- 1 Protection and management
- 1.1 Ownership Info Theme: Windows to the universe: Starlight, dark-sky areas and observatory sitesEntity: 59Subentity: 5Version: 2Status: PUBDate: 2013-02-17 20:00:30Author(s): Malcolm Smith with contributions by Clive Ruggles
- 1.2 Protective designation Info Theme: Windows to the universe: Starlight, dark-sky areas and observatory sitesEntity: 59Subentity: 5Version: 2Status: PUBDate: 2013-11-06 11:00:47Author(s): Malcolm Smith with contributions by Clive Ruggles
- 1.3 Means of implementing protective measures Info Theme: Windows to the universe: Starlight, dark-sky areas and observatory sitesEntity: 59Subentity: 5Version: 3Status: PUBDate: 2017-11-10 16:13:43Author(s): Malcolm Smith with contributions by Clive Ruggles
- 1.4 Existing plans Info Theme: Windows to the universe: Starlight, dark-sky areas and observatory sitesEntity: 59Subentity: 5Version: 3Status: PUBDate: 2013-11-06 11:26:57Author(s): Malcolm Smith with contributions by Clive Ruggles
- 1.5 Visitor facilities and infrastructure Info Theme: Windows to the universe: Starlight, dark-sky areas and observatory sitesEntity: 59Subentity: 5Version: 2Status: PUBDate: 2013-11-10 17:42:21Author(s): Malcolm Smith with contributions by Clive Ruggles
- 2 Monitoring
- 3 Documentation
- 4 Case Study Navigation
Of the major observatories in Chile, the AURA Observatory is currently the most threatened by the gradual encroachment of light pollution and therefore serves as a marker for gaining experience over the next two or three decades in how to protect the dark skies not only over this observatory but also over other sites in Northern Chile, including the site of the European Extremely Large Telescope (E-ELT, the largest ground based optical telescope currently planned anywhere in the world).
A CTIO study in 2004 discussed predictions for night sky brightness at Cerro Pachón, in the context of planning for the LSST. It presents the relevant numbers and several projections, depending on population growth and the success of lighting controls. The study demonstrates that with successful lighting awareness campaigns, such as that which CTIO/AURA has launched, Cerro Pachón and Cerro Tololo can continue to be prime astronomical sites for at least 3 decades even under the assumption that the dramatic population growth of the La Serena/Coquimbo conurbation (32% between 1992 and 2002) continues into the future.
That assumption may be proving to be the correct one—the rapid growth over the last 30 years of La Serena and Coquimbo is a concern. The current population is 412,586 (according to preliminary census figures for Chile released in August, 2012) and large mining projects in northern Chile have accelerated the arrival of inhabitants to the conurbation. This 27% growth over the last decade compares fairly closely with the predictions of the constant-growth model used in the CTIO study which, ten years ago, predicted a population of 425,000 for 2012. Currently 19 infrastructure projects totalling US$277,000,000 are being planned for this conurbation.
This rapid growth is in the context of half of humanity now living in cities. According to National Geographic Magazine (December 2011 issue, pp. 138-139), in 1800 there were only three cities of one million or more, in 1900 16 such cities and in 2010 442 of them, with 21 having more than 10 million and several exceeding 20 million. Thus the earlier assumptions about city development made in the CTIO study—that the rapid-growth model for La Serena and Coquimbo was unlikely to continue for more than two decades—remain uncertain.
With regard to street lighting, the recent increase in population in La Serena/Coquimbo has increased the number of vehicles. Traffic licences for La Serena/Coquimbo are increasing at a rate of 9.2% each year (compared with Chile’s national rate of increase, which has reached 7.5%). There are currently 90,000 vehicles in La Serena. The Ministry of Transport expects this number to double by the year 2020—about the time that LSST will begin operations.
It is fortunate indeed that light pollution control was begun in earnest in Chile 20 years ago. It is also particularly fortunate that most of the current conurbation is shielded by a range of coastal mountains which still block a direct view of most of the conurbation from Cerro Tololo and Cerro Pachón.
Fig. AO.6: The night sky at Cerro Tololo (Photograph: Arturo Gomez/NOAO/AURA/NSF)
Pressure continues to develop a bi-oceanic corridor through Argentina, under the Andes (the Agua Negra tunnel) and down the Elqui valley near the AURA observatory – in support of trade between Brazil and China. It is important to learn the lessons provided by Los Angeles plus the Palomar and Lick Observatories in the USA. Los Angeles grew in a hundred years from an urban center about 2/3 the size of the current La Serena-Coquimbo conurbation to a city of 5,000,000 people. Protection of the northern Chilean sites needs continued attention—we cannot afford to be complacent.
When the El Totoral area was purchased by AURA, the land supported a number of subsistence farmers and goat herders. They were allowed to continue to live on the reserve after it was purchased by AURA and have gradually been leaving voluntarily for more lucrative jobs in the nearby towns.
As a result of the departure of most of its human inhabitants and a policy combining environmental protection with benign neglect on the part of the Observatory, the property sees little human activity except for the roads and relatively small areas on the tops of Cerro Tololo and Cerro Pachón. As a result, much of the reserve is gradually returning to its natural state. Many native species of plants and animals, long thought in danger of extinction, are now returning. The last half of the trip to Tololo is an excellent opportunity to see a reasonably intact Chilean desert ecosystem. During the first portion of the journey, to a few km beyond El Totoral, the effect on the environment of humans, bad farming practices and the remaining goats is easily seen. That damage will take many years to heal.
Cerro Tololo is open to the public every Saturday, summer and winter, weather permitting. For safety and security reasons, the number of visitors on any given day is limited to two groups of 40 people. One group meets at the gatehouse at 9am and the other at 1pm. Because the number of visitors is limited, advance reservations are essential. During the tourist season from mid-December to March, reservations must be made several weeks in advance. Permits must be picked up in La Serena before proceeding to the mountain. Access to the mountain is by private vehicles only. There is no public transportation.
Permits are free and may be obtained from the Reception Desk in La Serena. Tours are conducted at no charge by a professional guide. Total elapsed time from leaving the gatehouse until returning to the highway is approximately three hours.
AURA has worked with local tourism agencies and municipalities in support of the development of 7 public observatories. This successful program has relieved the pressure on the AURA observatory, which is not open to the public at night, while creating employment and educational opportunities for local people. The Coquimbo Region is now known as La Region Estrella largely as a result of these initiatives.
For more information on public access to CTIO, click here. As the next image shows, not only human visitors are interested in visiting the summit of Cerro Tololo …
Fig. AO.7: The Cerro Tololo dome reflected in the eye of a condor (Photograph: Arturo Gómez/NOAO/AURA/NSF)
Number of inhabitants
See “Developmental pressures” and “Environmental pressures” above.
Protection and management
The entire 34,491ha (344.9km²) site is owned by AURA, the Association of Universities for Research in Astronomy. AURA is recognized by the Chilean Government as an accredited International Organization, with a variety of diplomatic privileges. The stakeholders are the 40 international member institutes of AURA Inc.
The El Totoral Reserve around Cerro Tololo and Cerro Pachón has been declared ’of Scientific Interest‘ by the Chilean Government, which protects it from incursion by mining interests.
The Region of Coquimbo is one of three Regions in northern Chile where artificial lighting will be governed by the requirements of Supreme Decree 43/2013—already signed by the President of Chile on 3 May 2013 and which will come into effect on 3 May 2014—as an updated revision of Supreme Decree 686/1998 (the ’norma lumínica‘). This protects against light pollution.
Means of implementing protective measures
Any mining activity within this area, including prospection work, would require the written permission of the President of the Republic of Chile. The buffer zone is protected from mining operations via a formal program of constant monitoring of requests for mining activity.
On the property, AURA voluntarily complies with and exceeds all environmental protection requirements of the Chilean government, including of course, the norma luminica.
Outside the property, AURA carries out education work via its membership of the consortium which supports the Office for the Protection of the Quality of the Skies of Northern Chile (OPCC) and through activities in local schools. The OPCC has the mission to carry out public education and to assist the Chilean government in the protection of this natural resource.
Under the supervision of the Superintendent’s Office of Electricity and Fuel (SEC, Chile) and local municipalities, about 50% of all street lights in the Region of Coquimbo have now been modified or replaced in order to comply with the requirements of the norma luminica.
The observatory has formed a network of 200+ schools and support organization in collaboration with the Municipality of La Serena, the University of La Serena and the national Libraries, Archives and Museums directorate (DIBAM). The Coquimbo Region has developed an extensive astro-tourism initiative which has flourished because of the contrast between the polluted skies of much of Europe, Japan and the USA and the skies as seen through the Windows to the Universe. Seven public and private observatories have opened in the Region in response to demand from networks of schools and from tourists (see http://www.ctio.noao.edu/noao/node/1147). Recognizing this natural and cultural heritage, the motto of the Coquimbo Region of Chile is now ’Coquimbo—the Star Region‘.
AURA has been working via the OPCC with the Chilean Ministry of the Environment to develop an updated version of the Norma Lumínica. This will limit proliferation of blue-rich Light Emitting Diodes. The blue region of the optical spectrum is currently without significant pollution (Kriscuinas et al. 2010), even from Cerro Tololo looking at the sky directly over the La Serena/Coquimbo conurbation (largely as a result of using sodium lighting fixtures). An additional advance under the new Norma will be to limit the amounts of light allowed and to have external lighting upgraded to full cut-off (full shielding above the horizontal).
The longer-term aim is to have the Norma Lumínica upgraded to a Chilean law, rather than a set of environmental rules.
Visitor facilities and infrastructure
The Coquimbo Region has developed an extensive astro-tourism initiative which has flourished because of the contrast between the polluted skies of much of Europe, Japan and the USA and the skies as seen through the Windows to the Universe. Seven public and private observatories have opened in the Region in response to the demand from networks of schools and from tourists: see http://www.ctio.noao.edu/noao/content/astro-tourism-chile. Recognizing this natural and cultural heritage, the motto of the Coquimbo Region of Chile is now ’Coquimbo—the Star Region‘.
Indicators for measuring state of conservation
Measurements of broad-band magnitudes per square arcsecond alongside regular photography provide a first-order guide to the source and extent of light pollution sufficient for most purposes including setting local priorities for protective action. The zodiacal light (sunlight reflected off dust in the plane of our solar system) is easily seen from first-class dark-sky locations, but not from even fairly mildly polluted sites. Major observatories, such as those included in the Windows to the Universe, usually support studies every few years to check the status of light pollution from their surroundings. An effort to introduce international, continuous monitoring on an intercomparable basis at many sites is currently being attempted by the International Dark Sky Association; the Cerro Tololo site has been used for one year as one of three beta test sites for this work, which will take and send measurements taken automatically each night for processing and display on the web, in a graphical form, readily accessible to the public. One plan is to have one detector pointed at the zenith, the other pointed over the source of most serious local light pollution, at each of the Windows to the Universe.
Fig. AO.8: The setting Zodiacal Light as seen looking SW from Cerro Tololo. a (above): With the Zodiacal Light still quite high in the sky. b (below): After the Zodiacal Light has set. (Photographs: Roger Smith / CTIO)
Fig. AO.9: Images based on work done for the World Atlas of Artificial Night-Sky Brightness by P. Cinzano, F. Falchi (University of Padova) and C.D Elvidge (NOAA National Geophysical Data Center, Boulder), published in the Monthly Notices of the Royal Astronomical Society in 2001. a (above): Northern Chile. b (below): The world. Reproduced by permission of Oxford University Press
Measuring the night sky brightness in order to quantify contamination in the directions in which we are interested (e.g. zenith distances less than 60 degrees) is difficult at world-class sites owing to the necessity of measuring an effect that may be only 1-2 % of the sky brightness. Additionally, interpretation of the results may not be straightforward. The natural brightness varies on timescale of minutes to years with amplitudes of several tenths of a magnitude (Patat 2006). The choice of sky position is important. Lavasseur-Regourd and Dumont (1980) model the increase in background as the ecliptic plane (and its zodiacal light) is approached. In the V band the effect is 0.3 magnitudes at ecliptic latitude 0 and falls by roughly 0.05 mag for each 10 degree increase in ecliptic latitude.
Two of the most recent monitoring papers for Cerro Tololo are Kriscuinas et al. (2007; 2010). Cerro Tololo is closer to La Serena-Coquimbo and Vicuña than Cerro Pachon and is roughly estimated to suffer 65% more light contamination than Cerro Pachon. It will be necessary to analyze a lot more data before we have any hope of measuring long-term trends in light pollution over Cerro Tololo. It is particularly important to support efforts to fund a second epoch of the World Atlas of the Artificial Night Sky Brightness (Cinzano et al. 2001)—see Figures AO.9a (the world) and AO.9b (Chile) reproduced from that Atlas.
Significant modelling extensions have recently been reported by Cinzano and Falchi (2012). However, more computing power will be needed to include the beneficial screening effect of coastal mountains which protect the summits of Cerro Tololo and Cerro Pachón from a direct view of most of the lights in the La Serena/Coquimbo conurbation.
Another approach is being followed based on taking many less precise, simple measurements of the zenith sky brightness using Sky Quality Meters closer to the cities and other major sources of light pollution. The Globe at Night program involves citizen scientists from the general public in this increasingly useful, world-wide monitoring effort—as explained at the program website.
Cinzano, P., Falchi, F., & Elvidge, C.D., 2001. The first world atlas of the artificial night sky brightness. Monthly Notices of the Royal Astronomical Society 328, 689-707.
Cinzano, P., Falchi, F., 2012. The propagation of light pollution in the atmosphere. Monthly Notices of the Royal Astronomical Society 427, 3337-3357
Krisciunas, K., Semler, D.R., Richards, J., Schwarz, H.E., Suntzeff, N.B., Vera, S., & Sanhueza, P., 2007. Optical Sky Brightness at Cerro Tololo Inter-American Observatory from 1992 to 2006. Publications of the Astronomical Society of the Pacific, 119, 687-696.
Krisciunas, K., Bogglio, H., Sanhueza, P., & Smith, M.G., 2010. Light pollution at high zenith angles, as measured at Cerro Tololo Inter-American Observatory. Publications of the Astronomical Society of the Pacific, 122, 373-377.
Lavasseur-Regourd, A.C. & Dumont, R., 1980. Absolute photometry of zodiacal light. Astronomy and Astrophysics, 84, 277-279.
Marín, C. & Jafar, J. 2008. Starlight: a Common Heritage. UNESCO/IAU/Instituto de Astrofísica de Canarias.
Patat, F., 2008. The dancing sky: 6 years of night-sky observations at Cerro Paranal. Astronomy and Astrophysics, 481, 575-591
Addere Ltda, 2012. Estudio Capacidades y Oportunidades para la Industria y Academia en las Actividades Relacionadas o Derivadas de la Astronomía y los Grandes Observatorios Astronómicos en Chile. Informe No. 3.
Centro de Estudios Avanzados en Zonas Arídas, 2013. Pionera actividad busca potenciar el desarrollo turístico como promotor del conocimiento científico en el Parque Nacional Fray Jorge.
Ministerio del Medio Ambiente, 2013. Establece norma de emissión para la regulación de la contaminación lumínica, elaborada a partir de la revision del decreto No. 686, de 1998, del Ministerio de Economía, Fomento y Reconstrucción. Biblioteca del Congreso Nacional de Chile – Legislación chilena. Decreto 43. Fecha Publicación: 3 May 2013. Inicio Vigencia: 3 May 2014.
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Windows to the universe: Starlight, dark-sky areas and observatory sites