sci22073 — Announcement

Observatories at Cerro Tololo and Cerro Pachon in Chile closed due to snow

July 21, 2022

Update 28 July 2022:: Science operations at Cerro Tololo and Cerro Pachón have been resumed after the big 14–15 July 2022 winter storm, The roads to both summits are open again. Power has been restored to both summits, although Pachón will remain without commercial power for another 2-3 weeks while power line repairs are carried out. This is the last update on this topic.

Update 26 July 2022: The access road to Cerro Tololo is fully open while the road to Cerro Pachón will be open from tomorrow. The snow has nearly melted at the summits. Power has been restored to Tololo. Pachón will remain without commercial power for some weeks until repairs to the power line can be carried out, but science operations can be resumed on generator power. DECam at the Víctor M. Blanco 4-meter Telescope has been started up again and appears to be in good shape. Night-time operations at Cerro Tololo, on Gemini South, and on SOAR are planned for tomorrow, Wednesday 27 July.

Update 20 July 2022: The road to Cerro Pachón was opened at the end of the day yesterday. Today teams for Gemini, SOAR and Rubin have visited Cerro Pachón to carry out initial inspections of their facilities. On Cerro Tololo work has been underway since yesterday to restore DECam at the Blanco telescope to operation. However, some days of work remain to return all these facilities and the supporting infrastructure to normal, permitting the resumption of observations.

Update 16 July 2022: Our observatories at Cerro Tololo and Cerro Pachón in Chile (CTIO incl. SOAR and Gemini South) have been closed due to an unusually strong winter storm. Staff have been evacuated. We expect to remain without access to the sites for the next few days.


Access to both Cerro Tololo and Cerro Pachón in Chile was suspended this past week due to an unusually powerful Chilean winter snow storm that struck Thursday and Friday, 14–15 July 2022. The rare storm dropped approximately 1.5 meters of snow at the summit of both mountains, making the access roads impassable for a time. The storm had also caused the loss of commercial power to both observatories by Friday morning.

Thanks to the efforts of the road crews, a single track road was cleared to the Cerro Tololo hotel on Friday afternoon, but there was no time to clear the summit roads to get access to the telescope or power house. It was also impossible to open a road to Cerro Pachón. It was decided to evacuate the 20 staff then on Tololo, leaving no one on the mountain overnight. However, a group of 5 staff was left on Cerro Pachón, safe, warm, and supplied with food at the hotel, but unable to leave. Out of an abundance of caution, this group was evacuated by helicopter on Saturday afternoon. 

At  2 a.m. on Saturday morning, the Cerro Tololo generator failed, leaving the site completely without power. Thanks to the battery backup systems on the computer systems, however, NOIRLab staff were able to carry out a successful semi-controlled warm up and shut down of DECam on the Víctor M. Blanco 4-meter Telescope from La Serena to prevent possible damage due to the loss of power. 

The road to the Pachón hotel was finally opened late on Tuesday afternoon. The weather has since improved, clear skies have returned and temperatures have risen.

Work continues to improve road access to allow refueling of the various generators and to repair the power lines to restore commercial power. NOIRLab staff are also inspecting DECam to ensure there is no damage from the abrupt warm up before cooling it down again in preparation to resume observations. It will take a few more days for things to return to normal on both mountain tops so that science can once more get under way.

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