NGC 55. Caldwell 72

ngc55-slrgb-2c7-final4-bc

Click on the image for a larger version

NGC 55 is a galaxy that has been traditionally linked to the Sculptor Group, and it still is considered so in most web sites that you can browse currently. This group is close to our Local Group and has several large and well known galaxies, like NGC 253, the Silver Dollar Galaxy. But in 2003, Karachentsev et al. determined the distance to be too short for NGC 55 to belong to this group. This was confirmed in 2006, by van de Steene et al. by measuring the luminosity of planetary nebulae within it. Now, it is considered that it forms a gravitational pair with its close neighbor, NGC 300, and that they are located between the Sculptor and the Local Group. Their recession speed (around 130 km/s) also advocated for these galaxies not belonging the Sculptor group. NGC 55 is considered to be an SBm galaxy, a medium- to low sized barred Magellanic spiral galaxy.

 

Additional Information

Object

Name(s): NGC 55. Caldwell 72

Type: SBm, barred Magellanic spiral galaxy.

RA:  00h 15m 07s

Dec: -39º 13’ 16”

Constellation: Sculptor

Size (arcmin):32×6

Magnitude: +7.9

Distance: 6.9 Mly

Image

Date: 2016-08-28+29

Location: iTelescope.net, SSO near Coonabarabran, NSW Australia

Size (arcmin):36×27

Telescope: Planewave CDK 20” f/6.8

Camera: SBIG STX16803 (4096x4096pix)

Guiding: Astrodon MonsterMOAG off-axis guider

Total exposure: 9 hours (L: 3h45m; RGB: 5h45m)

Processing: CCDStack, Photoshop CC 2015.5

 

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