The _date variable type in PSYC is for storing absolute time values in contrast to _time which is about time deltas.
PSYC Epoch
Since 1970-01-01 is well in the past now, PSYC uses a different point in time as the zero time. That moment has been arbitrarily chosen to be Unix epoch plus 1440444041, so whenever outputting time values onto PSYC you need to subtract that constant from your unixtime value. This places PSYC epoch at 2015-08-24 21:20:41 CET allowing for a great Monday night party. The real reason for that is that it would reduce the number of bytes used by time values for a significant amount of years. By the year 2020 we probably will have reformed PSYC anyhow.
TODO: Event times like _time_log and _time_place have been stored as absolute seconds since epoch. They should be converted to _date values.
Client programmers: When either of these variables is present, you should not open up windows or tabs for these messages. We had that problem with PsycZilla for a while.. we called it "tab explosion" as one simple /log command created a plethora of chat tabs. you don't want that. it is so very unusable.