I recently noticed that on my calendar, under every day, something else is written, the meaning of which I ignored. I learned that it is the Rokuyo (六曜) that are marked: a series of six days which differ in their luckiness. These days are calculated based on the lunisolar calendar. Some are lucky before noon, but bring bad luck after (先勝, sensho), or the other way round (先負, senbu). Butsumetsu (仏滅) is simply unlucky all day, since it symbolizes the day Buddha died. In fact, yesterday (butsumetsu), the hard disk of my office computer broke, I’d call this corroborating evidence!
Dates for weddings and funerals, but also shop-openings and the like are often chosen in accordance with the rokuyo.
For today, there’s no need to worry by the way: it’s Taian (大安), the most lucky of the six days.