2017B Retrospective
Now that we’re in 2018A, the time has come
for a brief recap of events in 2017B at the
two Gemini sites. Mixed fortunes with the
weather, plenty of visiting observing, and
some exciting astronomical events charac-
terized the semester.
Hawai‘i
At Gemini North, the semester started later
than usual while we finished repairing the
shutter in late August. That, combined with
weather loss later in the semester, meant
that we had less science time on-sky than
usual. This adversely hit completion rates in
Band 1, but Band 2 programs held up reason-
ably well compared to previous B semesters.
When we were on the sky, conditions were
reasonably good and so Band 3 completion
rates ended up relatively low.
Visiting observers came through Gemini
North fairly regularly, conducting four short
classical runs and three more extended Pri-
ority Visitor runs.
Figure 1.
The number of nights
on which Gemini South
responded to a Standard
ToO request (left) and a
Rapid ToO request (right).
18
Following up on the interstellar asteroid
‘Oumuamua (see the January 2018 issue of
GeminiFocus, page 4) kept us busy and ex-
cited. ‘Oumuamua was discovered during
an ‘Alopeke commissioning run, and we’re
grateful to the ‘Alopeke team for bearing with
us while we overrode their time to catch this
extraordinary and unprecedented event; this
sacrifice enabled Gemini to help characterize
GeminiFocus
the peculiar properties of this exotic visitor.
‘Alopeke commissioning was, incidentally,
completed, despite this interruption.
Chile
Early 2017B brought with it the LIGO gravi-
tational wave event whose source Gemini
South brought into focus, capturing early
optical and infrared light from this merger
of two neutron stars (see the October 2017
issue of GeminiFocus, page 7). This exciting
first-time event kept staff busy for a couple
of weeks and required delaying some reme-
dial work on FLAMINGOS-2; this was scien-
tifically well worth it, as we used the instru-
ment to produce some compelling infrared
spectroscopy that confirmed the nature of
the event’s afterglow. See more on FLAMIN-
GOS-2, below.
While the first part of the semester present-
ed some weather issues, the second brought
much better weather, so we were able to
catch up on the Band-1 programs and bring
the completion rate back to reasonable lev-
els. Late in the semester we received a re-
markable number of Target of Opportunity
(ToO) triggers: in January alone, there were
31 triggers, peaking at four on a single day.
Figure 1 shows the number of nights on
which Gemini South responded to a ToO re-
quest per month (left: Standard ToOs; right:
Rapid ToOs). Most of the variation, and in
particular the end of the semester bump,
April 2018