Claw Galaxy (NGC 247)

NGC 247
NGC 247: Image taken with WFI at La Silla Observatory in Chile © ESO 2011 [631]


This galaxy was discovered by William Herschel on 20th October 1784 using his 18.7 inch reflector. He cataloged it as V 20 (class V = very large nebulae) and noted: «A streak of light, nearly along the meridian, 26' long, 3 or 4' broad, pretty bright.» [463] Dreyer added it as NGC 247 to his «New General Catalogue» published in 1888. [313]

Physical Properties

NGC 247 is a dwarf, low surface brightness galaxy and of morphological type SAB(s)d. It is part of the Sculptor Group, a collection of galaxies associated with the Sculptor Galaxy (NGC 253). This is the nearest group of galaxies to the Local Group, which includes our Milky Way. A remarkable feature of this galaxy is a large void in the northern part of the disk. At a distance of about 3.5 Mpc, the void region in NGC 247 is approximately 3.4 kpc long. This is not empty space, but it contains mostly older, redder stars and no blue, younger stars. An analysis of age versus radius suggests little to no star formation in the void for more than 1 Gyr. It is speculated that it is caused by a recent interaction with a nearly dark subhalo that collided with the disc. [632]

Revised+Historic NGC/IC, Version 22/9, © Dr. Wolfgang Steinicke [277]
DesignationNGC 247
TypeGx (SBcd)
Right Ascension (J2000.0)00h 47m 08.3s
Declination (J2000.0)-20° 45' 36"
Diameter19.2 × 5.5 arcmin
Photographic (blue) magnitude9.7 mag
Visual magnitude9.1 mag
Surface brightness14.4 mag·arcmin-2
Position Angle172°
Distance derived from z2.20 Mpc
Metric Distance3.590 Mpc
Dreyer DescriptionF, eL, vm E 172°
Identification, RemarksESO 540-22, MCG -4-3-5, UGCA 11, IRAS 00446-2101

Finder Chart

The galaxy NGC 247 is located in the constellation Cetus. Just 4.5° to the south is the Silverdollar (NGC 253). The best observation time is September to December.

Finder Chart Claw Galaxy (NGC 247)
Claw Galaxy (NGC 247) in constellation Cetus. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Visual Observation

Description pending ...

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