I have to chose between present simple and present continuous :

I am studying/study tonight.

I know that the right choice would be the present continuous but is it possible to use the present simple with tonight?What's the difference?
The present simple there sounds like a schedule: The train leaves tonight at 8 PM
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"I study tonight" is incorrect. Either it is "I will study tonight" or "I study at nights".
It is not incorrect, rajesh; it just has very limited use.