K. Mogushi 
I witnessed glitches below 100Hz around 8:20UTC on Jul 20th in magnetometer x, y and z, but I do not know the cause of it.   

HAM 6 (OMC) x-axis: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170720/plots/H1-ALL_72E7D4_MEDIAN_RATIO_SPECTROGRAM-1184544018-86400.png
LEVA x-axis: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170720/plots/H1-ALL_20971E_MEDIAN_RATIO_SPECTROGRAM-1184544018-86400.png
EY x-axis: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170720/plots/H1-ALL_1D4533_MEDIAN_RATIO_SPECTROGRAM-1184544018-86400.png
HAM 6 (OMC) y-axis: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170720/plots/H1-ALL_62EF30_MEDIAN_RATIO_SPECTROGRAM-1184544018-86400.png
LEVA y-axis: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170720/plots/H1-ALL_1E6840_MEDIAN_RATIO_SPECTROGRAM-1184544018-86400.png
EX y-axis: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170720/plots/H1-ALL_AA5283_MEDIAN_RATIO_SPECTROGRAM-1184544018-86400.png
HAM 6 (OMC) z-axis: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170720/plots/H1-ALL_29F575_MEDIAN_RATIO_SPECTROGRAM-1184544018-86400.png
LEVA z-axis: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170720/plots/H1-ALL_14CF11_MEDIAN_RATIO_SPECTROGRAM-1184544018-86400.png
EX z-axis: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170720/plots/H1-ALL_60E63E_MEDIAN_RATIO_SPECTROGRAM-1184544018-86400.png