International Conference on Light Pollution Theory, Modelling and Measurements

Mai 26 – 28, 2015, Jouvence, Québec, Canada

Book of Abstracts

Credits: NASA, post­processing Rémi Boucher

Organised by: Cégep de Sherbrooke – Faculty of Mathematics Physics and Informatics, Comenius University in Bratislava ­ ICA, Slovak Academy of Sciences

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Scientific Committee Dr Thomas Posch, Institut für Astrophysik, Universitätssternwarte Wien, Austria Dr Chun Shing Jason Pun, Department of Physics, The University of Hong Kong, China Dr Miroslav Kocifaj, Faculty of Mathematics Physics and Informatics, Comenius University in Bratislava, Slovakia and ICA, Slovak Academy of Sciences, Bratislava, Slovakia. Dr Martin Aubé, Département de Physique, Cégep de Sherbrooke, Canada

Local Organizing Committee

Martin Aubé, Cégep de Sherbrooke Johanne Roby, Cégep de Sherbrooke Miroslav Kocifaj, Faculty of Mathematics Physics and Informatics, Comenius University in Bratislava Olivier Domingue, Cégep de Sherbrooke

Credits: Guillaume Poulin

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LPTMM 2015 This meeting focus on recent advances in scientific investigations on light pollution and its impact on astronomical observations. The study of light pollution is undergoing a renaissance due to development of high performance computers that can significantly reduce the time needed for more accurate numerical simulations. Theoretical solutions, numerical modeling, and field campaigns represent diverse approaches to the analysis, prediction, and characterization of light pollution levels and behaviour. The meeting aim is to bring together the experts in that field to discuss the current state of the art and to formulate new research directions. The conference aim to facilitate a more intensive development in this field of research. Topics:

Theoretical concepts of modelling light pollution Numerical tools and simulation experiments Effects of atmospheric aerosols and obstacles on light pollution Impact of spectral characteristics of light sources and reflecting surfaces Observational techniques, data, and products Design and evaluation of dark sky friendly lighting technologies

The meeting takes place at Jouvence meeting center, Québec, Canada.

For further information see the conference home page http://lptmm.org/

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Sponsors

Centre de recherche en astrophysique du

Québec (CRAQ)

Lekla inc.

International Dark Sky Association

Unihedron Inc.

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Sherbrooke innopole

International Dark Sky Association ­ Québec

Royal Astronomical Society of Canada Société royale d’astronomie du Canada

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Programme

Session talk Time Author and Title / Event

Duration Tuesday, May 26 08:00 Bus departure from Grand Times hotel (Sherbrooke) ­ Transport provided by conveners

1:00:00 08:30 On site registration & room check in 0:15:00 09:30 Welcome words from officials (IDA J. Barentine + IDA Québec M. Pecingina) 0:20:00 09:45 Opening talk by local organizers – Martin Aubé, Johanne Roby, and Olivier Domingue 0:30:00 10:05 Sébastien Giguère (Canada) ­ Cosmic Rhythms Movie 0:30:00 10:35 Coffee break ­ Rose des vents

0:30:00 11:05 Rémi Boucher & Guillaume Poulin (Canada) – Photography as a way to bring awareness tolight pollution

0:30:00 11:35 Key Speaker: Chun Shing Jason Pun (Hong Kong) ­ Night Sky Brightness Measurements: Review and Prospects

1:30:00 12:05 Lunch buffet ­ Crémaillère

0:05:00 A & B 13:35 Theoretical concepts of modeling the light pollution & Numerical tools and simulation

experiments – Chairman: Jason Pun (Hong Kong)

0:30:00 1 13:40 Key speaker: Stefan Noll (Austria) ­ The origin and variability of the natural night­sky radiation

0:20:00 2 14:10 D.Duriscoe ­ Tracking sky quality over time with a simplified model of all­sky artificial sky glow derived from VIIRS Day/Night Band data

0:20:00 3 14:30 A. Domény ­ The effect of lighting reconstructions of some Hungarian cities 0:20:00 4 14:50 H. Netzel ­ Modelling of light pollution over Poland using high resolution data 0:20:00 15:10 Coffee break ­ Rose des vents

2:00:00 15:30 Group photo – Networking period ­ Free time ­ sports ­ rooms available to the

attendees 2:00:00 17:30 Concert in Girouette by Moucheté (Jazz manouche) Soft drinks and snacks provided 2:00:00 19:30 Dinner – Reception ­ Crémaillère 2:00:00 21:30 Informal discussions around Poudrerie fireplace – drinks and snack provided

Wed, May 27 1:10:00 07:30 Breakfast ­ Crémaillère

0:05:00 C 08:40 Impact of spectral characteristics of light sources, aerosols, obstacles and reflecting

surfaces – Chairman: Christopher Kyba (Germany)

0:30:00 1 08:45

Key speaker: Martin Aubé (Canada) ­ How the sky brightness depends on wavelength, aerosol content, ground reflectance, lamps photometry, terrain and obstacles.

0:20:00 2 09:15 K. Baibakov ­ Quantifying night­time aerosol optical depth using star­ and moon­photometry

0:20:00 3 09:35 Z. Kollath ­ In situ estimation of atmospheric properties for light pollution measurements and modeling

0:20:00 09:55 Coffee break ­ Rose des vents 0:20:00 4 10:15 A. Sanchez de Miguel ­ Diffuse light on satellite imagery and sky brightness

0:20:00 5 10:35 H. Solano Lamphar ­ Retrieval of urban emission function from sky glow data: an experimental approach

0:20:00 6 10:55 J. Roby ­ Manage lighting applications with three spectral indices

0:20:00 7 11:15 A. Morin­Paulhus ­ An Online Tool to Get Complete Spectral Information and Potential Impacts for a Large Variety of Commercial Lamps

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0:30:00 8 11:35 Elevator pitch (posters and sponsors gold) 1:30:00 12:05 Lunch buffet ­ Crémaillère

0:05:00 D 13:35 Design and evaluation of dark sky friendly lighting technologies – Chairman: Olivier

Domingue (Canada) 0:20:00 1 13:40 R. Dick ­ Biological Thresholds for Nocturnal Light Compared to LED Characteristics 0:20:00 2 14:00 A. Haenel ­ Light Sources for protecting the night 0:20:00 3 14:20 K.l. Pendoley ­ Light measurement and modelling requirements of the biological sciences 0:20:00 4 14:40 Coffee break­ Rose des vents 0:05:00 E 15:00 Observational techniques, data, and products 1 – Chairman: Dan Duriscoe (USA)

0:30:00 1 15:05 Key Speaker: Chris Kyba (Germany) ­ Skyglow phenomenology: Bridging the gap between experiment and theory

0:20:00 2 15:35 B. Wren ­ Assessment of light pollution impacts from oil and gas developments

0:20:00 3 15:55 S. Ribas ­ Light Pollution studies on Montsec Reserve using the new Catalan Light Pollution Network

0:20:00 4 16:15 V. Tilve ­ Determining the continuous all­sky night brightness distributions from discrete sets of localized measurements

0:20:00 5 16:35 K.P. Tong ­ Angular and temporal dependence of artificial light at night upwelling towards VIIRS­DNB

1:20:00 6 16:55 Networking period ­ Free time 1:20:00 P 18:15 Poster session – apéritif, snacks provided ­ Poudrerie living room

1 S. Bara (V. Rua) ­ The Galician Night Sky Brightness Monitoring Network 2 S. Bara (V Rua) ­ Modal approaches for light pollution measurement and modeling

3 W. Blanchette ­ A moon spectrometer to infer the aerosol optical depth and sky brightness during the night

4 S. Houle ­ A satellite based intrusive light model

5 J. Puschnig (A. Hanel) ­ Comparing the Night Skies over Stockholm/Sweden and Vienna/Austria

6 C.E. Walker ­ Characterizing Night Sky Brightness In and Around Tucson and Nearby Observatory Mountaintops

7 M. St­John ­ Implementing clouds into the night sky radiance model Illumina 2:00:00 19:35 BBQ dinner on lake shore 2:00:00 21:35 Informal discussions around Poudrerie fireplace – drinks and snack provided

Thu, May 28 1:10:00 07:30 Breakfast ­ Crémaillère

0:05:00 E 08:40 Observational techniques, data, and products 2 – Chairman: Alejandro Sanchez de Miguel (Spain)

0:30:00 7 08:45 Key speaker: Kim Baugh (USA) ­ The VIIRS Day/Night Band: Creating the Next Generation of Global Remotely­Sensed Nighttime Lights Products 0:20:00 8 09:15 C. Walker ­ Intercomparing Methods of Night Sky Brightness Measurements 0:20:00 9 09:35 D. Duriscoe ­ Use of the SQM­L for all­sky light pollution measurement 0:20:00 10 09:55 S. Ribas ­ Intercomparison campaigns of Night Sky Brightness measuring techniques 0:20:00 11 10:15 Coffee break ­ Rose des vents 1:30:00 10:35 Networking period ­ Free time ­ room checkout 1:30:00 12:05 Lunch buffet ­ Crémaillère 0:05:00 E 13:35 Observational techniques, data, and products 3 – Chairman: Salvador Ribas

0:20:00 1 13:40 M. Pravettoni ­ Measuring the darkness with a solar simulator: indoor calibration of sky brightness meters

0:20:00 2 14:00 P.D. Hiscocks ­ Calibrated Measurements of Luminance and Sky Glow with a Digital Camera

0:20:00 3 14:20 C.W. So (J. Pun) ­ Case studies of remote sensing and field experiments on the contribution of artificial light sources to the night sky observed in Hong Kong

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0:20:00 4 14:40 H. Spoelstra ­ Night time spectral behavior of the SQM 0:20:00 5 15:00 A. Mohar ­ Sky Quality Camera as a quick and reliable tool for light pollution monitoring 0:20:00 15:20 Coffee break ­ Rose des vents 0:10:00 15:40 Concluding remarks ­ LPTMM 2017 0:20:00 15:50 Open discussions

1:00:00 16:10

Focussed meeting ­ Establishing links between measurements and models to improve collaborations (sharing data, common data storage platform and format, useful model

output for observers, etc.) Moderator: Chris Kyba 0:05:00 17:10 Free time 0:30:00 17:15 Transport to Grand Times hotel (Sherbrooke) ­ Transport provided by conveners 0:30:00 17:45 Arrival in Grand Times hotel (Sherbrooke)

Useful informations

wifi id : jouvence password : there is no password

The timetable will be strictly observed by the chairmen. Prior to your session, upload your files on the conference laptop during a

coffee break with the help of our technical staff. Posters must be installed before 18h15 on May 27 and have to be removed

before 13h on May 28. Your room will be available at 15h30 on May 26. You will be asked to let

your luggage in the conference room before that time. You will have to quit your room before 11AM on May 28. You will be

asked to let your luggage in the conference room after that time. Conference room will be locked during lunches. Always keep your bracelet with you to get access to the meals, coffee

breaks, and free sports equipment borrowing. Keep your name badge to get access to the conference room and other

activities. Access to spa and sauna is free, but you need to reserve at the front desk. Camp fires, drinks and snacks will be at Poudrerie fireplace. In case of

rain, snacks and drinks will be served in Poudrerie lounge. The concert will be given in the Girouette building on May 26 Dining room is in the same building as the reception and the meeting room There are fresh fruits available at any time in the dining room.

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Site map

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Content 1­ Cosmic Rhythms 2­ Photography as a way to bring awareness to light pollution 3­ Night Sky Brightness Measurements: Review and Prospects 4­ Modal approaches for light pollution measurement and modeling 5­ The Effect of Lighting Reconstructions of Some Hungarian Cities 6­ Tracking Sky Quality Over Time With a Simplified Model of All­Sky Artificial Sky Glow Derived from VIIRS Day/Night Band Data 7­ Theoretical and Numerical Approaches to Modeling Skyglow: RTE, SOS, and N­stream Approximation 8­ Modelling of Light Pollution Over Poland Using High Resolution Data 9­ The Origin and Variability of the Natural Night­Sky Radiation 10­ How the Sky Brightness Depends on Wavelength, Aerosol Content, Ground reflectance, Lamps Photometry, Terrain and Obstacles 11­ Quantifying Night­Time Aerosol Optical Depth Using Star­ and Moon­Photometry 12­ In Situ Estimation of Atmospheric Properties for Light Pollution Measurements and Modeling 13­ Manage Lighting Applications with Three Spectral Indices 14­ An Online Tool to Get Complete Spectral Information and Potential Impacts for a Large Variety of Commercial Lamps 15­ Diffuse Light on Satellite Imagery and Sky Brightness 16­ Retrieval of Urban Emission Function from Sky Glow Data: an Experimental Approach 17­ Angular and Temporal Dependence of Artificial Light at Night Upwelling Towards VIIRS­DNB 18­ Biological Thresholds for Nocturnal Light Compared to LED Characteristics 19­ Light Sources for Protecting the Night 20­ Light Measurement and Modelling Requirements of the Biological Sciences 21­ Determining the Continuous All­Sky Night Brightness Distributions from Discrete Sets of Localized Measurements 22­ The VIIRS Day/Night Band: Creating the Next Generation of Global Remotely­Sensed Nighttime Lights Products 23­ Use of the SQM­L for All­Sky Light Pollution Measurement 24­ Calibrated Measurements of Luminance and Sky Glow with a Digital Camera 25­ Skyglow Phenomenology: Bridging the Gap Between Experiment and Theory 26­ Measuring the Darkness with a Solar Simulator: Indoor Calibration of Sky Brightness Meters 27­ Light Pollution Studies on Montsec Reserve Using the New Catalan Light Pollution Network 28­ Intercomparison Campaigns of Night Sky Brightness Measuring Techniques 29­ Case Studies of Remote Sensing and Field Experiments on the Contribution of Artificial Light Sources to the Night Sky Observed in Hong Kong 30­ Night Time Spectral Behavior of the SQM 31­ Assessment of Light Pollution Impacts from Oil and Gas Developments 32­ The Galician Night Sky Brightness Monitoring Network 33­ A moon Spectrometer to Infer the Aerosol Optical Depth and Sky Brightness During the Night 34­ A satellite Based Intrusive Light Model 35­ Comparing the Night Skies over Stockholm/Sweden and Vienna/Austria 36­ Characterizing Night Sky Brightness In and Around Tucson and Nearby Observatory Mountaintops 37­ Sky Quality Camera as a Quick and Reliable Tool for Light Pollution Monitoring 38­ Implementing Clouds into the Night Sky Radiance Model Illumina 39­ Intercomparing Methods of Night Sky Brightness Measurements

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Introductory talks

1­ Cosmic Rhythms Sébastien Giguère1

1 ASTROLab du parc national du Mont­Mégantic, Notre­Dame­des­Bois J0B 2E0, Canada tel: +1 819 888 2941 ext 223e­mail: giguere.sebastien@sepaq.com

Abstract

Short HD film Cosmic Rhythms invites you into a fascinating voyage through space and time. Explore the different timescales of the cosmos and discover your place in the history of the Universe!

2­ Photography as a Way to Bring Awareness to Light Pollution Remi Boucher1 and Guillaume Poulin1

1 ASTROLab du parc national du Mont­Mégantic, Notre­Dame­des­Bois J0B 2E0, Canada

tel: +1 819 888 2941 ext 329, e­mail: boucher.remi@sepaq.com tel: +1 819 888 2941ext 269, e­mail: poulin.guillaume@sepaq.com

Abstract

Images can be powerful tools for monitoring and measuring light pollution. Satellite imagery, aerial survey and all­sky imaging all provide great visual representation of the sources of light pollution or its effects on the night sky. Photography can also be used to show the extent of the problematic and bring awareness with dramatic images like the ones sent from the astronauts on the International Space Station. But down here on Earth, photography of dark­sky places also provide a way for people to discover or rediscover the beauty of the night sky that an increasing number of people may have never experiences or have lost connection with. If we want people to fight against light pollution, we need to show them the beauty of the night.

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Scientific Contributions

3­ Night Sky Brightness Measurements: Review and Prospects Chun Shing Jason Pun1

1 Department of Physics, The University of Hong Kong, Pokfulam, Hong Kong tel: +852 2859­1962, fax: +852 2559­9152, e­mail: jcspun@hku.hk

Abstract

Measurements of the night sky brightness affected by skyglow originated from artificial lighting provide an effective way to measure the extent of light pollution. In this talk I will present a review of the techniques and methods involved, ranging from traditional astronomical photometry to visual limiting magnitude surveys from citizen scientists. The field underwent a major change in recent years with the advancement of small, portable, and easy­to­use light meters which can deliver night sky brightness measurements continuously with fairly good accuracy (~0.1 mag arcsec­2), one of which being the Sky Quality Meter (SQM). I will discuss some case studies of using SQM to establish long­term monitoring networks to study the effects of various artificial, meteorological, and astronomical factors on the observed night sky. I will conclude with the future prospects of night sky brightness measurements, in particular on concepts to develop a global monitoring network to study the impacts of light pollution.

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4­ Modal Approaches for Light Pollution Measurement and Modeling Salvador Bará,1 Víctor Tilve,2 and Josefina F. Ling2

1 Optics Area, Dept. of Applied Physics, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain

2 Astronomical Observatory "R.M. Aller", Dept. of Applied Mathematics, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain.

tel: +34 881813525, e­mail: salva.bara@usc.es

Abstract An all­sky night brightness distribution is a real function defined in the two­dimensional domain of directions of the upper hemisphere. It can be described either locally, i.e., specifying its values at a given set of spatial directions, or modally i.e., specifying the coefficients of its expansion as a series of orthonormal basis functions. In this communication we describe the fundamentals of the modal approach and explore some of the possibilities that modal descriptions provide for light pollution measurement and modeling.

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5­ The Effect of Lighting Reconstructions of Some Hungarian Cities Anita Dömény,1 and Zoltán Kolláth1,2

1 University of West Hungary, Savaria Campus, Károlyi Gáspár tér 4, 9700 Szombathely, Hungary 2 MTA CsFK Konkoly Observatory, Konkoly Thege út 15­17, 1121 Budapest, Hungary,

tel: +36 20 9721420, e­mail: kollath.zoltan@ttk.nyme.hu

Abstract In a recent paper (Kolláth & Kránicz 2014, JQSRT 139,27), we presented a test of the feasibility of urban sky glow inversion method based on Monte Carlo radiative transfer modeling of the propagation of artificial lights in the atmosphere. An application of our model calculations is to predict the changes of sky quality if different lighting systems are used. The public lighting system has been remodeled in several Hungarian cities. In some cases the majority of the old luminaries were fitted with high pressure sodium lamps and they were replaced with white LED lighting with a typical correlated color temperature of about 4500 K. Therefore, these reconstruction works provide a testbed for our methods in measurements and modeling. We measured the luminance of the light domes of selected cities by DSLR photometry before and after the reconstruction. Both the photopic and scotopic sky brightness was compared to provide a view on possible environmental effects of the lighting changes. Thanks to the full cut off design of the new lighting fixtures we obtained a slight decrease even in the scotopic luminance of the sky dome of a tested city. However, we have to note that this positive change is the result of the bad geometry (large ULOR) of the previous lighting system. We also demonstrate that significant improvements of the light pollution effects of the lighting could be reached with light sources with lower CCT or amber LED based systems. Our parallel measurements and radiation transfer calculations clearly demonstrate the importance of full cutoff lighting (ULOR=0) when white light sources are used. The imaging photometry of sky glow together with the radiation transfer modelling provides an objective method to qualify lighting systems and the remodelling of city lighting. possibilities that modal descriptions provide for light pollution measurement and modeling.

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6­ Tracking Sky Quality Over Time With a Simplified Model of All­Sky Artificial Sky Glow Derived from VIIRS Day/Night Band Data

Duriscoe, Dan M.,1 Baugh, Kimberly E.,2 and Elvidge, Christopher D.,2 1 Night Skies Program, U.S. National Park Service, Bishop, CA, U.S.A

2 Earth Observation Group (EOG), University of Colorado­ CIRES, NOAA National Geophysical Data Center, Boulder, Colorado, U.S.A.

3 Earth Observation Group (EOG), NOAA National Geophysical Data Center, Boulder, Colorado, U.S.A.

tel: +1 760 872 5044, e­mail: dan_duriscoe@nps.gov

Abstract The VIIRS Day/Night Band database from the Suomi NPP orbiting satellite provides a valuable tool for tracking changes in the upward radiance from nighttime lights over the entire Earth. Cloud­free composites of these data are now produced monthly, and may be used to predict impacts to night sky quality over time at any given location. We present a simplified method using geographic analysis tools to predict the average artificial sky luminance over the hemisphere of the sky, expressed as a ratio to a natural baseline condition, based upon the relation between sky glow brightness as seen by the observer and the distance to the light source ("Walker's Law"). Selected locations, for which recent ground­based all­sky data of sky brightness exist, are examined, with the surface observations used for calibration of the values obtained from the Walker's Law model.

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7­ Theoretical and Numerical Approaches to Modeling Skyglow: RTE, SOS, and N­stream Approximation

Miroslav Kocifaj,1,2 1 Faculty of Mathematics, Physics, and Informatics, Comenius University, Mlynská dolina, 842 48

Bratislava, Slovakia 2 ICA, Slovak Academy of Sciences, Dúbravská Road 9, 845 03 Bratislava, Slovakia, e­mail:

kocifaj@savba.sk tel: +421­2­59309293, fax: +421­2­54773548, e­mail: kocifaj@savba.sk

Abstract

Currently, the study of diffuse light of a night sky is undergoing a renaissance due to the development of inexpensive high performance computers which can significantly reduce the time needed for accurate numerical simulations. Apart from targeted field campaigns, numerical modeling appears to be one of the most attractive and powerful approaches for predicting the diffuse light of a night sky. However, the modeling of realistic night­sky radiances over any territory and under arbitrary conditions is a complex problem that is difficult to solve. In this study we introduce 3 distinct approaches to modeling the light propagation through a turbid stratified atmosphere. Two of them, specifically Eddington’s two­stream approximation and the method of radiative transfer equation (RTE) are well applicable for diffusely populated areas with almost homogeneous distribution of light sources. The method of successive orders of scattering (SOS) can be also applied to sparsely and heterogeneously distributed light sources. The principles, computational results, strengths and weaknesses of the discussed methods will be given in the full text paper.

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8­ Modelling of Light Pollution Over Poland Using High Resolution Data Henryka Netzel,1 dr Paweł Netzel2

1 Institute of Astronomy, University of Wroclaw, Poland 2 Space Informatics Lab, University of Cincinnati, USA

tel: +48 661726215, e­mail: henia@netzel.pl

Abstract In 1976 Berry introduced simple mathematical model of artificial night sky brightness (Light Pollution in Southern Ontario, JARSC, vol. 70, No. 3, 1976) and created map of light pollution for Southern Ontario achieving resolution of 8 kilometers. The original model was recalibrated using observational data collected in Lower Silesia, Poland, and used to create high resolution map of night sky brightness for Poland – 50 meter resolution. In the original model Berry calculated light pollution caused by cities regarded as single points. Significant improvement was to treat each cell in the raster map of the region as a ‘city’ in Berry’s model. Population of each cell was estimated using dasymetric modelling. This improvement was crucial to obtain detail structures of sky brightness, but it did not complicate calculations. The GRASS GIS software was used in the analysis. The results nicely fit observational data.

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9­ The Origin and Variability of the Natural Night­Sky Radiation S. Noll1, S. Kimeswenger2,1, W. Kausch3,1, A.M. Jones4,1, and S. Unterguggenberger1

1 Institute for Astro­ and Particle Physics, University of Innsbruck, Technikerstr. 25/8, 6020 Innsbruck, Austria

2 Instituto de Astronomía, Universidad Católica del Norte, Avenida Agamos 0610, Antofagasta, Chile 3 University of Vienna, Department of Astrophysics, Türkenschanzstr. 17, 1180 Vienna, Austria 4 Max Planck Institute for Astrophysics, Karl­Schwarzschild­Str. 1, 85748 Garching, Germany

tel: +43 512 507 52044, fax: +43 512 507 52099, e­mail: stefan.noll@uibk.ac.at

Abstract The radiation of the cloud­free natural night sky is caused by different processes with contributions depending on the wavelength, line of sight, time, and location. Non­terrestrial direct light comes from stars, the Moon, planets, and interplanetary dust. Except from the former, all these radiation sources are essentially based on scattered sunlight. The non­terrestrial radiation is absorbed and scattered by molecules and aerosol particles in the Earth's atmosphere. This leads to diffuse radiation components, which contribute to the so­called sky background. The atmosphere also emits directly. In the infrared, this is thermal radiation from molecules like water or carbon dioxide. The radiation mainly originates from low altitudes, where the molecular concentrations are high. In the optical and near­infrared regime, the atmospheric emission is related to the mesosphere and lower thermosphere, especially altitudes between 80 and 110 km. This so­called airglow is caused by the non­thermal line radiation of hydroxyl, molecular oxygen, atomic oxygen, sodium, and other species. There is also a poorly understood continuum component. Airglow is mostly caused by the photolysis of molecules by hard solar UV photons and the subsequent chains of chemical reactions, which can delay the re­radiation of the sun­based energy into the night. Airglow is strongly variable on many time scales. We will demonstrate the effect and the variability of the different sky­background components based on data and models related to the Very Large Telescope of the European Southern Observatory at Cerro Paranal in Chile, where light pollution can be neglected. It is the site with the most detailed description of the night­sky radiation, so far. As Cerro Paranal is characterised by a very clear atmosphere, we will also briefly discuss possible changes in the contributions of the different sky­background components depending on the site properties.

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10­ How the Sky Brightness Depends on Wavelength, Aerosol Content, Ground reflectance, Lamps Photometry, Terrain and Obstacles

Martin Aubé,1 1 Cégep de Sherbrooke, Sherbrooke J1E 4K1, Canada

475, rue du Cégep Tel: 819­564­6350 (4146), e­mail: martin.aube@cegepsherbrooke.qc.ca

Abstract Propagation of artificial light at night (ALAN) in the environment is now known to have non negligible consequences on fauna, flora and human health which depend on light levels and their spectral power distributions. But it is also strongly related to the various physical processes involved in the radiative transfer of this light into the atmosphere along with its interactions with the built and natural environment. This paper focus on the behaviour of the indirect light scattered under clear sky conditions. Various interaction processes between anthropogenic light sources and the natural environment are discussed on the basis of a sensitivity analysis conducted with the light pollution radiative transfer model, Illumina. We will discuss the impact of 1­ the molecular and aerosol scattering and absorption, 2­ the second order of scattering, 3­ the topography and obstacle blocking, 4­ the ground reflectance, 5­ the spectrum of light devices and their angular emission functions. This analysis considers different behaviour as a function of the distance from the city centre, along with different zenith viewing angles in the principal plane.

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11­ Quantifying Night­Time Aerosol Optical Depth Using Star­ and Moon­Photometry

Konstantin Baibakov,1 Yann Blanchard,1 Norman T. O’Neill,1 and Alain Royer1 1 CARTEL, Université de Sherbrooke, Sherbrooke, Québec, Canada

e­mail: k.baibakov@usherbrooke.ca

Abstract Quantifying sky brightness and the effects of light pollution usually requires an estimation of atmospheric aerosol loading. Inversely, night­time aerosol optical measurements can be influenced by artificial lights and need to be taken into account. Aerosol optical depth (AOD) is a robust extensive parameter proportional to the total column aerosol concentration. Night­time AOD measurements can be obtained using relatively recent techniques of star­ and moon photometry, but have so far been limited to only a handful of sites around the world. We have been acquiring star photometry measurements since 2007 during various short­term campaigns at several locations in Canada. In addition, in 2013 a sun photometer was installed at a rural mid­latitude site in Sherbrooke, Québec. In this paper, we present several examples of star photometry measurements and discuss how they can be influenced by various problems, including light pollution. Furthermore, results from star photometry­moon photometry intercomparisons are also presented. When possible, we checked night­time AODs for continuity relative to day­time sun photometry values. Lidar backscatter data was also used as a consistency check whenever available.

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12­ In Situ Estimation of Atmospheric Properties for Light Pollution Measurements and Modeling

Zoltán Kolláth,1,2 Anita Dömény,1 and Balázs Nagy1 1 University of West Hungary, Savaria Campus, Károlyi Gáspár tér 4, 9700 Szombathely, Hungary

2 MTA CsFK Konkoly Observatory, Konkoly Thege út 15­17, 1121 Budapest, Hungary, tel: +36 20 9721420, e­mail: kollath.zoltan@ttk.nyme.hu

Abstract

To interpret light pollution measurements and to perform parallel numerical modeling, it is often necessary to estimate atmospheric parameters, like aerosol content and optical depth. Since the atmosphere is a very complex system with different ingredients, temporal and spatial variations, in real situations only averaged and approximate parameters can be used. Therefore, instead of the complex, multivariate system, model atmospheres with only a few parameters are included in radiation transfer models. It is demonstrated, that these simplified atmosphere models can provide satisfactory model results, if the same approximations are used both in the light pollution code and during the in situ determination of atmospheric measurements (i.e. cancellation of errors). When the goal is not to determine the fine tuned model of the atmosphere but to qualify light pollution, such an approximation can be a fruitful tool in light pollution research. We provide tests on different treatments e.g. fitting sky brightness components due to moonlight or laser beams to approximate scattering properties of the atmosphere. We also present a comparison of these estimates to other methods, like extinction measurements based on astronomical photometry, meteorological data and inversion methods.

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13­ Manage Lighting Applications with Three Spectral Indices Johanne Roby,1 Antoine Morin­Paulhus,1 and Martin Aubé1

1 Cégep de Sherbrooke, QC J1E 4K1, CANADA tel: +1 819­564­6350, e­mail: johanne.roby@cegepsherbrooke.qc.ca

Abstract

The impact of artificial light on many biological processes is highly linked to the spectral content of the light. This is because each biological process shows a different sensitivity to the wavelength of light. The parameters that currently exist to characterize lighting such as color temperature (CCT) and color rendering index (CRI) were developed in the 1930s to quantify light for primarily aesthetic consideration. Since then, the understanding of the impact of artificial light on biological processes and on the environment has evolved significantly. We must then consider the spectral characteristics of artificial light along with the total light power. CCT and CRI values give little information about the spectral composition of light and its possible impacts on health and environment. It is therefore necessary to develop new tools that reflect the spectral distribution to characterize the lighting and manage their application. In 2013, Aubé et al. introduced three spectral indices covering the potential impacts of artificial lighting on three biological processes: 1­ melatonin suppression in human, 2­ plant photosynthesis, and 3­ human scotopic vision. Those indices are based on the spectral composition of artificial light and the spectral sensitivity of biological processes. During this talk, we will present how we could help authorities and population to manage the lighting using those three indices. We will also summarize some correlations between CCT, Blue light content and the spectral indices and how we could extend the concept of the indices to other biological processes such as the attractiveness of insects and bats in the light.

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14­ An Online Tool to Get Complete Spectral Information and Potential Impacts for a Large Variety of Commercial Lamps

Antoine Morin­Paulhus1, Johanne Roby1 , Martin Aubé1 1 Cégep de Sherbrooke, QC J1E 4K1, CANADA

tel: +1 819­564­6350, e­mail: antoine.morin.paulhus@gmail.com

Abstract Our research group is working to develop a light spectral database intended to provide basic tools to facilitate studies of artificial light on environmental and health impact. It is made available for to the scientific community as well as the public in general. The database contains the spectral power distribution of a large variety of commercial light bulbs or lamps along with associated correlated color temperature, blue content (from 405 to 530nm) and the three spectral indices developed by Aubé et al. in 2013. We will present an overview of the tool chain that we used to build the online Lamp Spectral Distribution Database (LSPDD). These tools include the steps of spectral normalization, the calculation of potential impact indices and the calculation of other lamp data such as the correlated color temperature (CCT). We will show how to use the database to search lamps, view their spectra along with spectral data and how to compare them with reference spectra such as melanopsin spectral sensitivity. We also would like to invite the scientific community to contribute to the spectral database.

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15­ Diffuse Light on Satellite Imagery and Sky Brightness A. Sánchez de Miguel1,2 and J. Zamorano1 1 Dept. Astrofísica y CC. de la Atmósfera,

Universidad Complutense de Madrid, 28040 Madrid, Spain 2 Cégep de Sherbrooke, Sherbrooke J1E 4K1, Canada

tel: +34 619358685, e­mail: alejasan@ucm.es

Abstract Diffuse light in dark places with low light pollution was present in DMSP/OLS satellite images. Since this low level radiation appeared near brighter areas, its origin could be related to the wings of the PSF. Using the UCM night sky brightness survey around Madrid area, we have found a relationship of the VIIRS/DNB satellite data and the night sky brightness measured in dark areas. This relationship also holds for the radiation obtained from calibrated pictures taken from the ISS. This implies that the diffuse light observed from space is similar to that measured from land and it is not an image artifact. As an example a preliminary map of the night sky brightness of the central region of Spain created from satellite data is presented. This simple procedure is useful to test models and to generate sky brightness maps when satellite data were fully calibrated.

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16­ Retrieval of Urban Emission Function from Sky Glow Data: an Experimental Approach

Héctor Antonio Solano Lamphar1,2, Miroslav Kocifaj3,4, Frantisek Kundracik3 1 Cátedras CONACYT. Instituto de investigaciones Dr. José María Luis Mora. Programa

Interdisciplinario de Estudios Metropolitanos. Plaza Valentín Gómez Farías #12 Col. San Juan Mixcoac México D.F. C.P 03730

2Instituto de Investigaciones Lumínicas, Los Mochis, Sinaloa, México 3 Faculty of Mathematics, Physics, and Informatics, Comenius University, Mlynská dolina, 842 48

Bratislava, Slovakia 4 ICA, Slovak Academy of Sciences, Dúbravská Road 9, 845 03 Bratislava, Slovakia.

tel: +52 01 55 5598 3777 ext. 1763 e­mail: hsolano@institutomora.edu.mx

Abstract The upwardly emitted radiation from artificial light sources is subject to different performance depending on the optical characteristics of the atmosphere. Fluctuations on the night sky radiance are typically due to variability of aerosol particles, which are the greatest modulators of down welling radiation. These atmospheric variations combine with the physical properties of the ground­based light sources appear decisive in forming the artificial night lighting. Specifically, the night sky radiance varies with so­called emission patterns. The emission function is an important feature of the radiation emitted by a light source and plays a key role in the consequent sky glow. The retrieval of such emission function is of great interest for modelling purposes since this data is required as an input to theoretical models. In order to obtain the emission function from experimental data, we require to measure at least the zenith radiance and the horizontal irradiance. This work attempts to present the development of an experimental device that can identify the emission function by field observations. The experiments are based on a recently published work in which the function is theoretically analyzed. A DSLR professional camera with a complete fish eye lens carried out the main measuring process. The field experiments were made at different distances from a city while the taken images were used to retrieve the ratio of zenith radiance relative to horizontal irradiance. The retrieval of the emission function is possible at many places over the world using inexpensive devices and the theoretical model published in MNRAS 439, 3405–3413. The contributions of this paper are of interest to experimentalists concerned in the study of the night sky brightness.

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17­ Angular and Temporal Dependence of Artificial Light at Night Upwelling Towards VIIRS­DNB

Kai Pong Tong,1 Georg Heygster,1 and Justus Notholt1 1 Institut für Umweltphysik, Universität Bremen, Otto­Hahn­Allee 1, 28359 Bremen, Germany

tel: +49 421 218 62186, fax: +49 421 218 45 55, e­mail: rktong@uni­bremen.de

Abstract In order to accurately understand and model skyglow patterns, it is important to know how various factors affect the generation and propagation of artificial light at night. One of these significant but less studied variables is the angular distribution of upwelling artificial light. In this study, the incidence angle dependence of the nighttime moonless radiance data of Leipzig and its surroundings taken by the VIIRS­DNB sensor on board the Suomi NPP satellite is investigated. Several isolated towns and villages near Leipzig are selected for a quantitative analysis of the angular dependence of the upwelling artificial light. We find an overall decrease of the radiance with incidence angle on both sides, left and right, of the satellite ground track. Moreover, the relationship between satellite incidence angle and overflight time over a given point on earth is used to analyze the temporal change of the amount of artificial light. The results of the analysis will be presented and implications for skyglow forward modeling and artificial light determination from VIIRS­DNB data will be discussed.

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18­ Biological Thresholds for Nocturnal Light Compared to LED Characteristics

Robert Dick1 1 The Royal Astronomical Society of Canada, and The Canadian Scotobiology Group, P.O. Box 79,

Rideau Ferry, ON K0G 1W0 Email: rdick@csbg.ca

Abstract

Studies have determined the biological thresholds of wildlife to light. Taking advantage of this information requires the development of practical lighting products that both comply with these limits and cater to the human need for better visibility during late­night activity. The lighting industry has developed guidelines for artificial lighting. However they are based on the photopic response of human vision and are therefore biased towards high levels of illumination. In a perfect world illumination should be kept to a minimum to preserve the natural environment, reduce energy use and resource consumption, and the pollution resulting from its generation. The world is not perfect but we present the characteristics of limiting illumination for human activity at night as an exercise to understand how little illumination we need, as opposed to what we want. We then compare the attributes of LED lighting as a guide to the design of light fixtures for a perfect world.

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19­ Light Sources for Protecting the Night Andreas Hänel1, Harald Bardenhagen2

1 Working Group Dark Sky, Museum am Schölerberg, Klaus­Strick­Weg10, D­49082 Osnabrück, Germany

2 Astronomie­Werkstatt “Sterne ohne Grenzen”, Sülzgürtel 42, D­50937 Köln, Germany e­mail: ahaenel@uos.de

Abstract

We will discuss spectral issues for visual perception of the stellar sky, astronomical photography and the impact on vision of night active animals. Based on this information possible light sources are discussed that will influence the critical spectral bands least. Using narrow­band emission LEDs and filters it becomes possible to select the spectral regions for the light sources that have less disturbing influence on astronomical observations and the different night active creatures. The situation in the optical domain is therefore similar to the protection of frequency bands at the radio wavelength. The spectral distributions of different technical solutions have been measured and some have been installed in practice and the results will be discussed.

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20­ Light Measurement and Modelling Requirements of the Biological Sciences

Kellie L Pendoley, and Benjamin Goodsell 1 Pendoley Environmental Pty Ltd, 12A Pitt Way, Perth Western Australia 6154, Australia

tel: +61 8 93306200, e­mail: kellie.pendoley@penv.com.au

Abstract The impact of light pollution is now recognised across a broad range of disciplines originating with the early calls by astronomers to protect the night skies to biologists, medical researchers, urban planners and, increasingly, by regulators. Within each discipline there is a requirement for detecting, measuring and monitoring light so that the problem light can be identified, quantified and tracked over time and light management/reduction actions implemented and verified. This presentation will focus on the needs and problems associated with measuring light to meet regulatory conditions around environmental protection and wildlife conservation. The aspects of biologically meaningful light monitoring and measurement to be addressed are listed below. 1­ The pros and cons of commercially available equipment for use in the field, addressing ease of use in the field, detection limits, precision at low light levels, portability, ability to isolate specific regions of the visible spectrum etc. 2­ Radiometry vs photometry as it pertains to the visibility of light to animals vs humans. Identify the regions of the spectrum visible to different animals that fall outside of the CIE photometric curve and are consequently not accurately quantified by typical commercial instruments. Is it possible to design filters to capture the spectral emissions visible to different animals? 3­ The requirements for precision, accuracy and a well­defined error range in spectral measurements. Environmental regulators need to set specific limits against which the performance of a polluter can be measured. There must be sufficient confidence in the data that the results can stand up in a court of law. 4­ The interpretation and communication of results clearly and simply and understandable to non­scientists. The understanding of the physics, detection and measurement of light is poorly understood by most people and until this area of science can be clearly and simply interpreted and communicated it will not be considered a standard pollutant in the same way as chemical pollutants in air, water and sediment. 5­ Identification of a standard unit of light measurement. Biologists and environmental practitioners need a standard method for measuring light and standard units for reporting to allow cross study comparisons. 6­ Methods for integrating the spectral sensitivity curves of animals with commercial light spectral power curves and photometric measurements (e.g. Lux). Is it possible to quantify the amount of light that falls outside of the CIE curve? 7­ Modelling requirements for industrial light sources. How do we model the visibility of light to a hatchling sea turtle on a beach 15km from a drilling rig flare at night? How can that model be used to assess the impact of that light on the orientation of the hatchlings?

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21­ Determining the Continuous All­Sky Night Brightness Distributions from Discrete Sets of Localized Measurements

Víctor Tilve,1 Josefina F. Ling,1 and Salvador Bará2 1 Astronomical Observatory "R.M. Aller", Dept. of Applied Mathematics, Universidade de Santiago de

Compostela, 15782 Santiago de Compostela, Galicia, Spain. 2 Optics Area, Dept. of Applied Physics, Universidade de Santiago de Compostela, 15782 Santiago de

Compostela, Galicia, Spain tel: +34 881813525, e­mail: salva.bara@usc.es

Abstract

The all­sky night brightness distributions produced by the atmospheric scattering of light from artificial sources can be described by relatively low­order series of suitable polynomial functions. Brightness maps with high spatial resolution can then be reconstructed if the series coefficients are determined. In this communication we show how to estimate these coefficients from discrete sets of measurements made with low­cost brightness detectors of moderate field­of­view.

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22­ The VIIRS Day/Night Band: Creating the Next Generation of Global Remotely­Sensed Nighttime Lights Products

Kimberly Baugh,1 Christopher Elvidge,2 Mikhail Zhizhin,1 Feng Chi Hsu,1 and Tilottama Ghosh1 1 CIRES, University of Colorado, Boulder, Colorado 80303, USA

2 NOAA National Geophysical Data Center, 325 Broadway, Boulder, Colorado 80305 USA tel: +1 303 497 4452, fax: +1 303 497 6513, e­mail: kim.baugh@noaa.gov

Abstract

The Earth Observation Group (EOG) at the National Oceanic and Atmospheric Administration’s National Geophysical Data Center (NOAA/NGDC) has a long history of producing nighttime lights data products using satellite imagery from the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP­OLS). Data products range from nightly mosaics of the nighttime visible band, average composite products produced for a desired time span (lunar cycle, monthly, quarterly, or annual), out to the EOG’s most often used DMSP­OLS product, the global stable lights composite. The OLS global stable lights products were produced for each year the data was available in a digital form and for each DMSP satellite in a day/night orbit. The current record extends from 1992­2013 and spans six different DMSP satellites. The last DMSP satellite in a day/night orbit is not able to collect enough high quality nighttime data to produce a global stable lights product for 2014. While this is the end of the DMSP­OLS era for nighttime lights, the launch of a new sensor in 2011 brings exciting new prospects and possibilities. The Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB), launched on the Suomi National Polar Partnership (SNPP) platform in November of 2011, draws its heritage from the DMSP­OLS visible band, but was designed decades after the latest OLS. This makes for dramatically improved spatial resolution (45X­88X), dynamic range (256X), and increased sensitivity (100X) of the DNB as compared to the OLS. The DNB also has onboard calibration which allows for conversion to radiance units, a vast improvement from the OLS which had only relative digital numbers (DN) in its data stream. Using the newly available data from the VIIRS­DNB allows EOG to extend the record of nighttime lights products beyond the DMSP era, and the opportunity exists to create vastly improved products due to the increased spatial resolution and dynamic range of the DNB. However, creation of the nighttime lights composite products requires extensive pre­processing of the individual overpasses that go into the composite. Filtering, and sometimes correction, must be done to data degraded by the presence of clouds, heavy aerosols, aurora, stray light, moonlight and snow cover. Sensor artifacts, such as the presence of high radiance noise due to cosmic ray hits, have to be flagged. And finally, lights from ephemeral sources such as fires and lightning need to be identified and background (non­light) values need to be identified and removed. Due to the dramatic improvements in the DNB over the OLS, only a handful of existing algorithms could be reused. The current state of EOG’s active DNB algorithm development will be discussed and an overview of currently available nighttime lights products will be shared. A multi­temporal comparison of DNB composite products will be shown, with a tour highlighting areas with change in measured radiances, as well as unique nighttime lights areas around the globe. Finally a comparison will be made between nighttime lights products generated with the DNB and the heritage OLS sensor.

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23­ Use of the SQM­L for All­Sky Light Pollution Measurement Duriscoe, Dan M.,1 White, Jeremy,2 Moore, Chad A,2 Tekatch, Anthony,3 and Douglas L. Welch3

1 Night Skies Program, U.S. National Park Service, Bishop, CA, U.S.A 2 Night Skies Program, U.S. National Park Service, Fort Collins, CO, U.S.A

2 Unihedron, Grimsby, Ontario, Canada tel: +1 760 872 5044, e­mail: dan_duriscoe@nps.gov

Abstract

We assess the utility of the Unihedron SQM­L photometer in assessing the impact of artificial light in the environment over the entire sky and along the horizon. The use of add­on optics and filters, automated and semi­automated pointing devices, as well as new built­in enhanced features including magnetic compass, clinometer, and a nearly flat off­axis angular response improve its suitability for resolving small scale sources of vertical illuminance. Results from all­sky multi­point measurement campaigns and selective pointing at individual light trespass sources are presented and compared with CCD camera and illuminance meter data. We also review the importance of accurate medium resolution near­horizon measures to the protection of wilderness values and sensitive species such as sea turtles. Data and analysis from Gulf Islands National Seashore and areas in California, U.S.A. are presented.

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24­ Calibrated Measurements of Luminance and Sky Glow with a Digital Camera

Peter D. Hiscocks Syscomp Electronic Design, Toronto M4K1J1, Canada tel: +416­465­3007, e­mail: phiscock@ee.ryerson.ca

Abstract

We show how a digital camera may be calibrated for use as a luminance meter for measurements of sky glow and glare from artificial sources. We include description of an integrating sphere used as a calibration source and open­source software for camera control and image analysis.

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25­ Skyglow Phenomenology: Bridging the Gap Between Experiment and Theory

Christopher C.M. Kyba,1,2 1 Deutsches GeoForschungsZentrum Potsdam, Telegrafenberg, 14473 Potsdam, Germany

2 Leibniz Institute of Freshwater Ecology and Inland Fisheries, Müggelseedam 310, 12587, Berlin, Germany

tel: +49 331 288 28973, e­mail: kyba@gfz­potsdam.de

Abstract Recent years have seen a major increase in the scientific interest in measurement and modeling of artificial skyglow and upwelling city light. While this work has improved our understanding of skyglow, there have been very few studies bringing experiments and models together. Such a study would currently be challenging for many reasons. Most recent skyglow measurements have been performed using Sky Quality Meters (in most, but not all cases, directed at zenith), International Year of Astronomy Lightmeters, all­sky cameras, and visual observation of limiting magnitude. With the exception of naked­eye observations, the spectral weighting of these instruments does not match those of visual and non­visual organs or physiological responses. Most measurements report results obtained on clear nights, but cloudy nights are likely more important for understanding the ecological impacts of skyglow. Most models simulate only clear skies, and provide zenith

radiances that do not match instrumental bands (e.g. Wm­2sr—1 and Vλ). Models generally include street lighting as the only light source; the contribution of other sources of light to skyglow has yet to be quantified by experiment. The results of current measurements and models are therefore not directly comparable, and most published papers are entirely theoretical or entirely experimental. In this talk, I aim to start a conversation that will lead to closer cooperation between experimentalists and theoreticians, improved experimental techniques, and more accurate skyglow models.

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26­ Measuring the Darkness with a Solar Simulator: Indoor Calibration of Sky Brightness Meters

M. Pravettoni,1* D. Strepparava,1 N. Cereghetti,1 S. Klett,2 M. Andretta,3 and M. Steiger3 1 University of Applied Sciences and Arts of Southern Switzerland, CH­6952 Canobbio, Switzerland

2 Dark­Sky Switzerland, Sezione Ticino, CH­6998 Termine, Switzerland 3 Repubblica e Cantone Ticino, Ufficio del Monitoraggio Ambientale, CH­6500 Bellinzona,

Switzerland *Corresponding author: tel: +41 58 666 6250, fax: +41 58 666 6259, mauro.pravettoni@supsi.ch

Abstract

The indoor calibration of sky brightness meters requires, in the most accurate and reproducible way, extremely low values of irradiance which is rather unusual for the photovoltaic (PV) testing laboratory at the University of Applied Sciences and Arts of Southern Switzerland (SUPSI), the Swiss ISO 17025 accredited PV testing centre. Researchers at SUPSI are used to test PV cells or modules on solar simulators, between 100 and 1000 W/m2 total irradiance, roughly spanning the global irradiance at central European and North American latitudes all over the year. In this the collaboration between SUPSI, Dark­Sky Switzerland and the Canton of Ticino, within the framework of OASI (Environmental Observatory of Southern Switzerland, www.ti.ch/oasi), the testing equipment at SUPSI was modified in order to reach a controlled total irradiance of several orders of magnitude below the standard values, down to fractions of nW/cm2. Sixteen sky brightness meters (Sky Quality Meter®, SQM­LE, by Unihedron) from the OASI network (measurement points and observatories), typically installed at different sites and altitudes in Southern Switzerland, were tested in order to assess the impact of the ageing of their protective glasses on the calibration coefficients. A steady­state 1000 W/m2 solar simulator by Oriel­Newport (±2% spatial non­uniformity, ±0.5% temporal instability, Class A spectral irradiance in the 400­900 nm wavelength band) was used to test the devices indoors. The output power was first adjusted to 25 mW/cm2 total irradiance (measured with a calibrated reference PV cell). Then, while keeping the devices at a controlled temperature (25±1°C), a set of calibrated neutral density filters (optical density from 1.0 to 7.5) was introduced, down to the minimum irradiance of 0.79 nW/cm2 (maximum darkness: 19 mag/arcsec2). For each device, the measured brightness was registered as a function of irradiance. The equipment allowed calibrating the devices accurately from 6 to 19 mag/arcsec2, confirming their linear response.

In this paper, the authors present full results of the calibration campaign: brightness calibration, with and without protective glasses; transmittance measurement of the glasses; spectral response of the devices and a detailed uncertainty analysis. The work will serve as a useful tool and best­practice guide to any research centre using similar devices for sky darkness monitoring. Further ongoing activities include the characterization of the devices at different temperatures.

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27­ Light Pollution Studies on Montsec Reserve Using the New Catalan Light Pollution Network

Salvador J. Ribas,1 Ramon Canal­Domingo,1 Sergi Paricio,2 Lluís Gustems 2 and Carmen O. Calvo 2 1 Parc Astronòmic Montsec, COU, Camí del coll d’Ares s/n, E­25691 Àger, Catalunya, Spain. 2 Servei per a la Prevenció de la Contaminació Acústica i Lluminosa, Generalitat de Catalunya,

Av.Diagonal 523­525, E­08029 Barcelona, Catalunya, Spain. tel: +34 973 455 246, e­mail: sjribas@montsec.cat

Abstract

Montsec Mountains are a special protected place in Catalonia (NE of Iberian Peninsula) This area has been selected as the best place to do Astronomy in Catalonia. Since 2013, the site has been declared Starlight Reserve and Touristic Destination. Since 2012, different projects took place in Montsec to evaluate the quality of the night sky and the effects of Light Pollution of nearby (or not so near) municipalities. Extensive measurements have done using SQM (Sky Quality Meter) techniques in RoadRunner configuration (installed on a car) to determine the situation and evolution of the night sky brightness all around the Reserve (1 600 square km). These studies allowed us to detect some excellent areas (better than 21.4 mag. at zenith) in Montsec Reserve. In addition the same technique allowed us to evaluate the effects of cities in the natural protected sky, evaluating the effects of Lleida city (with close to 200 000 inhabitants). Recently a new tool is available for LP studies. This is the Catalan Light Pollution Network created by Parc Astronomic Montsec and Catalan Light Pollution Service to monitor continuously the status of the night sky brightness in some selected positions. The network is based in SQM devices installed some of them in Montsec area and some others in the cities that are affecting the quality of Montsec sky. The SQM data obtained can be combined with other environmental data. For example we can use ceilometer data to evaluate and correlate the clouds and aerosol status in relation with the night sky brightness. Also general meteorological data are available in almost every site with an SQM device.

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28­ Intercomparison Campaigns of Night Sky Brightness Measuring Techniques

Salvador J. Ribas,1 and Christopher C.M. Kyba,2 on behalf of COST­LoNNe Intercomparison Campaigns

1 Campaign coordinator. Parc Astronòmic Montsec, COU, Camí del coll d’Ares s/n, E­25691 Àger, Catalunya, Spain. tel: +34 973 455 246, e­mail: sjribas@montsec.cat

2 LoNNe WG1 leader. Helmholtz­Zentrum Potsdam. Deutsches GeoForschungsZentrum GFZ. Stiftung des öff. Rechts Land Brandenburg. Telegrafenberg, 14473 Potsdam.

Abstract

Loss of the Night Network (LoNNe) is an action of the European Cooperation in Science and Technology (COST) framework program. This action is focused in improving the knowledge of the multiple effects of increasing artificial illumination worldwide. One of the activities of this action is to promote the intercomparison of different techniques used in evaluating the night sky brightness (NSB) with the organization of annual campaigns in different sites in Europe. In these campaigns, researchers working on the topic of measuring NSB take measurements simultaneously at one site with different instruments, including Sky Quality Meters, Lightmeters, all sky devices such as ASTMON or DSLR cameras, and astronomical telescopes. The aim is to understand the gains, offsets, and systematic uncertainties associated with different measurement devices and techniques, and to generate recommendations for researchers from different background in how best to measure NSB. The first campaign was hosted in 2013 by Dark Sky Slovenia on the island of Lastovo in Croatia. This is a very dark and homogeneous area that allowed us to reach the limits of some instruments and evaluate how every instrument works in areas with little or no skyglow. The second campaign was hosted in 2014 by Universidad Complutense de Madrid. Measurements were conducted both in the city of Madrid and in a dark area in the province of Avila in Spain. This campaign allowed us to test the instruments in an extremely light polluted site, to perform measurements taken in movement using devices installed on the top of cars and, finishing with measurements in an area with little skyglow at zenith,but not as homogeneous at the horizon as Lastovo island. Spectral characterization of devices and filters was also performed in an optical laboratory. In 2015, the campaign will take place in March in Florence (Italy), and the final campaign of the LoNNe action will take place in 2016. The results from each of these campaigns will allow us to give the recommendations for the use of the different kinds of instruments to evaluate NSB. In this talk, the campaigns will be described in detail, and preliminary results will be presented.

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29­ Case Studies of Remote Sensing and Field Experiments on the Contribution of Artificial Light Sources to the Night Sky Observed in

Hong Kong Chu Wing SO,1 Chun Shing Jason PUN2

1,2 Department of Physics, The University of Hong Kong, Pokfulam, Hong Kong +852 2859 2360, fax: +852 2559 9152 1 e­mail: socw@connect.hku.hk 2 e­mail: jcspun@hku.hk

Abstract

The extent, distribution, and properties of the light pollution condition in the populous metropolis Hong Kong, China had been examined through a sky brightness monitoring network with 18 light sensors installed around the city from 2010. The ground­based measurements confirmed that the night sky brightness levels in the city depends strongly on the use of outdoor artificial light sources near the observing stations. With a hilly and complex terrain, the population density and hence the light pollution conditions in Hong Kong varies largely with geographical locations. Night­time images of the Earth provide a possible data source for expanding the geographical coverage of light pollution study. A preliminary study on the high resolution (at about 68m/pixel) night­time photography of Hong Kong taken from the Kodak DCS760C Camera onboard the International Space Station (ISS) was conducted. A comparison between the remote sensing data and ground­based measurements reveals a strong correlation among two methods, suggesting a good potential for the application of remote­sensing techniques on studying light pollution.

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30­ Night Time Spectral Behavior of the SQM Henk Spoelstra1

1 Lumineux Consult, Landgraafstraat 96, 6845 ED Arnhem, The Netherlands tel: +31 26 7850904, e­mail: henk@lumineux­consult.com

Abstract

The widely used SQM has a broad spectral response in comparison to the photometrical or Johnson V­band. The spectral response of the SQM is enhanced towards the blue part of the visible spectrum. This influences the measured values by the SQM during edges of the night, during moon lit skies and under cloudy conditions. The extend of this influence is presented and explained based on field data with a SQM, a photometrical device and a filter band color meter.

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31­ Assessment of Light Pollution Impacts from Oil and Gas Developments

Duriscoe, Dan M1., Moore, Chad A2., Wren, Bill3, and Robert Meadows2 1 Night Skies Program, U.S. National Park Service, Bishop, CA, U.S.A

2 Night Skies Program, U.S. National Park Service, Fort Collins, CO, U.S.A 3 University of Texas McDonald Observatory, Fort Davis, TX, U.S.A.

tel: +1 760 872 5044, e­mail: dan_duriscoe@nps.gov

Abstract Temporary and permanent developments in sparsely populated oil and gas producing regions with pristine night skies include significant outdoor lighting, which introduces stray light at night into these and surrounding areas. We examine the observed and potential impacts of sky glow and light trespass in North Dakota, New Mexico, and Texas, using a variety of observational, analytical, and remote sensing tools. The effects of increased sky glow at Theodore Roosevelt National Park, North Dakota are examined with regard to wilderness character. Potential light trespass and glare from exploratory drilling near Chaco Culture National Historic Site, New Mexico, is discussed, along with strategies for mitigation. Expanded development of the Permian Basin oil field presents challenges for control of temporary lighting in counties of west Texas with existing laws controlling outdoor lighting.

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32­ The Galician Night Sky Brightness Monitoring Network Salvador Bará,1 Víctor Tilve,2 Santiago Salsón,3 Miguel Rúa,3 and Vicente Pérez­Muñuzuri3

1 Optics Area, Dept. of Applied Physics, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain

2 Astronomical Observatory "R.M. Aller", Dept. of Applied Mathematics, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain.

3 MeteoGalicia, Consellería de Medio Ambiente, Territorio e Infraestruturas, Rúa Roma nº 6, 15707 Santiago de Compostela, Galicia, Spain.

tel: +34 881813525, e­mail: salva.bara@usc.es

Abstract The Galician Night Sky Brightness Monitoring Network is a public system of SQM­LR detectors installed in several weather stations of MeteoGalicia, the Galician official meteorological agency, in cooperation with the University of Santiago de Compostela. A set of 14 detectors continuously acquire brightness data at sites located within heavily light polluted urban areas as well as in remote places at the Eastern Mountains and National Parks of Galicia. Ten­minute resolution data are available in real time for public dissemination and download from the MeteoGalicia website. One­minute resolution datasets are freely available upon request. In this communication we describe this network and the science results obtained after its first operational year.

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33­ A Moon Spectrometer to Infer the Aerosol Optical Depth and Sky Brightness During the Night

William Blanchette,1 Sami Chibani,1 and Martin Aubé1 1 Cégep de Sherbrooke, Sherbrooke J1E 4K1, Canada

e­mail: blanchettew@gmail.com

Abstract Measuring the Aerosol Optical Depth (AOD) is of particular importance in the monitoring of the aerosol contributions to the global radiative forcing. Most measuring methods are based on direct or indirect observation of sunlight and thus are only available for use during daylight hours. Attempts have been made to measure AOD behavior at night with star photometry, and more recently with moon photometry. We are presenting the design of an automated spectrometer to monitor AOD by observing the moon spectrum. This Spectrometer for Aerosol Night Detection (SAND) is the fifth generation of its kind. The SAND platform was introduced in 2005 to evaluate the sky brightness levels in the Mont­Mégantic international dark­sky reserve. A spectrum represents a clear advantage in comparison to filter wheel radiometry, as it render it possible to distinguish the other sources of night sky illumination surrounding the moon disk. These sources are: 1­ the light pollution; 2­ the light scattered from the moon; 3­ the star light background; 4­ the northern lights. With a detailed spectral information, we extract the contribution of each source while determining the light from the moon disk without any contamination. As a side effect, our instrument will be able to monitor the spatio­temporal evolution of the sky brightness induced by light pollution. In this paper we present the evolution of that project along with the very first results.

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34­ A Satellite Based Intrusive Light Model Simon Houle,1 Daphnée Couture,1 Gabrielle Déry­Rouleau,1 Gabriella Gagné,1 Gaspard Reulet,1 and

Martin Aubé1 1 Cégep de Sherbrooke, Sherbrooke J1E 4K1, Canada

e­mail: simonhoule.0@gmail.com

Abstract We produced a model of intrusive light for Sherbrooke with a set of satellite images. We used VIIRS­DNB in combination with MODIS reflectance imagery and with an averaged characterization of light fixtures for different city areas. The photometric properties of light fixtures were estimated by random sampling of a few streets per area with the help of Google Streetview. Actually, it is possible to recognize the light fixtures models with Google Streetview and to count them to establish the relevant mix of their photometry functions for each area. We are determining the amount of light emitted in 3 main directions: 1­the upward light reaching the VIIRS sensor; 2­ the downward light reflected by the ground; 3­the light reaching a typical bedroom windows (with a coarse estimate of distance and height of windows relative to the lamp). This vector layer was converted to raster format to produce an estimated map of the intrusive light that enters a typical bedroom window. The spatial resolution of the map is 750m x 750m. The calculation of the intrusive light map is made with the raster calculator capabilities of QGIS software. To evaluate the accuracy the intrusive light map, we acquired illumination data in a number of bedrooms in different part of the city. The comparison between the modeled map and the in­situ measurements is presented in this paper.

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35­ Comparing the Night Skies Over Stockholm/Sweden and Vienna/Austria

Johannes Puschnig,1 Thomas Posch,2 Magnus Näslund,1 and Stefan Uttenthaler2 1 Department of Astronomy, Oskar Klein Centre, Stockholm University, AlbaNova University Centre,

SE­106 91 Stockholm, Sweden 2 Institut für Astrophysik, Türkenschanzstraße 17, A­1180 Wien, Austria

tel: +46 8­5537 8542 , fax: +46 8­5537 8510, e­mail: johannes.puschnig@astro.su.se

Abstract We are monitoring the zenithal night sky brightness (NSB) in Stockholm/Sweden and Vienna/Austria using Sky Quality Meters (SQMs). From this data we derive the level of light pollution depending on time and environmental conditions. We discuss the differences between both cities in terms of lighting strategies and their implications on light pollution. Our comparison is based on winter and spring data only, when nautical twilight corresponding to a sun elevation of ­12 degree is still reached in Stockholm. Such a comparison is of particular interest because both cities have comparable numbers of inhabitants but diverse lighting policies. Within the so called "larger urban zone" (LUZ) as defined by Eurostat, a population of 1.9 and 2.2 million is found for Stockholm and Vienna, respectively. However, the population densities differ, with a 67 percent larger density in Vienna. Nevertheless, our analysis suggests that the level of light pollution is substantially larger in Stockholm. Additionally, using spectroscopic data we compare the spectra of the night sky in Vienna and Stockholm, and we furthermore discuss differences between the SQM based magnitudes and the commonly used Johnson V­band magnitudes.

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36­ Characterizing Night Sky Brightness In and Around Tucson and Nearby Observatory Mountaintops

Constance E. Walker1, Linsey Jensen2, Rachel Nydegger3 and Zachery Watson4 1 National Optical Astronomy Observatory, 950 N Cherry Ave, Tucson, AZ 85719 USA

2 Purdue University, USA 3 Utah State University, USA 4 University of Arizona, USA

tel: +1 520­318­8535, fax: +1 520­318­8451, e­mail: cwalker@noao.edu

Abstract To characterize the night sky brightness in and around Tucson, Arizona, USA, measurements have been taken since mid­2012 with Unihedron’s Sky Quality Meters (SQM­LU­DL+H devices) stationed in 8 locations: at the National Optical Astronomy Observatory (NOAO) near the center of Tucson, 13 to 14.5 km N, E, S and W of NOAO and on 3 nearby observatory mountaintops. For the first year of data, significant differences between city and mountaintop locations could be seen after data reduction (as much as 3.5 mag/sq arcsec). Brighter locations appeared to darken as the night progressed (as much as 1 mag/sq arcsec). Seasonal variations were seen at most locations, more pronounced for brighter areas (as much as 2 mag/sq arcsec). Trends will be reported on the more recent data.

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37­ Sky Quality Camera as a Quick and Reliable Tool for Light Pollution Monitoring Andrej Mohar1,2

1 Dark­Sky Slovenia, Teslova 30, SI­1000 Ljubljana, Slovenia 2 Euromix Ltd., Teslova 30, SI­1000 Ljubljana, Slovenia

tel: +386 41 738 411, fax: +386 1 426 45 86, e­mail: andrej.mohar@euromix­lj.si

Abstract Light pollution measurements are in theory very simple, but if we want make reliable and accurate measurements of relatively dark or almost pristine sky we got many obstacles. Just a very few astronomy sites provide stable transparency of the atmosphere. Most locations have high variability of aerosols, high altitude almost transparent clouds are often present on the sky. Additional problem is Milky Way because it is necessary to distinguished what is natural (star background) and artificial light. We will present technical possibilities of Sky Quality Camera and recommendations of standard procedures which can provide reliable and worldwide comparable measurements. Because of Milky Way, star background brightness at zenith is changing at any time and this is why we would need additional indexes which can describe quality of the night sky. Lighting industry is in transition from yellow in more blue rich light sources. Sky Quality Camera can detect even small changes of Correlated Color Temperature (CCT) of night sky.

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38­ Implementing Clouds Into the Night Sky Radiance Model Illumina Malcolm St­John,1 and Martin Aubé1

1 Cégep de Sherbrooke, Sherbrooke J1E 4K1, Canada e­mail: malcolm19@hotmail.com

Abstract

In this paper we describe the implementation of a simple cloud scheme into the night sky artificial radiance model Illumina (Aubé 2005) to simulate overcast conditions with a variety of cloud types and base height. We are showing the first results obtained with this new scheme in comparison with the clear sky case presented in Aubé 2014.

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39­ Intercomparing Methods of Night Sky Brightness Measurements Constance E. Walker1 , John Kanemoto2, Amy Juan3 and John Barentine4

1 National Optical Astronomy Observatory, 950 N Cherry Ave, Tucson, AZ 85719 USA 2 STEM Teacher and Research Program, USA 3 Center for Integrated Access Networks, USA

4 International Dark­Sky Association tel: +1 520­318­8535, fax: +1 520­318­8451, e­mail: cwalker@noao.edu

Abstract

The focus of the research was to find out how well different types of instruments that measure night sky brightness inter­compare. The different instruments used in the study were: a digital single­lens reflex (DSLR) camera, three handheld Sky Quality Meters (SQM model L or SQM­L), SQM­UL­DL+H stations, a Night Sky Brightness Monitor (NSBM), the “Loss of the Night” (LON) application for Android phones, the “Dark Sky Meter” (DSM) application for iPhones, and the Globe at Night web application that records the “Naked Eye Limiting Magnitude” (NELM). Sixteen locations were identified throughout the city of Tucson and surrounding areas for taking measurements. The locations had a complete range of sky brightness conditions and included parks, highly populated areas, and observatory mountaintops. As expected, the three SQM­L and the SQM­UL­DL+H data compared well with one another to the 99 percentile using the R2 coefficient. The NSBM on Mt. Hopkins also compared well (91%) with the SQM­L data. The DSM app gave a 93% correlation to SQM­L data. The DSLR camera data provided an 80% correlation to the same data set. The Globe at Night NELM method had a 75% correlation with the SQM­L data. And the LON app data had a 43% correlation. Results will be reviewed.