Two Fine Galaxies in the Sculptor Group

Image of NGC 55 acquired by Brett Soames of NSW, Australia and processed by Warren Keller at www.billionsandbillions.com.

Image of galaxy NGC 55 acquired by Brett Soames of NSW, Australia and processed by Warren Keller at www.billionsandbillions.com.

One of the closest congregations of galaxies to our own, the Sculptor Group consists of a series of relatively bright and shapely galaxies clustered in the barren sky near the south galactic pole. The group is anchored by the majestic NGC 253, the Silver Coin Galaxy, one of the most beautiful galaxies for a small telescope. But a little farther south lie two more gems, NGC 55, also called the ‘String of Pearls’, and NGC 300, one of a handful of galaxies known as the ‘Southern Pinwheel’. For northern observers, this pair is low in the thick air over the southern horizon in the late months of the year. Southern-hemisphere observers, however, see these galaxies nearly overhead where it’s much easier to see their distinctive shape and features in a small telescope.

First to NGC 55. The galaxy is located near the southern edge of the constellation Sculptor near its border with the constellation Phoenix. The galaxy is about 3.7° northwest of the star Ankaa or α Phoenicis in Phoenix, and 2o west of a 5th magnitude orange star and a string of three 7th-magnitude stars that point right to the galaxy.

A rough sketch of NGC 55 made with a 10" f/4.7 Newtonian reflector at 65x.

A rough sketch of NGC 55 made with a 10″ f/4.7 Newtonian reflector at 65x.

While smaller and fainter than the more famous Silver Coin Galaxy, NGC 55 is in many ways a far more impressive sight in a small telescope.  At lowest power in a 4-inch or larger scope, the galaxy looks like a long graceful comet with a tail and anti-tail thrusting off a brighter and well-structured nucleus.  The long axis of the galaxy stretches nearly half a degree from the east-southeast to the west-northwest.  With your telescope, use averted vision to help the core of the galaxy snap into definition, and look carefully for the delicate lacework of dark dust lanes and brighter patches of stars.

NGC 55 has a modest surface brightness, but its core takes magnification well.  Try 60x to 80x to bring out more detail.  And look especially for the dark rift that cuts from the core and out through the eastern section of the galaxy. Truly stunning.

ngc-55-ngc-300-map

Location of galaxies NGC 55 and NGC 300 in the southern constellation Sculptor. North is up and east is to the left.

NGC 55 is about 7 million light years away, which makes it one of the nearest of all galaxies. At magnitude 8.1, it’s one of the dozen brightest galaxies in the heavens, and perhaps one of the four or five most detailed galaxies for observers with a small telescope, especially for observers in the southern hemisphere.

NGC 300 lies at about the same distance as NGC 55 and shines with the same brightness. But its light is spread over a larger apparent surface, so it looks fainter and is harder to find in a small telescope.  Look for it about 1.8o northwest of the star xi (ξ) Sculptoris.

A rough sketch of NGC 55 made with a 10" f/4.7 Newtonian reflector at 65x.

A rough sketch of NGC 55 made with a 10″ f/4.7 Newtonian reflector at 65x.

While not as striking as NGC 55, NGC 300 is still a compelling sight in a 4-inch or larger scope at low power.  There are traces of two spiral arms visible in very dark sky.  The overall view brightens in an 8-inch or larger scope, but lower power usually gives a better view.  The galaxy grows apparently larger but dims appreciably at higher magnification.  Look also for a number of foreground stars superimposed on the galaxy.  These stars often tantalize supernova hunters who mistake them for exploding stars.

Astronomers have long considered NGC 55 and NGC 300 to be members of the Sculptor Group. But they are sufficiently far away from NGC 253 and other Sculptor galaxies that some doubt they are truly members. They may be only foreground objects.

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