I am doing a research paper and was hoping someone could answer this question for me. All 4 famous photos of the incident occurred around noon. i was hoping for the exact time.
Hopefully, this answer is OK – if not I am more than happy to remove.
About a year ago, an AP staff photographer answered AMAs about this very incident – the thread and answer in question is here.
I'm not sure that he ever mentions the exact time, though. He does hint at it (his mentions of being shot at, and when he started running, for example) but its not definitively answered.