How to schedule a script in crontab.

Hi,

My script is in $home/bin/sample.sh.
I want to run the script for 3times a day,
first execution will be at 08:00 am.
second execution will be at 16:00 pm
third will be at 23:59 pm.

what will be the entry with this requirement??

put in cronjob

0 0,8,16 * * * $home/bin/sample.sh

and why need the script to run at 23:59, not midnight?