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A new High Dynamic Range image of the Sculptor Galaxy ( NGC 253 ) captured over a number of nights in mid-September 2017 and processed with PixInsight using the DrizzleIntegration and PhotometricColorCalibration tools. The Silver Coin or Sculptor Galaxy ( NGC 253 ) in the Sculptor constellation. ( please click / tap on image to see larger and sharper ) On the 23rd of September 1783, sitting before her telescope in the field behind the house she shared with her brother William at Datchet, near Slough in the south of England, Miss Caroline Herschel "swept" the sky searching for new comets and never before seen star clusters and nebulae. On this occasion, way down in the sky, not far above the Southern horizon, in an area of the southern sky that Nicolas de Lacaille had called the “Apparatus Sculptoris” or “the sculptor’s studio", Miss Herschel saw and noted down a very bright and large nebula where one had never before been recorded. This event was later recognised by her brother, Sir William Herschel, as the discovery, by Caroline Herschel, of the nebula he listed in his catalogue as H V.1. In later years, her 'beloved nephew', Sir John Herschel, William's son, would record this 'nebula' as entry # 138 in his General Catalogue of Nebulae and Clusters of Stars ( eventually becoming the 253th entry in the New General Catalogue, NGC 253 ). Whilst relatively close to us compared to the billions of far more distant galaxies in the Universe, the great size of the “Sculptor Galaxy” and the huge distances involved are still hard to comprehend. To put this into some perspective, the light that is just now reaching one edge of the great disc left the opposite edge when the Earth was in the grip of last great Ice Age 70,000 years ago and the light we now see has been travelling towards us for over 11 million years. ........ More information on the discovery of the Sculptor Galaxy by Miss Caroline Herschel, as well as the later observations by both Sir William and Sir John Herschel, can be found in my Stargazerslounge blog, “The Sculptor Galaxy ( NGC 253 )” ......... This image was captured over a number of nights in the middle of September 2017 and processed on the 23rd; exactly 234 years from the day of its discovery by Caroline Herschel. With over 18 hours of total exposure, this HDR image attempts to capture the huge range of brightness levels; from the brightest stars and the core of the galaxy through to the numerous 'tiny' galaxies scattered throughout the image ( the total magnitude range is from around mag 8.8, for the brightest star, to 22+ for the faintest stars and galaxies visible in the image). Mike O'Day ...................... Capture Details: 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 ( 16, 17, 19,20,22 Sept. 2017 ) 8 sets of sub-images with exposure duration for each set doubling ( 2s to 240s ) all at ISO800 273 x 240s + 10 each @ 2s to 120s total around 18hrs Processing Calibration: master bias, master flat and no darks. Drizzle Integration in 8 sets. HDR combination PhotometricColorCalibration Pixinsight & Photoshop 23 Sept. & 8 Oct 2017 Image Plate Solution ( this cropped image ) =============================================== Resolution ........ 1.324 arcsec/px Rotation .......... -180.00 deg ( South ^, East > ) Field of view ..... 57' 57.5" x 38' 40.1" Image center ...... RA: 00 47 32.809 Dec: -25 17 04.48 =============================================== .................... Designations and alternative names for the Sculptor Galaxy: CH10 ( Caroline Herschel # 10 ) H V.1 ( William Herschel, Class V ( very large Nebulae ) # 1 ) H 61, H 2345 ( John Herschel observations identifiers ) GC 138. ( John Herschel’s - A General Catalogue of Nebulae and Clusters of Stars # 138 ) NGC 253 ( John Herschel’s catalogue updated by Dreyer - The New General Catalogue of Nebulae and Clusters of Stars # 253 ) Caldwell 65 Leda 2789 ESO 479-29 Sculptor GalaxySilver Coin GalaxySilver Dollar Galaxy .................. Annotated image of the Sculptor Galaxy ( NGC 253 ) - showing the brighter stars ( from the Tycho-2 catalogue ) as well the galaxies recorded in the Principal Galaxies Catalogue ( PGC ). I have yet to complete identifying and annotating the very large number of ‘tiny’ galaxies in the image. ( please click / tap on image to see larger and sharper ) .........