* Supernovae are often given catalog numbers: Astronomers typically use designations like SN 1987A (for the supernova discovered in 1987) or Cassiopeia A (for the supernova remnant in the constellation Cassiopeia). These are based on their discovery year and location, not a specific name.
* Historical supernovae may have been named by different cultures: Ancient civilizations like the Chinese and Koreans have records of supernovae observed centuries ago. These may have been given names related to their location in the sky or their appearance.
* Modern supernovae are often named after the astronomers who discover them: Sometimes, a newly discovered supernova will be nicknamed by the astronomers who found it.
In summary: There isn't a single, universally recognized "namer" of supernovae. The naming convention depends on the context, and the specific historical or astronomical details surrounding the supernova in question.
