Description
A bright, z = 1.95 supernova (SN) was discovered in JWST/NIRCam imaging acquired on 2023 November 17. The SN is quintuply imaged as a result of strong gravitational lensing by a foreground galaxy cluster, detected in three locations, and remarkably is the second lensed SN found in the same host galaxy. The previous lensed SN was called “Requiem,” and therefore the new SN is named “Encore.” This makes the MACS J0138.0-2155 cluster the first known system to produce more than one multiply imaged SN. Moreover, both SN Requiem and SN Encore are Type Ia SNe (SNe Ia), making this the most distant case of a galaxy hosting two SNe Ia. We present the discovery and analysis of the SN Encore light curve, as well as the time-delay measurement of the two brightest images. Combined with a diverse set of cluster-scale lens models for this system, our time-delay measurement results in only the third lensed SN measurement of the Hubble Constant, H0, presented here. Both SN Requiem and SN Encore have a fourth image that is expected to appear within a few years of ∼2030, providing an unprecedented baseline for time-delay cosmography.