His yahrzeit (Hebrew calendar anniversary of his death) is 12 Heshvan, which this year begins the night of Sunday November 13.
I still remember gnomi and I finishing off shabbat that evening, turning on the TV in our old apartment, and hearing the news about his assassination. jik_blog and his wife were in Israel at the time, I believe; as Nomi recalls hearing from them by email about what it was like in Israel that tragic day.
(For more information, see This Day in History. Today's also the 26th anniversary of the Iranian students storming the U.S. embassy in 1979.)