Tops? I'll estimate around 1kg, give or take 150g.

Story problem:

A standard clock is split into two twelve-hour portions of the day, each of which contains 60 minutes, each of which contains 60 seconds.

Imagine an advanced civilization is discovered somewhere on earth. Their day is divided into three thirteen-hour portions, each hour contains 39 minutes, and each minute contains 39 seconds.

What is the ratio of a second for this newly discovered civilisation compared to one of our seconds, and which one is larger? List your answer to 5 significant figures.