The redshift of the distinct blue arc extending 35 arc-sec is measured at z=1.7, indicating that the lensed background galaxy is located about 8.8 billion light years from Earth.
The blue arc actually shows 3 copies of the background galaxy, another “counterimage” is visible at the opposite side of the cluster.
The fainter arcs, visible best in the HST image are lensed images of other more distant background galaxies. The lensing foreground cluster is measured at z=0.56 or 5.5 billion light-years distance.
The apparent overall diameter of the foreground galaxy cluster is about 0.6 arc-min arc-minutes. Its members are shining at apparent mag 21.5 to mag 24.
Find a nice very detailed 2012 publication on this lensing system here.
Find a Hubble publication with images of the lensing cluster and arcs here.
LRGB (640-180-180-200 min) total 20 h, north is up, seeing 0.8-1.1 arc-sec,
80cm f/7 Astrooptik Keller cassegrain, FLI PL-16803, Astrodon gen2 filters, Prompt 7 CTIO Chile
Processing: Johannes Schedler
Find here a 22 arc-min full frame exposure in 25/70% size, a center crop in 45/150% size and an inverted cropped image in 100/200% size with the lensed arcs marked.
To the right there is a faint arc visible that could be a result from another maybe unknown lensing system. At bottom there is an animation for comparison with the Hubble Image.