Re: NGC 247 – Interesting void within an intermediate spiral Galaxy


Gregg Ruppel
 

Excellent rendition Terry.  Your extended integration times were well worth the effort.  Thanks for sharing and the accompanying details.

Gregg

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On Dec 21, 2017, at 2:47 AM, terry.robison@... [ap-gto] <ap-gto@...> wrote:

 

NGC 247 – Interesting void within an intermediate spiral Galaxy


NGC 247 is an intermediate spiral Galaxy located in the constellation Cetus. It is a member of the sculptor group and is located approximately 11.1 million light years away. The most striking feature of this Galaxy, the void, contain stars that are different from those around. They are older, redder and colour, and much fainter. This suggests that the star formation within the void has been arrested. It is believed that star formation slowed a billion years ago.  We are still unsure how the void has formed.  Recent studies suggest it might have been caused by gravitational interactions with another galaxy, or even a recent interaction with a nearly dark subhalo that collided with the disc. 


The centre of the Galaxy is visible as a bright whitish patch surrounded by mixture of stars, gas, and dust.  Silhouetted against the background of stars the dust and gas has formed interesting filaments.


The best month for viewing NGC 247 is in November when it is at its highest altitude.  It has an apparent magnitude of 9.9, and an apparent size of 21'.4 × 6'.9.  NGC247 is also known as ESO 540-22, C 62, IRAS 00446-2101, MCG -4-3-5, PGC 2758, UGCA 11.


https://www.flickr.com/photos/97807083@N00/24330831247/


Image Details

Center (RA, hms): 00h 47m 19.577s

Center (Dec, dms): -20° 43' 59.305"

Size:                 47.8 x 31.8 arcmin

Radius:                 0.478 deg

Pixel scale:         0.804 arcsec/pixel

Orientation:         Up is 118 degrees E of N


Instruments:

10 Inch RCOS fl 9.1

Astro Physics AP-900 Mount

SBIG STL 11000m

FLI Filter Wheel

Astrodon Lum, Red, Green, Blue Filters

Baader Planetarium H-alpha 7nm Narrowband-Filter


Exposure Details:

37 X 900 Bin 1X1 Lum

21 X 450 Bin 2X2 Red

21 X 450 Bin 2X2 Green

22 X 450 Bin 2X2 Blue

13 X 900 Bin 1X1 Ha


Total time: 20.5 hours


Location

Australia, Central Victoria

Imaged from May-June 2017


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