J un 1 99 9 SN 1997 cy / GRB 970514 — A New Piece in the GRB Puzzle ?

We present observations of SN 1997cy, a supernova (SN) discovered as part of the Mount Stromlo Abell Cluster SN Search (Reiss et al. 1998), which does not easily fit into the traditional classification scheme for supernovae. This object's extraordinary optical properties and coincidence with GRB970514, a short duration gamma ray burst (GRB), suggest a second case, after SN 1998bw/GRB980425, for a SN–GRB association. SN 1997cy is among the most luminous SNe yet discovered (M R << −20.1, H 0 = 65), and has a peculiar spectrum. We present evidence that SN 1997cy ejected approximately 2M ⊙ of 56 Ni, supported by its late-time light curve, and FeII/[FeIII] lines in its spectrum, although it is possible that both these observations can be explained via circumstellar interaction. While SN 1998bw and SN 1997cy appear to be very different objects with respect to both their gamma ray and optical properties, SN 1997cy and the optical transient (OT) associated with GRB970508 have roughly similar late-time optical behavior. This similarity may indicate that the late-time optical output of these two intrinsically bright transient events have a common physical process. Although the connection between GRB970514 and SN 1997cy is suggestive, it is not conclusive. However, if this association is real, followup of short duration GRBs detected with BATSE or HETE2 should reveal objects similar to SN1997cy.