I analyzed the lightning glitch noise as PEM injection tests and evaluated the magnetic coupling/projection. 

The projected magnetic noise for the normal time was order 1-2 below.

I plotted the lightning position for O4a.

filled face: found in the strain signal
unfilled face: not found in the strain signal
 

I compared the ambient magnetic noise in the O4b (evaluated the Hamamatsu lightning as a PEM injection) to the target sensitivity of the O4b (10Mpc) and the O5a (37Mpc) shown in JGW-G2415922 by Komori-san.

This result shows that ambient magnetic noise can be a serious noise in the O5a.
Note that this evaluation used a transient noise and was not so precise. So we need to investigate more via magnetic injection tests.

The magnetic noise projection in klog30709 was just performed for the very short-term data and the frequency resolution was bad.
So I updated this analysis:

1. Approximate the coupling function by a smooth power-low function (Fig.1)
2. Refer to the stable data of 30 minutes in the O4a (2023-05-28 10:00 here)
3. Make the magnetic field ASD (4s FFT, quadratic sum of 3-axis) and approximate the sensor noise level (Fig.3)
4. Project the magnetic field on the strain (Fig.3), for the points larger than the noise x2.