GeminiFocus July 2016 | Page 13

Contributions by Gemini staff News for Users The current semester at Gemini South has had its ups and downs: poor weather conditions have prevented almost all scheduled observations in May; but on the bright side, preventative maintenance on FLAMINGOS-2 is complete. In Hawai‘i, repairs to the Gemini North wind blind will start in early July. We’ve made several major changes to the new 2016B Observing Tool, and we invite you to contribute to the Gemini community by registering for the Gemini Data Reduction User Forum. Figure 1. Gemini South’s shutters remained closed for most of May 2016, due to persistent poor weather. Photo credit: Sandra Romero, Gemini A Month to Forget May 2016 may have been the worst month ever for weather at Gemini South on Cerro Pachón in Chile. In an average year, May is the first of five “bad” months, with weather loss usually on the order of 30% (see the chart in News for Users in the April 2016 GeminiFocus). By contrast, in May 2016, we had 16 nights during which we observed nothing at all, and a further seven during which we observed for less than three hours; in fact, weather interrupted observations every night to some degree during this period. An extended and unusually poor weather period started in April and lasted well into June, with mainly high clouds as seen in Figure 1 (but resulting in surprisingly little precipitation). This could be an effect of the strong El Niño event that is gradually ending. Given that, on average, weather losses on Cerro Pachón peak in June and July, we can only hope that 2016 isn’t “average,” and that we will have better observing conditions in the following months. Obviously, the impact on observations has been significant. Bad weather wiped out most of the Phoenix visiting instrument run and greatly hin- July 2016 GeminiFocus 11