Varying time on GMT IIc.

[Gigaton Punch]

Just got a brand new GMT Iic

I have been testing the accuracy of the time on my GMT IIc compared to USNO time over the past couple days. I noticed that it's been spot on for two days, then became slower by two seconds, then caught on, then became faster by one second, and now caught on again.

Is there a reason for why the time is varying?

[Tools]

A variance of a couple of seconds a day is not unusual for a mechanical timepiece..

Watches are timed in 5 different positions and see a variance of that much just in the position the watch is oriented..

Besides, I'm not so sure that you can "eyeball" a one second a day variance..

You check a watch by setting it to your time source, then re-checking 5 or 10 days later with the same source and dividing by days. This gives you a daily variance that is extremely accurate to your wearing habits..

[77T]

Good points Larry makes...and not all internet time is created equal either. So averaging is best and anything within -4 or +6 is great.

For example, see the screenshot below comparing the USNO vs. time.is (which is Ce133 based). Even the USNO time can vary.

The precision depends on your internet connection and how busy your computer is.