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The Sculptor Galaxy, also known as the Silver Coin or Silver Dollar Galaxy, NGC 253, an intermediate, starburst spiral galaxy in the constellation Sculptor, about 11.4 million LY away, undergoing a period of intense star formation.
This photo was imaged in natural color through my 8" Celestron SCT at 2032mm focal length using my astro-modded and cooled canon 40D DSLR and tracked with a CGEM mount.
I imaged this galaxy when the moon was nearly at first quarter and in the same general direction as the galaxy, so I used the Neodymium filter (AKA Moon and Skyglow filter) instead of the UV/IR Cut filter to try and control the moon glare, I think it worked.
Total exposure time was 5 hours 41 minutes.
I finally got around to get myself a 8" f/5 Newtonian with a GSO coma corrector and had my first go at the Sculptor galaxy (NGC253). The picture was taken from 33 frames, 180sec at ISO800. First off, I was impressed with how much light the scope collects compared to the ED80. I could already see the dust lanes on the individual frames. I noticed that I still had coma in the corners of the full image and searching the internet found that the coma corrector requires a 15-20mm spacer to work with DSLRs - Bummer! The stars are wider than what I am used to. According to the Bhatinov mask, focus should have been pretty spot on but compared to the ED80 my star width went from 3.6 to 5.6 pixels. Is this due to the missing spacer ring, still not perfect focus or that my mount (HEQ5) is struggling with the weight, or do I have to live with it? Just trying to understand what is normal for a reflector and what I can improve.
Thanks in advance and clear skies!
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).
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
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
Calibration: master bias, master flat and no darks.
Drizzle Integration in 8 sets.
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 )
Silver Coin Galaxy
Silver 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 )