NGC 147

NGC 147
NGC 147
	Hubble Space Telescope image of NGC 147
Observation data (J2000 epoch)
Constellation	Cassiopeia
Right ascension	00h 33m 12.1s
Declination	+48° 30′ 32″
Redshift	-193 ± 3 km/s
Distance	2.53 ± 0.11 Mly (780 ± 30 kpc)[a]
Apparent magnitude (V)	10.5
Characteristics
Type	dSph/dE5
Apparent size (V)	13.2′ × 7.8′
Notable features	satellite galaxy of M31
Other designations
	PGC 2004, UGC 326, DDO 3, LEDA 2004, Caldwell 17

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NGC 147 (also known as DDO3 or Caldwell 17) is a dwarf spheroidal galaxy about 2.58 Mly away in the constellation Cassiopeia. NGC 147 is a member of the Local group of galaxies and a satellite galaxy of the Andromeda Galaxy (M31). It forms a physical pair with the nearby galaxy NGC 185,^[5] another remote satellite of M31. It was discovered by John Herschel in September 1829. Visually it is both fainter and slightly larger than NGC 185 (and therefore has a considerably lower surface brightness). This means that NGC 147 is more difficult to see than NGC 185, which is visible in small telescopes. In the Webb Society Deep-Sky Observer's Handbook,^[6] the visual appearance of NGC 147 is described as follows:

Large, quite faint, irregularly round; it brightens in the middle to a stellar nucleus.

The membership of NGC 147 in the Local Group was confirmed by Walter Baade in 1944 when he was able to resolve the galaxy into individual stars with the 100-inch (2.5 m) telescope at Mount Wilson near Los Angeles.

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ "NASA/IPAC Extragalactic Database". Results for NGC 147. Retrieved 2006-12-07.
^ Cite error: The named reference tonryetal2001 was invoked but never defined (see the help page).
^ Cite error: The named reference McConnachie2005 was invoked but never defined (see the help page).
^ Karachentsev, I. D.; Kashibadze, O. G. (2006). "Masses of the local group and of the M81 group estimated from distortions in the local velocity field". Astrophysics. 49 (1): 3–18. Bibcode:2006Ap.....49....3K. doi:10.1007/s10511-006-0002-6. S2CID 120973010.
^ "NGC 147". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-12-07.
^ Jones, K. G. (1981). Webb Society Deep-Sky Observer's Handbook. Enslow Publishers. ISBN 978-0-89490-134-8.

[ned-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ "NASA/IPAC Extragalactic Database". Results for NGC 147. Retrieved 2006-12-07.

[tonryetal2001-2] Cite error: The named reference tonryetal2001 was invoked but never defined (see the help page).

[McConnachie2005-3] Cite error: The named reference McConnachie2005 was invoked but never defined (see the help page).

[Karachentsevetal2006-4] Karachentsev, I. D.; Kashibadze, O. G. (2006). "Masses of the local group and of the M81 group estimated from distortions in the local velocity field". Astrophysics. 49 (1): 3–18. Bibcode:2006Ap.....49....3K. doi:10.1007/s10511-006-0002-6. S2CID 120973010.

[simbad-5] "NGC 147". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-12-07.

[Webb-6] Jones, K. G. (1981). Webb Society Deep-Sky Observer's Handbook. Enslow Publishers. ISBN 978-0-89490-134-8.

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