Omega constellation vintage real or fake?

I've recently purchased this vintage Omega watch from eBay Germany. Is it a fake or a real one? This are pics of the seller.

Thanks for your help guys!

Better pics get better answers.

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Have you tried Google image search? Are there any other Constellations that look identical, or is that "unique"?

Oh, and how much did you pay?

I've seen many that look the same the only doubt I have are in the letters "nst" the seller didn't write much about it just that she got it as an inheritance from her grandma... she isn't sure it is original, that's why she was asking for just 180€ and I made an offer of 150€ and she accepted. I didn't find it weird because many private sellers here in Germany sell their luxury items for very low when there are no papers and the authenticity is unclear. Since she offered payment through PayPal, I took the risk.

Kind regards.