The supernova has been nicknamed Refsdal in honour of the Norwegian astronomer Sjur Refsdal, who, in 1964, first proposed using time-delayed images from a lensed supernova to study the expansion of the Universe.
 The W. M. Keck Observatory on Mauna Kea, in Hawaii, was used to measure the redshift of the supernova’s host galaxy (z = 1.491), which is a proxy to its distance.
 Hubble observed MACS J1149.5+2223 as part of the Grism Lens Amplified Survey from Space (GLASS) and the Frontier Fields programme. Both surveys are exploiting the lensing properties of galaxy clusters to examine the dark matter within them and some of the most distant galaxies beyond them.
 Gravitational lensing magnifies the light from fainter, background objects, allowing Hubble to spy galaxies it would otherwise not be able to detect. The process was first predicted by Albert Einstein and is now being exploited by the Frontier Fields programme in order to find some of the most distant galaxies in the Universe.
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.
Image Credits: NASA, ESA
- First observation of Refsdal supernova
- Announcement on the search programme
- Link to science paper (prediction)
- Link to science paper (reappearance)
- ESO announcement
- Images of Hubble
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