| UDF 423 | |
| Epoch: | J2000 |
| Constellation Name: | Fornax |
| Ra: | [1] |
| Z: | 1 (or 0.46)[2] |
| Dist Ly: | 7.7 billion light-years (or 4.7 billion light-years) (light travel distance) ~10 billion light-years (or 5.7 billion light-years) (present comoving distance) |
| Appmag V: | 20 |
| Size V: | 0.11' x 5.04" or 0.0027' x 0.0027' |
UDF 423 is the Hubble Ultra Deep Field (UDF) identifier for a distant spiral galaxy. With an apparent magnitude of 20,[1] UDF 423 is one of the brightest galaxies in the HUDF and also has one of the largest apparent sizes in the HUDF.[1]
The "distance" of a far away galaxy depends on how it is measured. With a redshift of 1,[2] light from this galaxy is estimated to have taken around 7.7 billion years to reach Earth.[3] However, since this galaxy is receding from Earth, the present comoving distance is estimated to be around 10 billion light-years away.[3] In context, Hubble is observing this galaxy as it appeared when the Universe was around 4.9 billion years old.[3]