Figure 15.
The May 4, 2018, Big
Island earthquake,
associated with intense
volcanic activity at
Kilauea volcano,
as recorded by the
secondary-mirror sensors
on Gemini North.
Figure 16.
Daily average numbers
of sub-micron-sized
particles at the Nasmyth
platform of Gemini
North.
nonetheless has been a concern, as some of
the earthquakes have been major (e.g., the
6.9-magnitude quake on May 4th, the larg-
est since 1975), and volcanic ash reaching
the summit could pose a threat to our opti-
cal systems (chiefly the primary mirror).
So far, Gemini has survived this period quite
well; the large earthquake referred to above
was felt strongly at the summit (and seen
by the secondary-mirror sensors, Figure 15),
but produced no damage to the telescope
or enclosure. As for ash, we have a particle
sensor (installed as part of the Base Facil-
January 2019 / 2018 Year in Review
ity Operations project), which gives us in-
formation on the flux of particles of various
sizes at the telescope’s elevation (Figure 16).
To date, the only major ash event which pro-
duced a significant spike happened while
the telescope was closed due to high hu-
midity; but we’re definitely living in strange
times when we have to watch for this sort of
event at night. To complete our monitoring
equipment, we are in the process of procur-
ing a sulphur dioxide (SO 2 ) detector; there
have been times when observatory staff on
the summit have reported the distinct smell
of sulphur in the air.
GeminiFocus
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