Twice an hour
0,30 * * * *
At 0 and 30 minutes past the hour. Same cadence as every 30 minutes, written as an explicit list.
Check the next five runs
Output
The result shows up here. Your input is not written to the log.
Questions
›What does 0,30 * * * * mean?
At 0 and 30 minutes past the hour
›Which timezone are the next runs in?
The expression is evaluated in UTC. This page also shows those times in the timezone of the browser you are using.