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NGC6357 SIIHaHb F6.3 24May-15Jun 2020


Sharing with you my latest image of NGC 6357 in the constellation Scorpius near the better known NGC 6334, AKA the "Cat's Paw" or "Bear Paw" nebula. This nebula was also given the name War and Peace Nebula because of its appearance in infrared images, the bright western part resembles a dove and the eastern part looks like a skull. This photo was taken through my Celestron 8" SCT at f6.3 (1280mm focal length), tracked on a CGEM and exposed using my full spectrum modded and cooled Canon 40D DSLR. This image was a bit of an experiment to see how much improvement in noise and sensitivity will be in my long exposed subs after I redesigned the cooling system on my DSLR.. now the sensor temperature was kept at freezing point. When uncooled the sensor temperature was around 27°-32°C and the first version of the cooling system only cooled and kept the sensor temperature at +/- 1°C of ambience... now with the redesigned cooler, I had the temperature drop to -5°C (from 18°C ambient temp) during test and set the controller to stop cooling at 0°C and start cooling at 1°C when imaging this object.  The improvement in subs was substantial, 1800 second ISO1600 subs had almost no noise, only few pure white single pixels of noise within the subs, easily removed with single pixel noise reduction, so I'm more than happy with how my 40D is cooled and the subs it's delivering. This image consists of only my SII and HAlpha subs so it is still a work in progress as I still need to expose the OIII subs to add to the SII and HAlpha frames. The was I assembled the channels was by using the red channel in SII as RED, red channel in HAlpha as GREEN and a added combination of the faint signal captured in both blue channels of SII and HAlpha (Hbeta signal) as BLUE.


© Mariusz Goralski

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