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“The Blue Bunny Nebula” .......... Edit: 27 Jan 2018 - updated again to try to draw more faint nebulosity out of the background; ( NGC 2359 - Thor’s Helmet ) ( please click / tap on image to see larger and without compression artefacts ( and double click on that image if you what to see it as I posted it ! ) ) ......... Edit: 24 Jan 2018 - stars a little brighter and tighter with no change to the rest of the image ( NGC 2359 - Thor’s Helmet ) ( please click / tap on image to see larger and without compression artefacts ( and double click on that image if you what to see it as I posted it ! ) ) ................. original: Thor's Helmet ( NGC 2359 ) in the constellation Canis Major Thor’s Helmet ( Duck Nebula, NGC 2359 ) ( please click / tap on image to see larger ) This HDR image shows the bright nebula Thor’s Helmet 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 around +20 or more. 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 their "true colours" by 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. Image details: NGC 2359 Thor’s Helmet / Duck Nebula: Magnitude +11.5, RA (2000.0) 7h 15m 37s, Dec -13deg 12' 8", approx. 1800 light years away HD 56925 / Wolf-Rayet 7 ( WR7 ) ( blue 11.5 mag star at centre of “bubble” ) Haffner 6 ( open ster 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
Thor’s Helmet ( NGC 2359 ) ( NGC 2359 - Thor’s Helmet ) ( please click / tap on image to see larger and without compression artefacts ( and double click on that image if you what to see it as I posted it ! ) ) Summary: An HDR image that captures as much of the faint detail in the nebula as I can whilst also attempting to show the “true” colours of the stars ( without burnt out highlights ). Nikon D5300 ( unmodified ), taken 18/19 Jan 2018, exposures ranging from 2s to 240s ( 116 x 240 sec + 5 each for other exposures ) Full details in main post :