 The light travel distance of the light that we observe from UDFy-38135539 (HUF.YD3) is more than 4 billion parsecs (13.1 billion light years), and it has a luminosity distance of 86.9 billion parsecs (about 283 billion light years).There are a number of different distance measures in cosmology, and both "light travel distance" and "luminosity distance" are different from the comoving distance or "proper distance" generally used in defining the size of the observable universe (comoving distance and proper distance are defined to be equal at the present cosmological time, so they can be used interchangeably when talking about the distance to an object at present, but proper distance increases with time due to the expansion of the universe, and is the distance used in Hubble's law; "see" Uses of the proper distance for more on the physical meaning of this notion of 'distance').The luminosity distance "DL" is related to a factor called the "comoving transverse distance" "DM" by the equation , where "z" is the redshift, and the comoving transverse distance is itself equal to the radial comoving distance (i.e., comoving distance between an object and ourselves) in a spatially flat universe.