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Thor's Helmet ( NGC2359 ) in the constellation Canis Major - by Mike O'Day ( 500px.com/MikeODay ) - updated version 27 Jan 2018

Thor's Helmet ( NGC 2359 ) in the constellation Canis Major

 

This HDR image shows the bright nebula in a sea of colourful stars against a background of red from dust and HA emissions. The stars in this image range from the brightest ( bottom right, HD 56501 ) at magnitude +7.7 to more than +22. HDR capture and processing allows all of the stars to be portrayed in colour without any burnt-out highlights. The colours of the stars and nebula are as close as I can get them to the "true colours" using a "daylight colour balance" and allowing for the extinction of blue-green due to atmospheric absorption/scattering ( mean altitude during capture ~ 60deg ).

 

The blue star in the centre of the bubble of expanding stellar material is HD 56925 ( WR7 ) - a massive, unstable and short-lived Wolf-Rayet star that one day will detonate in a supernova.

 

Magnitude +11.5, RA (2000.0) 7h 15m 37s, Dec -13deg 12' 8"

Approx. 1800 light years away

 

Image details:

 

Alt. Title: " The Blue Bunny Nebula "

NGC 2359 Thor's Helmet

aka The Duck Nebula

 

Wolf-Rayet star #7 - HD 56925

( 11.5 mag blue star at the centre of the 'bubble' )

 

Haffner 6 - Open Star Cluster

( centre left of image )

 

Plate Solution:

Resolution ........ 1.318 arcsec/px

Rotation .......... 0.00 deg ( North is up )

Focal ............. 1398.41 mm

Field of view ..... 57' 40.8" x 38' 29.0"

Image center ...... RA: 07 18 36.509 Dec: -13 11 53.38

 

Telescope: Orion Optics CT12 Newtonian ( mirror 300mm, fl 1200mm, f4 ).

Corrector: ASA 2" Coma Corrector Quattro 1.175x.

Effective Focal Length / Aperture : 1410mm f4.7

 

Mount: Skywatcher EQ8

Guiding: TSOAG9 Off-Axis-Guider, Starlight Xpress Lodestar X2, PHD2

 

Camera:

Nikon D5300 (unmodified) (sensor 23.5 x 15.6mm, 6016x4016 3.9um pixels)

 

Location:

Blue Mountains, Australia

Moderate light pollution ( pale green zone on darksitefinder.com map )

 

Capture ( 18 & 19 Jan 2018 )

9 sets of sub-images with exposure duration for each set doubling ( 1s to 240s ) all at ISO 250.

116 x 240s + 5 each @ 1s to 120s

 

Processing ( Pixinsight - 20 Jan 18 )

Calibration: master bias, master dark and master flat

Integration in 9 sets

HDR combination

arcSinH stretch

 

Links:

500px.com/MikeODay

photo.net/photos/MikeODay

www.flickr.com/photos/mike-oday

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Uploaded on January 21, 2018