Figure 6.
GPI NRM “snowflakes”
observed during the
commissioning time
in May 2015. Left: Raw
data frame. Right:
Power spectrum.
Non-redundant Masking
with GPI
Commissioning of the Gemini Planet Imager (GPI) Non-Redundant Mask (NRM) mode
was scheduled for late March, and coincided with the horrendous flooding event
described below. Because of this, no data
were taken. Since this mode was to produce some of the highest-contrast observations with GPI, we rescheduled a commissioning night in May. The team, led by Peter
Tuthill and Alexandra Greenbaum, visited
the telescope and obtained a night’s worth
of useful data, which they are now working
to reduce.
Future users will need to become familiar
with the “snowflake” patterns produced
when the seeing is good and the NRM mask
is in place; two samples of this effect appear
in Figure 6.
Figure 7.
Aftermath of the
major rainfall in Chile,
March 2015
14
For the technically inclined, the raw image
taken through the mask can be thought of
as an interferogram — a pattern formed
from fringes containing high spatial resolution; these cross the Airy disk diffraction
pattern caused by the individual circular
holes. The power spectrum image shows
fringe power at 45 individual baselines;
these correspond to each pair of holes in
the mask and reveal the surprising degree
of inherent order in the image.
GeminiFocus
Data Center Re-engineering
Relatively unseen by the outside user, the
summit data centers have been re-engineered over the past six months. The new
data centers are split into hot and cold
zones, producing significant energy savings. They also foster greater sustainability
and cybersecurity.
Destructive Weather Event
in Chile
Near the end of March, Chile suffered a freak
storm that dumped many inches of rain on
the high deserts and caused major flooding
and destruction right down to the coast.
Cerro Pachón was one of the affected areas.
As a result, Gemini South lost power, communications, and nights of telescope time.
Figure 7 shows some of the aftermath of
the flooding. Thanks to the quick and effective work by the engineering staff, the telescope was back on line very shortly after the
storm passed.
July 2015