  The detection of obscured supernovae (SNe) in near-infrared monitoring
campaigns of starburst galaxies has shown that a significant fraction of SNe is
missed by optical surveys. However, the number of SNe detected in ground-based
near-IR observations is still significantly lower than the number of SNe
extrapolated from the FIR luminosity of the hosts. A possibility is that most
SNe occur within the nuclear regions, where the limited angular resolution of
ground-based observations prevents their detection. This issue prompted us to
exploit the superior angular resolution of NICMOS-HST to search for obscured
SNe within the first kpc from the nucleus of strong starbursting galaxies. A
total of 17 galaxies were observed in SNAPSHOT mode. Based on their FIR
luminosity, we expected to detect not less than ~12 SNe. However, no confirmed
SN event was found. From our data we derive an observed nuclear SN rate <0.5
SN/yr per galaxy. The shortage of SN detections can be explained by a
combination of several effects. The most important are: i) the existence of a
strong extinction, A_V>11; ii) most SNe occur within the first 0.5" (which
corresponds in our sample to about 500pc) where even NICMOS is unable to detect
SN events.
