Presentation #319.01 in the session Recent Successes in Dark Skies Preservation: Flagstaff and Beyond (3).
Dark sky protection is fundamental for the concentration of large-aperture telescopes in Southern Arizona, including the LBT, MMT, Mayall and WIYN, as well as the VERITAS Cerenkov array. In addition, many moderate and small-aperture telescopes support the research and amateur communities. Many municipalities and counties look to the Pima County / City of Tucson Outdoor Lighting Code as an example for the extended metropolitan area. A decadal revision of that code is underway that addresses the technical shift from metal halide and sodium vapor to LED, including the relative visibility based on color response of the eye. Practical compromises were made among the competing interests of commercial lighting design, advertising, and dark sky protection. Lighting overlay zoning remains the guiding factor for allowable illumination levels.
Lights from the Phoenix metro area of over 4.5 million people impact all the professional observatories, but that populace feels much less sense of ownership of the State’s astronomy enterprise. The Arizona Astronomy Consortium comprises representatives from all the professional observatories; it serves as information exchange for best practices and coordinates a unified response when the State Legislature or local councils introduce measures unfavorable to astronomical sites. Past successes are harder to replicate in an anti-regulatory, business-friendly environment; continuing education about the importance of dark skies is always key.