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C. Foltz (MMT Observatory), D. Brocious (Whipple Observatory)
Tucson, Arizona, and surrounding Pima County, first adopted outdoor lighting codes to protect dark skies in 1972. At that time, the observatory sites at Mount Hopkins, Kitt Peak, and to a lesser extent Mounts Lemmon and Bigelow, were well away from the urban core and could be protected by shielding lights and gradually replacing mercury vapor sources with low pressure sodium lamps.
Although the code has been modified several times to reflect changes in lighting technology and population increase, the 200l code is a marked change in approach. With urban and suburban sprawl coming ever closer to the dark observing sites, the code now incorporates lumen caps or limits on the amount of lighting that may be installed per unit area. The amount varies with proximity to the observatories: more light in the areas more distant from the observatories, and less light permitted nearer the observatories. Although some other jurisdictions, notably Flagstaff, Arizona, have used this method with success for some time, the idea met with resistance in southern Arizona. To allay fears and demonstrate how lighting limits would work in practice, more modest lumen caps have been implemented. After a period of familiarization, we expect to able to modify the lighting limits for better dark sky protection.
The author(s) of this abstract have provided an email address for comments about the abstract: brocious@base.sao.arizona.edu