This report expresses some pretty specific accuracy when determining the effect of a large galaxy's gravitational effect on the light from a distant supernova that's traveled 10 billion years across the Universe. Is this accomplished through the somewhat straightforward understanding of the lens's effect? And the distances involved, of course. And the mass of the galaxy....

But doesn't the validation of the prediction mentioned below also provide information about the cosmological parameters, basically confirming the accuracy of the standard model? Well, yes, the article later confirms that: ("Developing precise dark-matter maps of massive galaxy clusters is another way for astronomers to measure the universe's expansion rate and investigate the nature of dark energy, a mysterious form of energy that works against gravity and causes the cosmos to expand at a faster rate. ")

Hubblesite preview: Around 2037 a replay of Supernova Requiem's demise will appear in deep space.
The rebroadcast is courtesy of a giant galaxy cluster that resides in front of the faraway supernova, whose light travelled for 10 billion years across space to reach Earth. The massive cluster's powerful gravity acts like an oversized celestial zoom lens, magnifying and distorting the light from the supernova and splitting it into multiple copies. Three mirror images of Supernova Requiem were spotted by the Hubble Space Telescope scattered in an arc-like pattern across the cluster. Each image is a snapshot of the supernova's light at different times after the explosive event.