sculptor galaxy The Sculptor or Silver Coin Galaxy ( NGC 253 ) in the Sculptor Constellation

[MikeODay]

The Sculptor or Silver Coin Galaxy ( NGC 253 ) in the Sculptor constellation - re-processed from the original subs

The Sculptor Galaxay ( NGC 253 )            ( Please click / tap on image to see larger and sharper )

....................

The Silver Coin Galaxy ( NGC 253 ) in the Sculptor constellation ( aka the Silver Dollar or Sculptor Galaxy ).

Caroline Herschel in 1783 was the first to recordthis bright ‘nebula’ in an area of the southern sky that Nicolas de Lacaille had called the “Apparatus Sculptoris” or “the sculptor’s studio”.

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.

Details:

NGC 253 - "Silver Coin" or "Sculptor" galaxy.
Catalogue location:  RA 00 48 23, DEC -25 11 52.

From Image Solver:
Image centre:  RA 00 47 33.4   Dec. -25 17 11.1
Focal length:  1008.5 mm
Field of view:  1d 19' 2.2"   x   53' 0.3"
 
Skywatcher Quattro 10" f4 Newtonian telescope.
Skywatcher AZ Eq6 GT Mount.
Orion Short Tube 80mm guide scope & auto guider - PHD2.
Baader MPCC Mark 3 Coma Corrector & no filter.
Nikon D5300 (unmodified).
Field of view (deg) ~ 1.35 x 0.90.
20 x 180 sec ISO 800, long exp noise reduction on.
Pixinsight & Photoshop.

November 4, 2016

re-processed from original subs ( including Photometric Colour Calibration ) - September 9, 2017

...........

Details of Sculptor Galaxy from SkySafari for the 4th of November 2016 around 10pm local time

.............

Annotated version ( using Pixinsight ImageSolver and Annotation scripts )

Sculptor Galaxy ( NGC 253 ) - annotated

The cyan tags ( 35 or so ) relate to galaxies recorded in the Principal Galaxies Catalogue. 

The white tags are brighter stars as recorded in the Tycho-2 Catalogue.  The number beneath is the magnitude of the referenced star. 

..........

Link to previous version below ...

 

[gnomus]

Very nice.  A classy rendition.

[Mark at Beaufort]

Very nice Mike together with the other information.

[tooth_dr]

Was that really taken with a DSLR and only 20x3mins subs? It's fantastic 

[des anderson]

Great image for such a short exposures, you sky`s must be exceptinal . Des

[MarsG76]

Beautiful pic.

 

[MikeODay]

On 09/09/2017 at 19:11, gnomus said:

Very nice.  A classy rendition.

 

On 09/09/2017 at 19:29, Mark at Beaufort said:

Very nice Mike together with the other information.

 

21 hours ago, MarsG76 said:

Beautiful pic.

 

 

On 09/09/2017 at 19:36, tooth_dr said:

Was that really taken with a DSLR and only 20x3mins subs? It's fantastic 

 

23 hours ago, des anderson said:

Great image for such a short exposures, you sky`s must be exceptinal . Des

 

Thank you guys for your kind comments.

If the smoke from bush fire hazard reduction fires ever clears up here ( grrr ) I might get a chance to try and improve on it further in a month or so as this was taken with my older 10" scope and with in-camera dark subtraction turned on.  With my newer 12" Orion Optics scope, more subs with lower noise ( I eventually figured out that in-camera dark subtraction was adding more noise than it was taking away ) and HDR processing I hope to capture more colour in the stars and greater detail in the galaxy.

As for "exceptional skys", well, the distance from the worst of the city lights and the moderate altitude ( ~ 700m ) does help but I am still in the green zone so I fight constantly with colour distortion and loss of faint detail due to light pollution.  And I have given up over the last month or so due to the smoke from controlled fires that has blanketed Sydney and its surrounds.  Even when one can't see the smoke it still shows up in greatly increased light pollution.  Oh well, I know they think it will help to keep us safe so I will just have to wait until it gets too hot for them to risk lighting fires ...

By the way, here is a single sub ( in-camera, daylight white balanced, JPG version ) from the set taken last November that shows the fairly typical levels of green/orange light pollution that I have near zenith ( when there is no smoke of course ).

I know many ( most ? ) people suffer from far worse and with enough subs I can usually manage it ok.  The new Pixinsight PhotometricColorCalibration tool that I now use has greatly simplified the steps I go through to remove the colour cast and I think gives better results overall.

[MikeODay]

I am facinated by the large number of "tiny" galaxies shown in the image - most of which just look like stars to me

One small fuzzy that looks like an edge on spiral to me is just to the left of the 9th mag star, TYC6421-1856-1

It is not recorded in the Principal Galaxy Catalogue ( via Vizier.u-strasbg.fr ) so it is not annotated in the image above. 

When I went looking I found it recorded as an 18th magnitude galaxy in the 2df Galaxy Redshift Survey catalgue ( via VizieR.u-strasbg.fr ).

( Link to above page at Simbad.u-strasbog.fr )

[MarsG76]

1 hour ago, mike005 said:

 

 

 

 

 

Thank you guys for your kind comments.

If the smoke from bush fire hazard reduction fires ever clears up here ( grrr ) I might get a chance to try and improve on it further in a month or so as this was taken with my older 10" scope and with in-camera dark subtraction turned on.  With my newer 12" Orion Optics scope, more subs with lower noise ( I eventually figured out that in-camera dark subtraction was adding more noise than it was taking away ) and HDR processing I hope to capture more colour in the stars and greater detail in the galaxy.

As for "exceptional skys", well, the distance from the worst of the city lights and the moderate altitude ( ~ 700m ) does help but I am still in the green zone so I fight constantly with colour distortion and loss of faint detail due to light pollution.  And I have given up over the last month or so due to the smoke from controlled fires that has blanketed Sydney and its surrounds.  Even when one can't see the smoke it still shows up in greatly increased light pollution.  Oh well, I know they think it will help to keep us safe so I will just have to wait until it gets too hot for them to risk lighting fires ...

By the way, here is a single sub from the set taken last November that shows the fairly typical levels of green/orange light pollution that I have near zenith ( when there is no smoke of course ).

I know many ( most ? ) people suffer from far worse and with enough subs I can usually manage it ok.  The new Pixinsight PhotometricColorCalibration tool that I now use has greatly simplified the steps I go through to remove the colour cast and I think gives better results overall.

I have the hazard reduction burning around my area too... but I'd say generally you have very dark skies in the blue mountains area, similar too mine is imagine.

As far as dark subtraction in the DSLR, I find it a waste of time since when I import the CR2 files into camera raw in PS, the application does a very good job in removing noise, and only noise... than stacking takes care of the rest... now that you mention that it adds more noise than that's another reason to use that time that generates the darks to get more light frames.

Nontheless, even with the hazard reduction, LP and internal darks, that image is fantastic.

[MarsG76]

1 hour ago, mike005 said:

fairly typical levels of green/orange light pollution

This does look very typical and similar to what I get through my 40D at ISO 400 in 400-500s subs on a good dark night.

[MikeODay]

14 minutes ago, MarsG76 said:

I have the hazard reduction burning around my area too... but I'd say generally you have very dark skies in the blue mountains area, similar too mine is imagine.

As far as dark subtraction in the DSLR, I find it a waste of time since when I import the CR2 files into camera raw in PS, the application does a very good job in removing noise, and only noise... than stacking takes care of the rest... now that you mention that it adds more noise than that's another reason to use that time that generates the darks to get more light frames.

Nontheless, even with the hazard reduction, LP and internal darks, that image is fantastic.

It took my a couple of years to understand that dark subtraction is only useful for the removal of pattern noise and hot pixels and actually makes random noise worse.  As my camera has no discernible pattern noise and few hot pixels, I have stopped using darks ( in-camera  or otherwise ) and my images have improved.

Cheers

Mike

[MikeODay]

19 minutes ago, MarsG76 said:

This does look very typical and similar to what I get through my 40D at ISO 400 in 400-500s subs on a good dark night.

It is not too bad but I would love to live somewhere with truely dark skies - we may move to NZ when I retire; it's a pity Lake Tekapo is so remote otherwise there would be ideal for me.

[MarsG76]

1 hour ago, mike005 said:

It took my a couple of years to understand that dark subtraction is only useful for the removal of pattern noise and hot pixels and actually makes random noise worse.  As my camera has no discernible pattern noise and few hot pixels, I have stopped using darks ( in-camera  or otherwise ) and my images have improved.

Cheers

Mike

same....

 

[MarsG76]

1 hour ago, mike005 said:

It is not too bad but I would love to live somewhere with truely dark skies - we may move to NZ when I retire; it's a pity Lake Tekapo is so remote otherwise there would be ideal for me.

What about that air field just past Katoomba.... apparently there is mag 6 visibility....

[MikeODay]

I'm not that far from Katoomba, over 100kms from the Sydney CBD.  According to darksitefinder.com I'm in the border area between bright green and the next category ( I don't know what the colour is called; "dark-yellow" maybe ( ? ) )

One has to be way out past Parkes to finally be free from the greater Sydney glow.  

Apparently even the observatories near Coonabarabran are starting to be impacted by the lights from the Sydney / Newcastle region.

 

[MikeODay]

Scrapbook page ...

The Sculptor or Silver Coin Galaxy ( NGC 253 ) in the Sculptor Constellation - Scrapbook page

( please click/tap on image to see larger )

[MikeODay]

Sculptor Galaxy, Lick Observatory, glass plate1902.   

Made with the 3 foot Crossley Reflector

From the book "Photographs of Nebulae and Clusters, made with the Crossley Reflector, by James Edward Keeler, Director of the Lick Observatory. 1989-1900."

The ebook can be downloaded for free from :  http://www.gutenberg.org/ebooks/36470

This image is plate 2 in the book and was a three hour exposure, during which
“...observer and assistant exchange places every half hour, thereby greatly relieving the tediousness of the work..."