The luminosity gap between novae ( M _ { R } \leq - 10 ) and supernovae ( M _ { R } \geq - 14 ) is well known since the pioneering research of Zwicky and Hubble .
Nearby galaxy clusters and concentrations offer an excellent opportunity to search for explosions brighter than classical novae and fainter than supernovae .
Here , we present the results of a B -band survey of 23 member galaxies of the Fornax cluster , performed at the Las Campanas 2.5-m Irene duPont telescope .
Observations with a cadence of 32 minutes discovered no genuine fast transient to a limiting absolute magnitude of M _ { B } = -9.3 mag .
We provide a detailed assessment of the transient detection efficiency and the resulting upper limits on the event rate as function of peak magnitude .
Further , we discuss the discoveries of five previously unknown foreground variables which we identified as two flare stars , two W Uma type eclipsing binaries and a candidate \delta Scuti/SX Phe star .