Less than 1% of Core-Collapse Supernovae in the local universe occur in
  elliptical galaxies
  We present observations of three Core-collapse supernovae (CCSNe) in
elliptical hosts, detected by the Zwicky Transient Facility Bright Transient
Survey (BTS). SN 2019ape is a SN Ic that exploded in the main body of a typical
elliptical galaxy. Its properties are consistent with an explosion of a regular
SN Ic progenitor. A secondary g-band light curve peak could indicate
interaction of the ejecta with circumstellar material (CSM). An
H$\alpha$-emitting source at the explosion site suggests a residual local star
formation origin. SN 2018fsh and SN 2020uik are SNe II which exploded in the
outskirts of elliptical galaxies. SN 2020uik shows typical spectra for SNe II,
while SN 2018fsh shows a boxy nebular H$\alpha$ profile, a signature of CSM
interaction. We combine these 3 SNe with 7 events from the literature and
analyze their hosts as a sample. We present multi-wavelength photometry of the
hosts, and compare this to archival photometry of all BTS hosts. Using the
spectroscopically complete BTS we conclude that $0.3\%^{+0.3}_{-0.1}$ of all
CCSNe occur in elliptical galaxies. We derive star-formation rates and stellar
masses for the host-galaxies and compare them to the properties of other SN
hosts. We show that CCSNe in ellipticals have larger physical separations from
their hosts compared to SNe Ia in elliptical galaxies, and discuss implications
for star-forming activity in elliptical galaxies.
