The world is in a battle over the leap second. The leap second is a little extra second added to Coordinated Universal Time (UTC) as needed to keep clocks in sync with the Earth’s rotation. Every few years, there is a proposal before the International Telecommunications Union Radiocommunication Sector (ITU-R) to abolish the leap second and replace it with something that would have computers drift away from the rotation of the Earth.
The last time this was on the table, in 2012, it was taken off because it wasn’t ready. It’s back again this November, and we have five steps to save it:
1. Demand that your government participate in ITU-R meetings on this issue
2. Tell your government to oppose abolishing or replacing the leap second
3. Tell your government to support keeping UTC as a continuous timescale
4. Tell your government to support updating definitions of UTC and SI seconds
5. If you work for a company or organization in favor of abolishing or replacing the leap second, tell them to change their position
I have really enjoyed writing this blog. It has been a pleasure to get to know so many of you and your opinions on this issue, and I am happy to see that our voices did not go unheard.
But there is still work to be done. Even though the decision was postponed, we can not rest on our laurels: the ITU is still open to dropping the leap second in November, or even sooner if all goes well at the upcoming meetings of Working Party 7B (WP7B). So we need to finish what we started and convince them that it would be a mistake.
Here are five steps you can take:
If you want to use the leap second in your software and hardware, you can implement the following five steps to avoid being affected by the next leap second.
1. Read that leap second information is always transmitted in the last minute of a day, so it’s easy to find out the exact time when it will be inserted.
2. If you are using UTC or TAI as your time scale, then do nothing at all except wait until after the leap second is inserted.
3. If you are producing a time scale based on UTC or TAI, then also wait until after the leap second is inserted.
4. If you are producing a time scale based on GPS, GLONASS or BeiDou, then add an extra second of correction at the end of your day, just in case the satellite system is still using UTC (or TAI). This correction will be ignored if there is no leap second that day, but it will be necessary if there is a leap second.
5. If you are producing any other time scale based on atomic clocks, then correct your clocks to align with UTC (or TAI) before midnight on December 31 and apply step 4 above just in case.
leap = False
The program below asks for a year and checks whether it is a leap year or not.
A year is a leap year if it is divisible by 4, except that years divisible by 100 are not leap years unless they are also divisible by 400. For example, 1900 was not a leap year but 2000 was.*