We report observations of three gravitationally lensed supernovae ( SNe ) in the Cluster Lensing And Supernova survey with Hubble ( CLASH ) Multi-Cycle Treasury program .
These objects , SN CLO12Car ( z = 1.28 ) , SN CLN12Did ( z = 0.85 ) , and SN CLA11Tib ( z = 1.14 ) , are located behind three different clusters , MACSJ1720.2+3536 ( z = 0.391 ) , RXJ1532.9+3021 ( z = 0.345 ) , and Abell 383 ( z = 0.187 ) , respectively .
Each SN was detected in Hubble Space Telescope ( HST ) optical and infrared images .
Based on photometric classification , we find that SNe CLO12Car and CLN12Did are likely to be Type Ia supernovae ( SNe Ia ) , while the classification of SN CLA11Tib is inconclusive .
Using multi-color light-curve fits to determine a standardized SN Ia luminosity distance , we infer that SN CLO12Car was \sim 1.0 \pm 0.2 mag brighter than field SNe Ia at a similar redshift and ascribe this to gravitational lens magnification .
Similarly , SN CLN12Did is \sim 0.2 \pm 0.2 mag brighter than field SNe Ia .
We derive independent estimates of the predicted magnification from CLASH strong+weak lensing maps of the clusters ( in magnitude units , 2.5 \log _ { 10 } \mu ) : 0.83 \pm 0.16 mag for SN CLO12Car , 0.28 \pm 0.08 mag for SN CLN12Did , and 0.43 \pm 0.11 mag for SN CLA11Tib .
The two SNe Ia provide a new test of the cluster lens model predictions : we find that the magnifications based on the SN Ia brightness and those predicted by the lens maps are consistent .
Our results herald the promise of future observations of samples of cluster-lensed SNe Ia ( from the ground or space ) to help illuminate the dark-matter distribution in clusters of galaxies , through the direct determination of absolute magnifications .