Not much information easily available for this large size split second chrono
Omega named 1932 Olympic. What I have read about it: Designed by Lemania for 1932 Olympic games. It was the first 1/10 second resolution mechanical timer for Olympics with 36,000 bph balance wheel rate. Most were made for games (200+) used even after Omega photo electric timers improved resolution to 1/100 and 1/1000 seconds. A very few were made as specials for sale including several made with skeletonized movement. These were made 1970-82 with black case for dealer sale. In 2007; 300 were made in gold cases and polished parts. Omega sales started at $65K, latest at $126K. Not sure if all 300 sold. A photo copy here. Other photos are of one a watchmaker had for many years bought used cheaply on open market. 169 on dial indicates it is later than 1932 as does serial 12780620. Maybe 1952 Olympics.
70 mm diameter ss double back case, movement marked: omega letter, 202,
20 jewels, Swiss Omega watch co., not marked for adjustment. Takes 2 days to run down although 30 hour rated.