The Rosette Nebula

The centre of the Rosette is the birthplace a star cluster now just a few million years old, whose strong stellar winds have carved out the “hole” in the nebula. The Rosette is also known as Caldwell 49, and the central stars are NGC 2244.


Version 3, reprocessed December 2022

Not a huge difference, but tighter stars and higher image quality when zoomed in.

A crop of version 2 on the left, and version 3 on the right.

Version 2, reprocessed June 2021

For this reprocess I used PixInsight’s SubframeSelector function to examine the quality of the source data from version 1 (15 hours). I was overly lenient originally — maybe too keen to get the total integration time up at the cost of subframe quality. For this version I cut anything that didn’t have a good FWHM or Stars rating. That axed six whole hours of data, leaving 270 x 120 seconds (9 hours). Combined with more careful editing, the resulting image is a lot sharper and contains more detail. It’s a definite improvement over the original.

Version 1 and 2 compared.

Version 1, February 2021

This was a fun target to image because there’s so much detail to bring out. I was too heavy-handed with the noise reduction in this version, but the dark dust lanes still look impressive.

* February 2021
* Bristol, UK (Bortle 8)
* Telescope: Askar FRA400 f/5.6 Quintuplet APO Astrograph
* Camera: ZWO ASI 2600MC-PRO
* Filter: Optolong L-eXtreme
* Mount: Orion Sirius EQ-G
* Guide: William Optics 32mm; ZWO ASI 120MM Mini
* Software: PixInsight, Photoshop, Lightroom, Topaz DeNoise AI
* Control: ASIAIR PRO
* 450 x 120 seconds

Total integration time: 15 hours

By Lee Pullen

Example source data

This is what a single 120-second subframe looks like, debayered and with a simple stretch.
This is the integration of 450 x 120 seconds (15 hours) just with a simple stretch, before any proper editing.


Spare a penny, guv’nor?





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