Columba

Columba was created by Dutch astronomer Petrus Plancius in 1592 in order to differentiate the 'unformed stars' of the large constellation Canis Major. Plancius first depicted Columba on the small celestial planispheres of his large wall map of 1592. It is also shown on his smaller world map of 1594 and on early Dutch celestial globes. Plancius originally named the constellation Columba Noachi ("Noah's Dove"), referring to the dove that gave Noah the information that the Great Flood was receding. This name is found on early 17th-century celestial globes and star atlases, the constellation was incorporated in 1603 by Johann Bayer in his sky atlas Uranometria.

It is a fairly small constellation at some 270º sq in size. It lies south of Lepus. It can be recognised by two mag 3.0 stars and a smattering of less brighter ones.

The constellation culminates around midnight on the 17th of December. Objects of interest in Columba include a few double stars and the lovely globular cluster NGC 1851. There are also numerous extra-galactic nebulae with two notable ones being NGC 1792 and NGC 1808 which are within 1º of each other.

NGC 1851

Discovered by: James Dunlop (1793 - 1848) Year of Discovery: 1826

"NGC 1851 = ESO 305-SC016

05 14 06.3 -40 02 50

V = 7.2; Size 11.0

13.1" (2/20/04 - Costa Rica): at 200x, this compact globular is very bright, strongly concentrated with an intense 1.5' core and a 4-5' fainter halo. The core is very lively and there are ~30 stars resolved, mostly in the loose halo. A neat loop of stars emerges from the core and runs NNE-SSW along the west edge of the core.

8": small, very small bright core, faint halo"

- by Steve Gottlieb.

NGC 1792

Discovered by James Dunlop in 1826. A description from the NGC/IC database as follows:

"NGC 1792 = ESO 305-006 = MCG -06-12-004 = LGG 127-001 = PGC 16709

05 05 14.0 -37 58 47

V = 10.2; Size 5.2x2.6; SB = 12.9; PA = 137d

13.1" (2/20/04 - Costa Rica): at 105x appears as a bright, large oval ~2:1 NW-SE, 3.2'x1.6'. Broad concentration to a large bright core and then sharply concentrated with a bright, 15" nucleus. The surface brightness is irregular with a mottled texture. A faint star is just preceding the WNW tip. At 166x, the galaxy appears brighter along the major axis with some areas of lower surface brightness giving a hint of spiral structure! A mag 14 star is preceding. Brightest in a group with N1808 40' NE.

8": moderately bright, moderately large, slightly elongated."

-by Steve Gottlieb

NGC 1808

Discovered by: James Dunlop, Year of Discovery: 1826

NGC 1808 is a barred spiral galaxy located about 40 million light-years away. Morgan (1958) first noted a group of optical hotspots in the central 1kpc region of NGC 1808. Sersic & Pastoriza (1965) included NGC 1808 in their catalogue of galaxies with peculiar and complex nuclei. Larson & Tinsley, 1978, and van den Berg, 1978, noted that NGC 1808's peculiar optical morphology is similar to M82, and starburst activity may have been induced by tidal interaction with nearby NGC 1792, which also appears to have an asymmetric morphology.

Ground-based images show that the outer spiral arms of the galaxy are warped with respect to the inner arms (which display a prominent dark dust lane). This is evidence that NGC 1808 may have had a tidal interaction with another nearby galaxy, NGC 1792. Such an interaction could have created the bar morphology, and hurled gas towards the nucleus of NGC 1808, igniting the exceptional burst of star formation seen there.

Description from the NGC/IC database as follows:

"NGC 1808 = ESO 305-008 = MCG -06-12-005 = LGG 127-002 = PGC 16779

05 07 42.3 -37 30 47

V = 9.9; Size 6.5x3.9; SB = 13.3; PA = 133d

13.1" (2/20/04 - Costa Rica): this 105x this striking starburst galaxy appeared bright, large, very elongated 4:1 NW-SE, 5'x1.3'. Sharply concentrated with a well-defined 20" core which brightens to a stellar nucleus. There appears to be an irregular extension at the NW end which brightens and is offset to the major axis [on photos this corresponds to a start of a spiral arm which is attached at the N edge of the NW end of the galaxy]. At 166x, the halo is irregular and mottled. Brightest in a group with N1792 40' SW.

17.5": bright, fairly large, small elongated core, long thin arms 4:1 NW-SE. A mag 14 star is off the NW end. This is a very pleasing galaxy.

8": fairly bright, elongated NW-SE, moderately large, bright core."

-by Steve Gottlieb

α COLUMBAE

R.A.05 39.6 DEC-34 04 MAG1=2.8 MAG2=12.5 SEP=13.5 PA=359 SPEC=B8

γ COLUMBAE

R.A.05 57.5 DEC-35 17 MAG1=4.4 MAG2=12.7 SEP=33.8 PA=110 SPEC= B3

CLEAR SKIES

References:

http://www.dibonsmith.com/constel.htm

Astronomy 2009

NGC/IC Database

CDS Strasburg

http://www.maa.clell.de/Messier/E/m074.html.