Presentation #131.02 in the session Supernovae I.
We are performing an HST snapshot imaging NUV survey to determine the occurrence rate of interaction between circumstellar material (CSM) and the ejecta of supernovae (SNe) stripped of their envelopes (SNe IIb, Ib, Ic, SLSNe-I) using imaging in WFC3/F275W (z<0.15) or WFC3/F336W (z>0.15) between one to four years after explosion. Large amounts of CSM must have been ejected by the progenitors to these SNe, and the potential for significant CSM interaction, which will be bright in the UV, is present. Our HST program is targeting a sample of 163 SNe detected by the Zwicky Transient Facility. Thus far, in the current HST cycle, 34 SNe have been observed, out of which one SN is clearly detected in F336W at 550 days after explosion. Our snapshot observations are performed at an average rate of 10 observations per month. At the time of AAS 240 we expect to have observed roughly 70 SNe, which will allow us to derive and present preliminary but meaningful constraints on the occurrence rate of CSM interaction several years after explosion in these SNe. Our results will provide new constraints for both single- and binary-star models for stripped SNe.