A quick view of the Rosetta nebula

I didn’t want to miss getting a nice image of one of my all-time favourite nebulae, the Rosetta nebula, before it was too late in the season and moved into the west.

This image combines 15 x 60s exposures in each color channel, using broad-band filters B (blue), G (green) and R (red). I also tried to achieve natural colours (i.e. the colours we would see with our eyes).

The data were taken at 10:30pm, Sunday 15 March 2021, from Siding Spring Observatory (near Coonabarabran, NSW, Australia).

I used a ZWO ASI1600MM-Pro with the ZWO 2″ BGR filters, my new 7×2″ ZWO filter wheel, a Skywatcher Black Diamond 80mm with an Orion x0.8 focal reducer (effective focal length 480 mm, f/6). I used the ZWO ASIAir to control the camera, filter wheel, the mount (Skywatcher AZ-EQ6) and the guiding system (ASI120MM + Orion 50mm finderscope *).

The data have been processed with SIRIL, then converted into TIF using Fits Liberator using a logarithmic stretch, and finally combined in Photoshop to get the colours and the final details. Darks, flats and biases were used.

I usually try to get at least 30-40 frames per filter, but as I said this was a compromise to get a nice colour shot of this nebulae before it set, and hence I took 15 exposures per filter, and only 60 seconds (and the highest gain in the camera, hence the noise that can be seen when zooming in). Otherwise I would have taken ~5 minute exposures with a lower gain and 40 of them.

In any case, I hope you like it.

Credit: Ángel R. López-Sánchez (AAO-MQ).

Full resolution available in My Flickr.

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