All day the storm atop our mountain continued. As we watched in the cameras the snow fell heavily, often so thick nearby structures disappeared into the white. Unlike yesterday the winds have eased, the snow quickly accumulates where it falls instead of drifting against the structures. As we watch through the day things began to vanish, railings and guardrails buried in the snow.
Observing is, of course, cancelled.
The Keck summit crew never made it up, for the second day in a row there was no one to see to the facility and the instruments. As we monitored via the remote links we knew when the last liquid nitrogen boiled away, when the instruments began to warm. Only HIRES with the attached large liquid nitrogen dewar remains cold, perhaps for a day or two more, as long as the cryogen lasts. The instruments that have warmed will need to have vacuum restored with days on a vacuum pump before they can again be cooled and returned to operation. It will be at least a week before they can again be used.
This is the heaviest snowfall we have seen in many years atop Mauna Kea. I am scheduled to go up Monday, I have things I would like to get done. Maybe, maybe not, conditions are still very much in question. Meanwhile half of the island population will be in Waimea for the annual Christmas parade, it does feel a bit like Christmas with the mountain looming white above the town.
Andrew,
Firstly, thanks for the webcam pictures of the conditions!
Secondly, a technical question. I was surprised to learn in your post that (all?) the Keck instrumentation that require cryogens use ones that require regular fills. Is there a reason that closed cycle coolers aren’t used? Just curious.
Tom
We have CCR’s on all of the new stuff, about half the instruments. NIRC2, OSIRIS, NIRSPEC, and MOSFIRE are all CCR cooled. LRIS, ESI, DEIMOS, and HIRES are nitrogen cooled.