The heliacal rising of the star Sirius (The Dog star) occurs the day when the star first becomes visible above the eastern horizon at dawn, just before the sunrise. The previous days, the star is not visible because of being too close to the Sun (in the celestial sphere). This occurs when the Sirius is at least at an altitude of 3 degrees while the Sun is 8 degrees below the horizon.
The date for this occurrence in Mid Michigan in 2023(43 degrees north latitude) is August 18.
The 40 days that follow are known as the Dog Days of the Summer
The Sun is 8 degrees below the horizon and Sirius is 3 degreees above it.
