I annotate here some observations from an inspection of the Hrec spectrogram of the last 10 days:

• several peaks and broad noise reduced in correspondence to the IITF set point adjustment on the morning of July 24 ... but then growed up again (Figure 1)
  • Figure 2: reduction around 420Hz, but broader structures up to 550Hz reduce as well
  • Figure 3: reduction around 340Hz
  • Figure 4: reduction at 197Hz
• 163-167Hz peaks ALSO reduced with the tuning of the ITF set point, but seem to change in amplitude with a different pattern from those above. Some coherence with SDB1_LC for the 167Hz one. Figure 5.
• 387-385Hz peaks ALSO reduced at that time, and disappeared since July 25. They are coherent with DT_ACC: Figure 6.
• 292Hz peak was very loud before July 24th, no more present since then.... Figure 7.
• line at 497Hz has a characteristic 1 hour modulation, Figure 8