The NASA/IPAC EXTRAGALACTIC DATABASE (NED) lists galaxies from the European Southern Observatory (ESO) catalog as G (ESO 012- G 014) or IG (ESO 293-IG 034).

What does G/IG signify?


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These identifiers correspond to the ESO/Uppsala Survey of the ESO(B) Atlas (1982). The identifier column (ESO) is associated with the following note:

Note (1)  : ESO designation is written FFF-oooNNN, where
FFF = Field (plate) number, see file "plates.dat"
ooo = Object class with
* = star ** = double or multiple star
SC = star cluster N = nebula
A = asteroid C = comet
G = galaxy IG = interacting galaxy
EN = emission nebula PN = planetary nebula
RN = reflection nebula SNR = supernova remnant
? = questionable object
NNN = number within field

So the "G" means "galaxy" and "IG" means "interacting galaxy".


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