M27 Collaboration

Image Description and Details : 3 astrophotographers' collaboration on M27 :

Halpha and Oiii long exposures with Newton 10" and ASI2600mm : 224 x 300s by Mathieu Guinot
Halpha and Oiii long exposures with RC16" and ASI2600mm : 200x300s by Sebastien Kuenlin
RVB long exposures with Newton 10" and ASI2600mm : 90x120s by Mathieu Guinot
Halpha lucky imaging with Newton 12"and Playerone Neptune color II : 5000x2.5s by Stephane Gonzalez
IR - RVB lucky imaging with Newton 12"and Playerone Neptune color II : 40000x500ms by Stephane Gonzalez

The processing of the M27 nebula always presents a certain difficulty and forces choices because of the great difference in luminosity between the core and the extensions on the one hand, and the strong presence of Halpha and Oiii signals on identical zones on the other hand.
These artistic choices have been made with maximum respect for the scientific coherence of the object, although this is not 100% possible: indeed, one obtains a saturated core if one wants to take advantage of the signal on the most distant extensions, or one does not distinguish these if one wants to maintain an unsaturated core. It is therefore necessary to use HDR processing as sparingly as possible, which inevitably alters the object's dynamic range but allows a compromise to highlight the different signals making up the nebula.

In the end we are very happy to present the fruit of this work with the objectives fulfilled:

- to enjoy the details of the short exposures
- to take advantage of the extensions of the long exposures
- to ensure coherence between the levels of detail thanks to the intermediate image taken in long exposure at long focal length
- keep the dynamics of the object as "real" as possible
- not to perceive any artefact or transition linked to the mixing of the three images


Sébastien, Stéphane and Mathieu, November 2021

Copyright: Stephane Gonzalez, Sébastien Kuenlin and Mathieu Guinot