on them, except, I combined the hydrogen alpha with the OSC data while they were linear using the NBRGB Script in PixInSight.


Celestron 9.25” EdgeHD

Celestron 0.7x Reducer for EdgeHD scopes

Celestron CGEM DX mount

Astronomic 2” 12nm Hydrogen Alpha Filter for the Ha channel

ZWO ASI2600mc-pro Imaging Camera

ZWO ASI224mc Guide Camera

Svbony 60mm Guidescope 

ZWO ASIair Pro for image acquisition and gear control.

Annotated in

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