CHRONOMETER

Today, a chronometer is a mechanical watch whose accuracy has been verified and certified according to the international standard ISO 3159. Various bodies are authorised and accredited to issue these certifications. Currently, the Official Swiss Chronometer Testing Institute (COSC) and Timelab are the Swiss institutions certifying according to ISO 3159.

In the past, chronometry certificates were issued by astronomical observatories based on national standards or criteria specific to each observatory.

Useful links:

– Certification of chronometers according to the ISO 3159 standard