Malcolm G. Smith, Hugo Ochoa (AURA/NOAO/CTIO) and
Pedro Sanhueza (OPCC)

Although Cerro Tololo and Cerro Pachon are dark-sky sites, they are
the most vulnerable in Chile to the threat of light pollution.  These sites
act as a "canary in the mine" - an early warning to international astronomers
and the Chilean authorities of the need to protect this natural heritage.
The main components of the current threat to these sites are the lights from
the cities of La Serena and Coquimbo plus the nearby towns of Vicun~a
and Andacollo.

The City of La Serena has just put out a call for bids to replace and
maintain 13,000 luminaires so as to comply with DS686 - the "Norma
Luminica" or Lighting Guideline - which was promulgated in 1999 and has
a built-in grace period which is about to expire.

In order to provide a baseline reference in anticipation of this major
change, a series of panoramic views of La Serena and Coquimbo has
been photographed from the AURA campus which overlooks these
towns.  The views were taken in daylight, evening and before dawn.
Comparison of the images demonstrates the degree of city-wide
compliance with the curfew on bad lighting called for in DS686.

This "supreme decree" by the Chilean Government sets out a loose
lighting code for the 2nd (Paranal/VLT), 3rd (Las Campanas/Magellan)
and 4th (ESO-La Silla; AURA/PachonGemini-South/SOAR/Tololo/CTIO)
Regions of Chile that are of prime importance to astronomy.

The looseness of the pre-curfew code is illustrated by the extreme glare
in further images of legal, evening, sporting events viewed from the same
location.  It is hoped that many of the deficiences in the current code can
be corrected in a forthcoming revision of this Decree.