There and back again: sharing a major instrument between hemispheres

As astronomical instruments have increased in complexity, cost and production time, sharing a major instrument between telescopes has become an attractive alternative to duplication. This requires solving technical and logistical problems of transportation, transferring operational support knowledge between on-site staffs, and developing effective responses to in-service problems at a different site. The infrared camera NEWFIRM has been operated for two years on the 4-m Mayall telescope of Kitt Peak National Observatory in Arizona. We have recently temporarily moved it to the 4- m Blanco telescope of Cerro Tololo Interamerican Observatory in Chile for a limited period of operation. We describe here our solutions to the challenges involved in relocating this major in-service cryogenic instrument, with an emphasis on "lessons learned" to date.