Improvement of the thermal environment around the Subaru Telescope enclosure

As the construction of the Subaru Telescope neared the end and the preparation of the first aluminum coating of the primary mirror on the ground floor of the telescope enclosure was in progress in 1997, dust particles blown into the enclosure became a serious issue. The source of the dust particles was mainly volcano cinder rocks in the immediate vicinity of the dome that were crushed through the construction activities, especially by heavy vehicle traffic around the dome. The mitigation measure proposed was to pave the immediate surrounding of the dome. The Subaru dome has a unique design with the special consideration to the airflow through the structure with a few ventilators for the best seeing condition possible. The heat retained by the pavement that may possibly cause thermals was an immediate concern. We examined several types of pavement materials to solve this problem and decided the most suitable materials and method. As a result, we paved the area using asphalt, and were able to improve seeing performance before midnight observation by painting the surface of pavement area white in 2003.