M42 – Now with extra Hydrogen-alpha!

Last night it was clear so I went out with my telescope for the first time in ages. It should have marked two firsts:

  1. First successful use of autoguiding and remote control of telescope & camera via laptop
  2. First field use of my CLS-CCD filter

Unfortunately, the autoguiding failed spectacularly after the laptop decided that the product key I had previously entered was no longer OK, and refused to co-operate. There was no 3G signal at all at my dark site, so with the laptop out of action and no prospect of remote control, I controlled the camera by hand (it was cold and I got numb fingers).

On the plus side, I achieved the first proper use of my CLS-CCD filter with a full-spectrum DSLR. It serves a dual purpose of allowing a lot more hydrogen-alpha radiation through and cutting down on the amount of orange sodium light pollution that is still visible in the sky an hour’s drive away from Bristol.

The CLS-CCD filter let through so much extra radiation compared to a non-modified DSLR that my “usual” exposure settings for astrophotography massively overexposed M42, the Orion nebula. Eventually I found that 25 seconds at ISO 3200 did a nice job, and I rattled off a few frames

This picture is the result of 19 frames and 4 dark frames stacked with DeepSkyStacker. When I have the autoguider working, I’ll be able to expose for longer without motion blur and will be able to reduce the ISO (and the noise) even further.

M42 Orion nebula
M42 Orion nebula

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