a news vs the news vs news

news=(uncountable)information about something that has happened recently
1)a news
2)the news
which one is incorrect?

The first one: a news is impossible in general (perhaps an unusual context could be found where it is possible, but I cannot think of any).
The other two are possible.

  • The flood was on the news today. (The television broadcast.)

A - Do come in! How is Agatha holding up? Do you bring news?
B - Yes, but the news on Agatha can wait; for I have other bad news for you first: Dorothy died yesterday at the vet’s.
A - Oh dear! That news is worse than what I expected. Please leave me alone now; I think I’ll cuddle with my remaining 732 rats for a bit.
(A message or rumour about something new that happened.)

Thank you.
I agree with you.
Now I feel certain that I was right.