UDF 423 is thespiral galaxy in the lower right quadrant of the Hubble Ultra Deep Field.
UDF 423 is the Hubble Ultra Deep Field (UDF) identifier for a distant spiral galaxy. With anapparent magnitude of 20,[1] UDF 423 is one of the brightest galaxies in the HUDF and also has one of the largestapparent sizes in the HUDF.[1]
The "distance" of a far away galaxy depends onhow it is measured. With aredshift of 1,[2] light from this galaxy is estimated to have taken around 7.7billion years to reach Earth.[3] However, since this galaxy is receding from Earth, the presentcomoving distance is estimated to be around 10 billionlight-years away.[3] In context, Hubble is observing this galaxy as it appeared when the Universe was around 4.9 billion years old.[3]
