You already know it's a Constellation. The model reference is 14381. The movement is a calibre 551 and the approximate production date can be googled from the long serial number on the movement. The crown looks to be an original decagonal, which is a plus. Without pictures of the front, it's really not possible to add any further observations. Are you looking to buy, sell, keep, or what?
My bad about the above link. Watch is stainless steel, not gold, and looks MUCH more like this 1950s version. https://shop.hodinkee.com/products/1950s-omega-constellation-reference-14381?variant=16468884612
I think it is a 1959 model - caveat, I am definitely not one of the experts on here, but I am learning and think I have it correctly aged but happy to be corrected.
Without the serial that is impossible to tell. There are curved lug 2 liners like that right up until 1961 or so. Noting the -11 iteration I would suggest it is likely one of the later not earlier 2 liners. 60-61 would be my guess. My -9 is from 1960 I believe.
I would put that serial at around 1961. It must be one of the last curved lug ie pre dog leg Connies. Others may be able to contribute their opinions based on their own similar watches. The model is written inside the caseback as per your first pictures, 14381-11.
Mine is a 17.75m serial gold cap version, iteration -9 which I date to 1960:
