Gravitational Lensing of the Most Distant Known Supernova, SN1997ff

We investigate the effect of gravitational lensing on the farthest known supernova, SN1997ff. The SN was found at z~1.7 in the Hubble Deep Field North and is most likely of Type Ia. Due to our poor knowledge of the properties of the lensing foreground galaxies, we conclude that large magnification effects are possible for reasonable lens parameter values implying that this single SN does not put any strong constraints on the cosmological parameters, grey dust obscuration or luminosity evolution of SNIa until we can model the lensing with high accuracy.