The Free-Oscillation band during the last 30 days

Click on respective image to view it in original size.
Want to see older spectrograms? Explore subdirectories for the years
2024 |  2023 |  2022 |  2021 |  2020 |  2019 |  2018 |  2017 |  2016 |  2015 starting in June.
URL model:  http://holt.oso.chalmers.se/hgs/SCG/PNG/<year>/<month>/<day>-last-30-days.f<C>.png  
where <C> is a mark for the frequency range; in earlier years  o  or  w , in later years  m  or  n
e.g.  http://holt.oso.chalmers.se/hgs/SCG/PNG/2015/06/01-last-30-days.fo.png
For 2020, spectrograms are missing for Jan 1 to July 12.
  0 - 5 mHz
 0 - 20 mHz

The white curve shows air pressure frequency with
the frequency of the almost ever persistent oscillation
the Heater Current control loop.
this current has a noticeable
(not drawn to any scale). You might notice covariation
near 2 mHz, which we believe originates in
The OSG 054 seems to be a rare case where
effect on the gravity sensor.