What are the unlucky days of Sagittarius?

Wednesday, because Chilon was shot by He Qiuli on Wednesday.

The kind and innocent Chilon sacrificed his life for his friend that day. Zeus knew this. He lifted Chilon's body with both hands and threw it into the sky. Chilon instantly turned into several shining stars, and his body was like a Sagittarius. Since then, this constellation has been called Sagittarius in memory of Chilon.