Gemini North Engineering Shutdown Complete

Left: the A&G slice holding the Science Fold mirror (central in this picture). Right: one of two lead screws which drive the science fold into position; the spindle holder which required replacement is indicated by an arrow.

Every year it is necessary to perform maintenance on the Acquisition and Guiding (A&G) unit at the heart of each Gemini telescope. With the Gemini South maintenance shutdown successfully completed in August, Gemini North’s turn came between September 17-27. The Engineering team extracted the A&G unit from the center of the Instrument Support Structure, carried out essential preventive maintenance, and returned it to the telescope. In the course of the work, a damaged spindle holder (see figure below) on one side of the linear stage of the science fold mechanism was discovered and a replacement quickly fabricated by a machine shop in Hilo.

While work progressed on the A&G, we also performed some remedial work on instruments, which included cleaning of imaging filters in the Gemini Multi-Object Spectrograph (GMOS), extracting the unused polarimetry unit (GPOL) from the A&G, fixing the Near-Infrared Imager (NIRI), and installing a large fluid cooler as part of our energy savings program. Finally, we carried out maintenance on dome bogies and completed work on the Primary Mirror Control System. The telescope resumed operations, on schedule, on September 28.