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Hidden Galaxy

C5, IC 342

Proper NameHidden Galaxy
Caldwell NumberC5
NGC/IC NumberIC 342
ConstellationCamelopardalis
Right Ascension3h 46m 49s
Declination+68° 5' 46"
Distancec.11,200,000 light years
c.3,400,000 parsecs
MagnitudeApparent: +8.57
Absolute: -19.11
Mean DiameterApparent: 19.8'
Actual: 64,400 light years
Hubble TypeSABc intermediate spiral
Optimum VisibilityNovember / December (Usually visible from northern latitudes)

The Hidden Galaxy lies in the northern constellation of Camelopardalis the Giraffe, just a few degrees away from the main band of the Milky Way as it passes through Cassiopeia and Perseus to the south. To an observer on Earth, this means that the galaxy is viewed through a shroud of dust along the galactic plane of the Milky Way Galaxy. The result is extinction, a lessening of the galaxy's apparent brightness by intervening material.

Imagery provided by Aladin sky atlas

If this galaxy lay further removed from the Milky Way's band, its visual magnitude would be in the region of +6.5, placing it among the brighter galaxies in the sky. Because it is somewhat hidden behind the dust of Milky Way's cloudy disc, however, it only achieves a faint magnitude of +8.57 as seen from Earth. This clouding effect is the reason behind the name 'Hidden Galaxy'.

The Hidden Galaxy is oriented so that it appears almost perfectly face-on from our own Galaxy, making its intricate spiral structure easily discernable. The galaxy has two major spiral arms emerging from its bright central core, each curving around the other as they extend outwards, and each breaking into multiple lesser arms and spurs. Within these arms are numerous starburst regions, areas of intense stellar formation.

The Hidden Galaxy is one of two large galaxies that together form a small galactic group, the IC 342/Maffei Group, that lies some ten million light years from the Milky Way, and is thus a near neighbour of the Local Group. The other significant member of the group is the lenticular galaxy Maffei 1 in Cassiopeia, and these two major galaxies within the group are accompanied by a swarm of smaller dwarf galaxies.

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