What Is An Observatory? Cosc Observatory Table Decryption

If you have experience in watch purchase, then the term COSC Observatory will not be unfamiliar, this word will appear repeatedly in the mouth of the salesperson, and many people may not really understand COSC until the end of the purchase What exactly does the Observatory certification mean, or what it means. The editor of the Watch House will introduce the certification of the COSC Observatory in a comprehensive way, and take a look at what the COSC Observatory watch is.

COSC Observatory
   COSC is the abbreviation of Controle Officiel Suisse des Chronometres. It means that the movement of the watch is sent to the Swiss Observatory for accuracy test. Any movement that can pass the accuracy test can be marked with Chronometer on the dial.

   ‘Chronometer’ is generally interpreted as ‘precision timer’ in English dictionaries. It is derived from the combination of Greek Chronos and Metron in terms of etymology.
   The Swiss Official Observatory Testing Agency is an independent official agency, referred to as COSC. Founded in 1973 by five Swiss watchmaking states (Bern, Geneva, Neuchâtel, Solothurn and Vaud) and the Swiss Watch Industry Federation, it is now a non-profit legal organization.

cosc test-16-day test cycle, seven tests
  A test cycle is 16 days. All tested watches are assigned a universal dial for testing, and the movement will be engraved with a unique identification code, and COSC will strictly implement its specified standards. This universal dial includes a reference point system that allows the image to be absolutely focused, and the measurement is not affected by changes in the position of the movement when the movement is placed under the camera.

Each watch comes to COSC with all the technical indicators of the brand (for example, the main splint of the movement is tested together). A bar code is affixed to each watch so it can be tracked throughout. The first procedure is to identify the watch on the COSC computer system, then identify the package in the tray and then automatically refining. After a rest for 24 hours, perform the first pass test.
  Over the next 15 days, a series of repeated trials will be performed, including Saturday and Sunday. In the first stage, the time displayed by the watch under test is recorded on a receiver controlled by an atomic clock. The duration of these recordings will determine the continuity of the movement experiment. Each test will be in three different time periods (6 o’clock, 3 o’clock, 9 o’clock vertical position, dial side and movement side horizontal position) and 23 ° C, 8 ° C and 38 ° C. Performed at temperature.

  COSC provides seven different tests. As long as one fails the minimum standard, it means that the movement failed the test. The seven tests are briefly described as follows:
1. Average daily difference:
  Passing the fifteen-day test, the average daily difference of the movement must be in the range of -4 seconds to +6 seconds. The average daily difference of the COSC is obtained by subtracting the time indicated by the movement on the day and observing it 24 hours ago. The movement indicates the time to get.
2. Average daily variation:
 COSC measures the travel time error of five positions every day, two horizontal directions and three vertical directions. After fifteen days of testing, a total of 50 bit difference data is obtained. The average daily average bit change must be less than 2 seconds.
3. Maximum daily variation:
 The maximum deviation of the five measurement positions is no more than five seconds per day.
4. Difference between horizontal position and vertical position:
The average position difference of the horizontal position measured on the fourteenth and fifteenth days minus the average position difference of the vertical position measured on the first and second days must be between -6 seconds and +8 seconds.
5. Maximum daily deviation:
  The difference between the maximum and average daily differences must be less than 10 seconds per day.
6. Variation of daily difference caused by temperature:
  Place the movement in an environment of 8 degrees Celsius and 38 degrees Celsius to measure the day difference, subtract the day difference of the high temperature environment from the day difference of the low temperature environment, and then divide by 30 to get the change in the day difference caused by temperature. Must be less than 0.6 seconds / day.
7. Poor recovery:
  The average daily difference measured on the last day is subtracted from the average daily difference measured on the first two days to obtain the recovery difference, and its size must be controlled within 5 seconds.


Observatory certificate of compliance
   According to COSC’s own definition, ‘Observatory watches are high-accuracy watches that can display the second hand and include a movement that have passed the official agency’s (COSC) testing for several days at different positions and temperatures. A standard movement can only be issued with an official chronometer certificate. ‘
COSC and brand

   The brand sends the watch to COSC for testing. Once the watches have been tested under severe conditions, they can get the disc logo and an observatory certification certificate. The certificate not only contains all the test data to prove it, but there are also different observatory numbers on the watch. Most of the watch factory’s observatory certificates will stay in the original factory. Consumers will see the self-made observatory card issued by the watch factory. Once, Omega had the most chronometers, and Rolex currently has the most. Basically, the seven brands of Rolex, Omega, Breitling, Mido, Tissot, Panerai and Chopard support more than 90% of the total COSC certification each year.
   During the whole certification process, the brand will definitely invest some money, which will increase the cost, so the watches that we see on the market that are certified by the Observatory are usually more expensive than those without the Observatory certification. In general, the price of a movement that passes the test will be higher than that of an equivalent movement that fails. However, not all brands are obsessed with this COSC certification. Some top brands, such as Patek Philippe, Vacheron Constantin, Audemars Piguet, will not focus on this certification, they will follow stricter testing standards.
Summary: From the above, we can see that COSC is a certification body, similar to the ISO we often hear. All movements that meet the COSC inspection standards can get a certificate of astronomy. Therefore, the observatory table is a COSC-certified table. The watch with COSC certification is not inferior to every second. The error standard of COSC is -4 / + 6.

  At present, many Swiss watch brands will send their movements to COSC for certification, thus obtaining a certification. COSC agencies have also responded to this, and they do not want to make this certification simply a marketing content for a brand. But for now, the certification of the COSC Observatory has been promoted too much. However, it is certain that astronomical watches with COSC certification can guarantee a certain accuracy, which is the most basic guarantee for the most original functions of the watch. With the wide variety of current watch promotions, this COSC certification is one of the most tangible.

  In the end, you still have to remind watch purchasers that COSC certification is only a reference basis. Don’t let it become the ultimate weapon that will control your watch purchase. As long as the current ETA movement is simply polished, it is not difficult to pass COSC certification, and a watch without COSC certification does not mean that it is not good. COSC certification is generally only for mechanical watches, because this certification is meaningless with regard to quartz watches, and their travel time accuracy will be higher than the COSC certification standard (quartz COSC certification is -0.07 / + 0.07). So don’t be fooled by COSC Observatory’s high-sounding terms. The observatory here is not related to the observatory you are familiar with. (House of Watches / Text Source)