I measured the Michelson contrast in the daytime today. It was 99.1 %. No ring heater or CO2 lasers were engaged during the measurement.

I used ASAIR_A_LF to observe the DC light at the dark port.

• bright fringe = 1156 counts
• dark fringe = 5.0 counts
• contrast = (1156 - 5) / (1156 + 5) = 0.9914