Omega Constellation Square Case

Hello everyone, I've posted about this watch two hours ago in another forum, but I wanted more opinions on it. It is an omega constellation automatic from somewhere in the seventies, my grandfather bought it new and he gave it to me as a gift five years ago. I wanted more opinions on the case back, since it doesn't have the usual observatory on it. Anyway I'm completely sure it is authentic, it was serviced by an omega authorised jeweller and so. Sometime in the future I will open it so I can see what machine calibre it has. I will appreciate if you could help me identify my watch more accurately since I have never seen another one like it before. Thank you all

Hello

I think only the chronometer movement watches have the observatory logo. Yours must have a 1012 inside, that is a very good and accurate movement.
IMO in would need a gentle polishing. What happened to you date disc? on the brink of jumping or stuck?

hello. what is this ref. no ?