How long do Hanukkah candles have to burn?

I’ve always heard “30 minutes,” but I’ve never seen a source.

And should we be counting halachic minutes? Because 30 halachic minutes is about 37 minutes this time of year.

(Halacha divides day and night into 12 hours each, so in the northern hemisphere, in Winter, hours and minutes are longer than 60 civil minutes.)