What is the covalent compound formula for Nitric Acid?

It would be $N {O}_{2} O H$
Imagine the $N$ with 5 valencies, in the centre. Four of those are taken by two double-bonded $O$, and the fifth is taken by an $O H$
In a watery environment, the $H$ is quickly 'donated' to a water molecule in the form of an ${H}^{+}$ to form the hydronium or acid ion ${H}_{3} {O}^{+}$, leving the $N {O}_{3}^{-}$ ion.