Hi Les,
Interesting observation.
Such a short duration.
In the literature to date, what is the shortest duration microlensing event ever observed?
Microlensing events usually occur over a period of days. For example, in this paper
of 10 years back, the shortest duration event recorded was 5 days.
http://adsabs.harvard.edu/full/1999A&A...344L..49A
Best Regards
Gary
Mt. Kuring-Gai