but the time shown is 16.09 pm 39 mts after closing
What this means is that if you buy mistake instead of buying Nifty october future bought December future, you can ask your broker to request for cancellation of trade.
This request will go through only if the broker/client on the other side of the trade oblige. 99.99% of the times it never happens.
But in such cases, if there is any such case of modification/cancellation/annulment of trade request made, the time will show post 3.30pm..