California Nebula


California Nebula

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Sectional prints are available in dimensions that are multiples of 20cm (about 8 inches). The following sizes and prices are for example only. Please select the desired width below to get a quotation.

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80x60cm $90
120x80cm $140
160x120cm $210

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This nebula contains all 3 of the target spectral lines, hydrogen-alpha, sulphur-2, and oxygen-3. But I didn’t get enough OIII data to do anything other than balance the color of the stars. I was using 8 minute sub-exposures because that’s where bright stars were starting to saturate, but I think I would need to go to longer subs to get any OIII nebulosity. The SII image has significant nebulosity, but not a lot of differentiation from the H-a image, so longer subs would probably help there as well.

This is a 2×1 mosaic and, unusually, doubles the longer axis. Not many targets are as elongated as the California Nebula.

The channel assignments are R=H-a, G=SII, B=OIII. However, I tweaked the hue slightly after combining the channels because this shows the difference between H-a and SII more clearly.

Guiding was excellent most of the time, but the wind seemed to affect it at times.

Scope: AT111EDT at f/5.6
Mount: AP Mach1
Camera: QSI 583 at –25C
Exposure: 10 x 480s H-a, 10 x 480s S-2, 6 X 480s O-3 (2x each for mosaic) (7 hrs total)


About Greg Marshall

I am a retired electronics engineer and after a few months of enjoying my leisure I began to miss doing product development. My astronomy hobby always needed new solutions to unique problems, so I decided that whenever I came up with a good solution I would try to make it available to others.

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