Crescent Nubula Region

NGC6888, Caldwell 27. Taken between 25th and 28th August 2021.

 

The Crescent Nebula gets its shape as a result of an ageing star losing mass extremely quickly. Such a star is called a Wolf Rayet star and this one which is at the centre of the nebula will probably go supernova. According to the Sky at Night magazine this violent and rapid ejection has produced a dense shell of scorching hot material that gives the nebula its shape, while the complex structures seen within the bubble are likely the result of stellar winds colliding and interacting with older material ejected by the star long ago.

 

H: - 85 x 180s (4.25 Hours)

O: - 85 x 180s (4.25 Hours)

Total Integration = 9 hours.

 

Flats taken with a PURElite CFPL22 Ultra-Thin LED Light Box. Darks and Dark Flats taken afterwards and kept for future.

 

Telescope: - Skywatcher 130PDS Newtonian. Flocked with the shiny parts painted matt black. Additional camping mat protection from dew. Focuser upgraded with a ZWO EAF (Electronic Auto Focuser)

 

Camera : - ZWO ASI294MM with a ZWO 1.25” Electronic Filter Wheel

 

Filters:- Baader Mark-III MPCC Coma Corrector. Baader 7nm Ha and 8.5nm OII narrowband.

 

Mount: - Skywatcher EQ6R.

 

Guiding: Skywatcher EvoGuide 50ED & ZWO ASI120MM-Mini.

 

Controlled by an ASIAir.

 

Processing Software: Stacked in Deep Sky Stacker and edited in Star Tools and Denoise AI.

 

Moon: Pretty much full.

 

Light Pollution and Location: - Bortle 7/8 in Davyhulme, Manchester. Different websites tell me different things about this. It all depends on the time of night and which way I am pointing.

 

Weather: - High pressure but sitting horribly to the northwest of the country dragging lots of bitty cloud down from the north. Not ideal but dry enough to get a few days’ work in.

 

Notes: This is my first astrophotography project of the year having become a father at the start leaving me no time to do anything but be tired.

 

I wanted to go mono but to also make life easier and quicker, so I have invested in an auto focuser and the specialist astrophotography computer ASIAir. This has done the trick, polar alignment is extremely easy and then the rest can be automated so long as the focus is close. I like the way the Asiair automatically moves the mount into position when polar aligning, SharpCap relied on me rotating the mount which could have been inaccurate. It’s been a learning curve, especially getting the flats right but its quite intuitive and I think I am just about there.

 

Trying to get the colour somewhere near what I wanted it has been challenging too. I reprocessed this image several times.

 

During the off months I did spend time on upgrading my 130PDS to be very close to an astrograph. I flocked the inside, painted the shiny parts matt black, added more dew protection with camping mat material and covered the light leakage in the focuser with blue tac. I also used a laser collimator which I combined with my collimation cap to get the collimation right. One day I might add a fan to the primary mirror.

 

I got lots of hours in on this but would be tempted to reduce this in future to get more photos.

Done