Veil nebula(NGC6960)

Optics: Quattro200P with coma corrector

Camera: ASI2600MC Pro

Mount: EQ6-R

Exposure: Light-120sec 30frames, Bias, Flat, Dark

Date: 2/8/2024, @Yamagata Japan

 

Something unexpected appeared around the lower left of the center. I wonder what this red arc-shaped object is.

 

Done