Nagios alert time stamp - GUI and nagios.log

[hbackus]

I have Nagios Core 4.2.2 running.

The alerts in the GUI/web interface shows a time and date stamp for alerts similar to these examples:
Service Ok [01-27-2017 12:15:16] SERVICE ALERT: fw-ind-hsb;PING;OK;SOFT;2;PING OK - Packet loss = 0%, RTA = 23.38 ms
Service Warning [01-27-2017 12:14:18] SERVICE ALERT: fw-ind-hsb;PING;WARNING;SOFT;1;PING WARNING - Packet loss = 28%, RTA = 126.56 ms

The nagios.log (/usr/local/nagios/var/nagios.log) has an entry that looks similar to these examples but has a 10-digit number instead of a time & date.
[1485540916] SERVICE ALERT: fw-ind-hsb;PING;OK;SOFT;2;PING OK - Packet loss = 0%, RTA = 23.38 ms
[1485540858] SERVICE ALERT: fw-ind-hsb;PING;WARNING;SOFT;1;PING WARNING - Packet loss = 28%, RTA = 126.56 ms

The two samples are the same report on packet loss and RTA except for the nagios.log has the 10-digit number instead of a time & date.

Is there an explanation somewhere on what the 10-digit number stands for or how to Interpret its meaning or conversion to a date & time?

Thanks

[hbackus]

Never mind, I should of thought of epoch time before posting.