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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.

519CADE2-5B93-46F1-8A6A-7CBAA8C4CFB1.thumb.jpeg.9de68384692af031aad4cb91347b55b2.jpeg

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.

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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 )”

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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

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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 : 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
===============================================

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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 Galaxy
Silver Coin Galaxy
Silver Dollar Galaxy

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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 )

 

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Edited by MikeODay
I replaced the images in this post - for some reason either iTunes or my Ipad compressed the images when they were transferred from my PC. These versions I transferred via Dropbox and they are significantly sharper and higher contrast!
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I just edited the original post to replace the images.  

I could not understand why they were so soft and low contrast - I assumed it was just the site compressing the smaller images that are shown in the post but when I clicked on them even the larger images were poor quality.  It turned out that for some reason either iTunes or my Ipad compressed the images when they were transferred from my PC.  

The new versions I transferred via Dropbox and they are significantly sharper and higher contrast!

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23 hours ago, MikeODay said:

I just edited the original post to replace the images.  

I could not understand why they were so soft and low contrast - I assumed it was just the site compressing the smaller images that are shown in the post but when I clicked on them even the larger images were poor quality.  It turned out that for some reason either iTunes or my Ipad compressed the images when they were transferred from my PC.  

The new versions I transferred via Dropbox and they are significantly sharper and higher contrast!

Interesting.. I was using my ipad to look at the originals & they didn't look soft.. not compared to other posts on here I'd browsed same time. Now I look at these on a proper monitor I see it looks smoother & background's not as dark. If anything the processing looks a lot more smoother & natural.. even better :)

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On 09/10/2017 at 22:46, Sp@ce_d said:

Interesting.. I was using my ipad to look at the originals & they didn't look soft.. not compared to other posts on here I'd browsed same time. Now I look at these on a proper monitor I see it looks smoother & background's not as dark. If anything the processing looks a lot more smoother & natural.. even better :)

Thanks, much appreciated.

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This is the start of what one day will become an annotated star chart / star map of the Sculptor Galaxy and surrounding area.  It will provide a map to the numerous ‘small’ galaxies throughout the image.  For now it just has the grid produced by the image solver script in Pixinsight.

B3785095-72FC-4624-A562-8857334F3DCA.thumb.jpeg.8ebe9e459cb06a5b1390692becd65f79.jpeg

Sculptor Galaxy - NGC 253 - Star Map / Star Chart ( Epoch: 2017.9.23 )

( please click / tap on image to see medium size and tap again to see larger still )

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And a crop focusing on the Sculptor Galaxy and immediate surrounds ...

225E1EEF-5A07-4605-BE60-45BD79C8263B.thumb.jpeg.f77e0c66886efc809db80181f42b7adf.jpeg

Crop:  the top face ot the spiral Sculptor Galaxy ( NGC 253 ) swirling in a clock-wise direction with the bottom-left edge in the foreground closest to the observer and the wispy ends of the spiral arms at the top-right further off in the distance.

Edited by MikeODay
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Why is South up in your Star Chart ?

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From down here under the equator, when one turns and faces the sun, the North Pole is in front but down below the horizon, the South Pole is high in the sky behind one’s back and the Sun rises in the east off to the right.   Hence the directions noted in the Star Chart above:  North at the bottom, South up at the top and East off to the right.  

In other words, the Star Chart reflects the way the sky is presented to a Southern Hemisphere observer who is facing towards the north and looking up at the Sculptor Galaxy.

Edited by MikeODay
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15 hours ago, Shibby said:

Incredible image with amazing fine details resolved. Who needs a CCD?

We'd never see a galaxy near the horizon these days; at least, not where I live!

Thank you Lewis, much appreciated.

I am lucky down here Sydney with a great many wonderful objects that are well placed for me but are not seen or are too low in the sky to image well from where most of you are up in the North.  The Sculptor galaxy in particular is really well placed for me and rises to over 80 deg in altitude.  Stil, I wish I could see the Andromeda Galaxy  - it never rises above the tree line behind my house :(

 

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19 hours ago, cletrac1922 said:

Mike

Amazing image from land down under

Why Pixinsight is becoming the main choice for image processing

cheers 

John

Thank you John, much appreciated.

How is the viewing from up there?  

I imagine you can see more; the whole of the south plus more of the north.  Although I suppose some parts of southern Queensland must suffer quite badly from humidity.

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