What is bottom of the hour meaning?

"Bottom of the hour" refers to the exact moment when the minute hand of a clock is pointing exactly at the 6 on the clock face marking the mid-point of an hour. For example, if it is currently 2:30 PM, the bottom of the hour would be at 2:30:00 PM exactly. The term "bottom of the hour" is often used in broadcasting, particularly in radio and television, to refer to the time 30 minutes past the hour, which is when news broadcasts and other scheduled programming often begin.