the post on 04/20/2020 to LIGO Scientific Collaboration:
You can also check out this cool infographic about #GW190412, which captures the main new features of this latest detection: the clearly unequal masses of its two black holes and the higher harmonics in its waveform- measured clearly for the first time.
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Interesting claim of higher harmonics!
LIGO is so sensitive any disturbance being detected by the interferometers is magnified many times so a tiny ripple in the rigid crust could become ringing, even measured as harmonics.
LIGO reported 5 GW events for 4 lunar events in April 2019.
S190408an - after New moon on 190405
S190412m - prior to Perigee on 190416
S190421ar - after Full Moon on 190419
S190425z - after Moon+Jupiter on 190423
S190426c - after Moon+Jupiter on 190423
On April 12, 2019, for GW190412, the Moon was getting closer to Earth while the Sun was moving away from its lunar alignment. LIGO triggered on these changes in the crust caused by these external tidal forces, which are not astrophysical in nature.
On April 23, 2019 Moon and Jupiter were in near alignment. It is a true testament to LIGO's extreme sensitivity when LIGO reported 2 GW detections after the peak of this celestial alignment. One can wonder about the strength of the GW ringing which persisted for 3 days.
The 'chirp' makes for funny interviews but it originates in the LIGO extreme sensitivity not in the gravitational wave.