imaging challenge 9 rgb The Rosette Nebula and Star Cluster ( NGC 2237 and 2244 ) in the constellation Monoceros

[MikeODay]

( please click / tap to see larger )

Identification:

The Rosette Nebula ( NGC 2237 ) is a large, circular emission nebula in the constellation Monoceros. It surrounds a cluster of hot, young stars known as the Rosette Cluster ( NGC 2244 ). ( SkySafari )

NGC 2237, 2244

Caldwell 49, 50

North is up.

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Capture Details:

Telescope: Orion Optics CT12 Newtonian ( mirror 300mm, fl 1200mm, f4 ).
Corrector: ASA 2" Coma Corrector Quattro 1.175x.
Effective Focal Length / Aperture : 1400mm f4.7

Mount: Skywatcher EQ8

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

Camera:   Nikon D7500 (unmodified) (sensor 23.5 x 15.7mm, 5568x3712 @ 4.196um pixels)

Location:   

Blue Mountains, Australia 
Moderate light pollution ( pale green zone on darksitefinder.com map )

Capture ( 23 Dec 2017 )

9 sets of sub-images with exposure duration for each set doubling ( 1s to 240s ) all at ISO400.
10 x 240s + 5 each @ 1s to 120s
imaged ~ +/- 1.5hrs either side of meridian
maximum altitude ~ 51.3 deg above north horizon

Processing ( Pixinsight )
Calibration: master bias, master flat and in-camera dark subtraction
Integration in 9 sets
HDR combination 

Image Plate Solution
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Resolution ........ 0.633 arcsec/px ( full size image )
Rotation .......... 0.181 deg
Focal ............. 1367.90 mm
Pixel size ........ 4.20 um
Field of view ..... 58' 59.4" x 39' 15.0"
Image center ...... RA: 06 31 55.638 Dec: +04 56 30.84

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