Supernova designators for confirmed supernovae have an IAU standard: the prefix SN followed by a year and if needed, a suffix indicating its ordinal number among the year's supernovae confirmations. (The year is the year that its EMR reached Earth.) For historical supernovae, often the year is sufficient, e.g., SN 1604. More recently many are confirmed for each year, and a suffix is added to indicate the number of its confirmation:
Example: SN 2005nc, sometimes written sn2005nc or in context, abbreviated to 2005nc.
Supernova candidates are likely to receive a survey-based designator, and if confirmed, it may continue to be known by that, e.g., if it has been studied and written about before its confirmation.