RD1 or 0140+326 RD1 is a distant galaxy, it once held the title of most distant galaxy known. RD1 was discovered in March 1998, and is at z=5.34, and was the first object found to exceed redshift

Redshift

In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...

 5. It bested the previous recordholders, a pair of galaxies at z=4.92 lensed by the galaxy cluster CL 1358+62

CL1358+62

CL 1358+62 is a galaxy cluster located at z=0.33 redshift. Behind the cluster, lensed into a red arc is an infant galaxy that was the farthest object in the observable universe for a few months. It had a record redshift of z=4.92 and was discovered on July 31, 1997 by M. Franx and G. Illingsworth....

 (CL 1358+62 G1 & CL 1358+62 G2). It was the most distant object known to mankind for a few months in 1998, until BR1202-0725 LAE was discovered at z=5.64.

Distance measurements

The "distance" of a far away galaxy depends on what distance measurement

Distance measures (cosmology)

Distance measures are used in physical cosmology to give a natural notion of the distance between two objects or events in the universe. They are often used to tie some observable quantity to another quantity that is not directly...

 you use. With a redshift

Redshift

In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...

 of 5.34, light from this galaxy is estimated to have taken around 12.5 billion years to reach us. But since this galaxy is receding from Earth, the present comoving distance

Comoving distance

In standard cosmology, comoving distance and proper distance are two closely related distance measures used by cosmologists to define distances between objects...

 is estimated to be around 26 billion light-year

Light-year

A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...

s.