On the morning of 1 April, just prior to the long Easter weekend, a rare electrical storm struck La Serena and then made its way inland to Tololo. A tree immediately outside the La Serena scientific and technical office buildings was struck by lightning. The resulting damage was considerable, with the Ethernet, many computers, and the phone plant being put out of commission. Sterling work by local staff restored most of the computer system within 48 hours, with some workstation shuffling to provide high priority services first. The phone plant was out of service for several days waiting for spare parts to be delivered from Santiago.
Damage on Tololo was also considerable, affecting both science operations and communications between La Serena and the outside world. Despite a thoroughgoing round of disconnecting and unplugging in advance of the storm, ground strikes on the summit caused damage to telescopes and instruments, particularly the 4-m telescope control system and ancillary computers. This took some five days to completely repair. Mountain staff worked very long hours under trying circumstances dealing with multiple, sometimes subtly interrelated problems and inability to easily communicate with La Serena staff. The other telescopes, fortunately affected less, were brought back into service within a day or two.
The Entel communications tower on Tololo was also struck, so we lost telephones, the computer link to La Serena, and the cell phone net. Communications between La Serena and Tololo were reduced to two-way radios, which hampered the Tololo repair effort. Loss of grid power on Tololo followed by over-voltage on the high-tension grid supply added to the complications. We continue to share the burden of rotating two-hour daily power cuts taking place throughout Chile in response to a drought-induced shortage of hydroelectricity. The generator is thus still required for several hours a day on Tololo.
Electrical storms occur only every few years here, and this one was undoubtedly the most severe in at least 30 years. But the large amount of repair work needed and loss of telescope time has prompted us to examine ways to both improve our immunity to lightning strikes, and our backup communications.
Alistair Walker (awalker@noao.edu)