Rosette Nebula (Caldwell 49)


The Rosette is a large area of hydrogen in the Monoceros region. This is a 2×1 mosaic of H-alpha (red) and O-3 (green & blue) exposures because the target is so big that it doesn’t fit in one frame – even with my fairly short telescope.

I had intended to add some RGB data to this image, but that will have to wait until I can get to a dark sky site. Or at least until near the new moon! This version is just H-alpha for red and O-3 for green and blue.

Scope: AT111EDT at f/5.6
Mount: AP Mach1
Camera: QSI 583 at –25C
Exposure: 15 x 480s H-a, 15 X 480s O-3 (2x each for mosaic) (8 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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