Certina Certiday automatic watch

A large Certina automatic watch with a blue and white dial and day and date windows. There is a curved mark on the right side of the dial. The case shows signs of age and wear, and there is an engraving on the case back. The crown and metal bracelet are Certina branded, and the bracelet fits a wrist of approximately 19 cm. Service history is unknown, but the watch is running and has a deviation of approximately 10 seconds per day.