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Recent works have made strong efforts to produce standardised photometry in RGB bands. For this purpose, we carefully defined the transmissivity curves of RGB bands and defined a set of standard sources using the photometric information present in Gaia EDR3. This work aims not only to significantly increase the number and accuracy of RGB standards but also to provide, for the first time, reliable uncertainty estimates using the BP and RP spectrophotometry published in Gaia DR3 instead of their integrated photometry to predict RGB photometry. Furthermore, this method allows including calibrated sources regardless of how they are affected by extinction, which was a major shortcoming of previous work. The RGB photometry is synthesised from the Gaia BP and RP low-resolution spectra by directly using their set of coefficients multiplied with some basis functions provided in the Gaia catalogue for all sources published in Gaia DR3. The output synthetic magnitudes are compared with the previous catalogue of RGB standards available., Ministerio de Ciencia e Innovación (España), Union Europea, Institute of Cosmos Sciences University of Barcelona (ICCUB, Unidad de Excelencia 'Maria de Maeztu'), Marie Curie Actions, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2014 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/4.0/). This paper was conceived of and planned during activities of the EU COST Action ES1204 (Loss of the Night Network). The researchers were supported by grants from the German Federal Ministry of Education and Research (BMBF-033L038A), the Berlin Senate Department for Economics, Technology and Research (Lichtimmissionen im offentlichen Raum) and an FPU grant (FormaciÓn de Profesorado Universitario) from the Spanish Ministry of Science and Innovation (MCINN) to Alejandro Sánchez de Miguel. The support of AYA2012-31277 and AYA2013-46724-P and the Spanish Network for Light Pollution Studies (AYA2011-15808 E) is also acknowledged., Images of the Earth at night are an exceptional source of human geographical data, because artificial light highlights human activity in a way that daytime scenes do not. The quality of such imagery dramatically improved in 2012 with two new spaceborne detectors. The higher resolution and precision of the data considerably expands the scope of possible applications. In this paper, we introduce the two new data sources and discuss their potential limitations using three case studies. Data from the Visible Infrared Imaging Radiometer Suite Day-Night Band (VIIRS DNB) is shown to have sufficient resolution to identify major sources of waste light, such as airports, and we find considerable variation in the peak radiance of the world's largest airports. Nighttime imagery brings "cultural footprints" to light: DNB data reveals that American cities emit many times more light per capita than German cities and that cities in the former East of Germany emit more light per capita than those in the former West. Photographs from the International Space Station, the second new source of imagery, provide some limited spectral information, as well as street-level resolution. These images may be of greater use for epidemiological studies than the lower resolution DNB data., German Federal Ministry of Education and Research, Berlin Senate Department for Economics, Technology and Research (Lichtimmissionen im offentlichen Raum), FPU grant (Formación de Profesorado Universitario) from the Spanish Ministry of Science and Innovation (MCINN), Spanish Network for Light Pollution Studies, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. © 2014 The Autors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Meteor stations deployed at Sevilla, La Hita, Huelva, El Arenosillo, Sierra Nevada and La Pedriza have been funded by the first author. We acknowledge partial support from the Spanish Ministry of Science and Innovation (projects AYA2011-26522, AYA2012-31277 and AYA2012-30717). We thank the AstroHita Foundation for its continuous support in the operation of the meteor observing station located at La Hita Astronomical Observatory., We have analysed the meteor activity associated with meteoroids of fresh dust trails of Comet 209P/LINEAR, which produced an outburst of the Camelopardalid meteor shower (IAU code #451, CAM) in 2014 May. With this aim, we have employed an array of high-sensitivity CCD video devices and spectrographs deployed at 10 meteor observing stations in Spain in the framework of the Spanish Meteor Network. Additional meteoroid flux data were obtained by means of two forward-scatter radio systems. The observed peak zenithal hourly rate was much lower than expected, of around 20 meteors h(-1). Despite of the small meteor flux in the optical range, we have obtained precise atmospheric trajectory, radiant and orbital information for 11 meteor and fireball events associated with this stream. The ablation behaviour and low tensile strength calculated for these particles reveal that Camelopardalid meteoroids are very fragile, mostly pristine aggregates with strength similar to that of the Orionids and the Leonids. The mineral grains seem to be glued together by a volatile phase. We also present and discuss two unique emission spectra produced by two Camelopardalid bright meteors. These suggest a non-chondritic nature for these particles, which exhibit Fe depletion in their composition., Spanish Ministry of Science and Innovation, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

NIXNOX es un proyecto propuesto y apoyado por la Sociedad Española de Astronomía (SEA) con el fin de localizar lugares en España donde se pueda disfrutar del cielo nocturno oscuro y estrellado. Se pretende crear una plataforma que anime a la sociedad a contemplar el cielo nocturno y a las administraciones locales a cuidarlo. La recopilación de los datos de brillo de fondo de cielo y otra información relevante se está realizando con la colaboración de las asociaciones de astrónomos aficionados., Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, FALSE, pub

© Pergamon-Elsevier Science Ltd. This research was supported by an FPU grant (Formación de Profesorado Universitario) from the Spanish Ministry of Science and Innovation (MCINN) to Alejandro Sánchez de Miguel. This work has been partially funded by the Spanish MICINN (AYA2009-10368, AYA2012-30717, AYA2012-31277), by the Spanish program of International Campus of Excellence Moncloa (CEI) and by the Madrid Regional Government through the AstroMadrid Project (CAM S2009/ESP-1496, http://www.laeff.cabinta-csic.es/ projects/astromadrid/main/index.php). The support of the Spanish Network for Light Pollution Studies (Ministerio de Economía y Competitividad, Acción Complementaria AYA2011-15808-E) is acknowledged. Thanks goes also to Francisco Ocaña and Jessica Starkey for the critical review of this text., We present the results of the analysis of satellite imagery to study light pollution in Spain. Both calibrated and non-calibrated DMSP-OLS images were used. We describe the method to scale the non-calibrated DMSP-OLS images which allows us to use differential photometry techniques in order to study the evolution of the light pollution. Population data and DMSP-OLS satellite calibrated images for the year 2006 were compared to test the reliability of official statistics in public lighting consumption. We found a relationship between the population and the energy consumption which is valid for several regions. Finally the true evolution of the electricity consumption for street lighting in Spain from 1992 to 2010 was derived; it has been doubled in the last 18 years in most of the provinces. (C) 2013 Elsevier Ltd. All rights reserved, Ministerio de Ciencia e Innovacion (MICINN), Comunidad de Madrid, Campus de Excelencia Internacional (CEI) Moncloa, España, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© The Chartered Institution of Building Services Engineers. This work has been partially funded by the Spanish MICINN [AYA2012-30717, AYA2012-31277 and AY2013-46724-P], by the Spanish program of International Campus of Excellence Moncloa (CEI), the Madrid Regional Government through the SpaceTec Project [S2013/ICE-2822], the Galician Government [Programa de Consolidación e Estructuración de Unidades de Investigación Competitivas, grant CN 2012/156], by a FPU grant (Formación de Profesorado Universitario) from the Spanish Ministry of Science and Innovation (MCINN) to Alejandro Sánchez de Miguel. The support of the Spanish Network for Light Pollution Studies (Ministerio de Economía y Competitividad, Acción Complementaria AYA2011-15808-E) and the municipality of Deltebre is also acknowledged., In this work, we propose an approach to estimating the amount of light wasted by being sent towards the upper hemisphere from urban areas. This is a source of light pollution. The approach is based on a predictive model that provides the fraction of light directed skywards in terms of a small set of identified explanatory variables that characterise the urban landscape and its light sources. The model, built via the statistical analysis of a wide sample of basic urban scenarios to compute accurately the amount of light wasted at each of them, establishes an optimal linear regression function that relates the fraction of wasted flux to relevant variables like the kind of luminaires, the street fill factor, the street width, the building and luminaire heights and the walls and pavement reflectances. We applied this model to evaluate the changes in emissions produced at two urban nuclei in the Deltebre municipality of Catalonia. The results agree reasonably well with those deduced from the radiance measurements made with the VIIRS instrument onboard the Suomi-NPP Earth orbiting satellite., Ministerio de Ciencia e Innovación (MICINN), Ministerio de Economía y Competitividad (MINECO), Comunidad de Madrid, Programa Campus de Excelencia Internacional Moncloa (CEI), Comunidad Autónoma de Galicia - Programa de Consolidación e Estruturación de Unidades de Investigación Competitivas, Formación de Profesorado Universitario (FPU), Spanish Network for Light Pollution Studies - Ministerio de Economía y Competitividad (MINECO), España, Ayuntamiento de Deltebre, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2015 Optical Society of America. This work was partially funded by the Xunta de Galicia, Programa de Consolidación e Estruturación de Unidades de Investigación Competitivas, grant CN 2012/156, the Spanish Ministry of Science and Innovation MICINN (AYA2012-30717, AYA2012-31277, AYA2013-46724-P, and FPA2010-22056-C06- 06), the Spanish program of International Campus of Excellence Moncloa (CEI) and the Madrid Regional Government through the SpaceTec Project (S2013/ICE-2822). A. Sánchez de Miguel was supported by an FPU grant from MICINN. This work was developed within the framework of the Spanish Network for Light Pollution Studies (Ministerio de Economía y Competitividad, Acción Complementaria AYA2011-15808-E). Useful comments from two anonymous reviewers are also acknowledged., The Zernike power spectra of the all-sky night brightness distributions of clear and cloudy nights are computed using a modal projection approach. The results obtained in the B, V, and R Johnson-Cousins' photometric bands during a one-year campaign of observations at a light-polluted urban site show that these spectra can be described by simple power laws with exponents close to -3 for clear nights and -2 for cloudy ones. The second-moment matrices of the Zernike coefficients show relevant correlations between modes. The multiplicative role of the cloud cover, that contributes to a significant increase of the brightness of the urban night sky in comparison with the values obtained on clear nights, is described in the Zernike space., Xunta de Galicia, Ministerio de Ciencia e Innovacion (MICINN), España, Campus de Excelencia Internacional (CEI) Moncloa, España, Comunidad de Madrid, Ministerio de Ciencia e Innovacion (MICINN), España, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2022 by the authors. Funding: This work is part of the R&D project CEX2019-000910-S, funded by MCIN/AEI/10.13039/501100011033/, from Fundació Cellex, Fundació Mir-Puig, and from Generalitat de Catalunya through the CERCA program. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 847635 (UNA4CAREER). RALAN map project. This work was supported by the EMISSI@N project (NERC grant NE/P01156X/1). G.M-G. acknowledges support from the Austrian Science Fund (FWF) through SFB BeyondC F7102 and from Fundació LaCaixa. A.D. acknowledges NOQIA; Ministerio de Ciencia y Innovation Agencia Estatal de Investigaciones (PGC2018-097027-BI00/10.13039/501100011033, CEX2019-000910- /10.13039/501100011033, Plan National FIDEUA PID2019-106901GB-I00, FPI, QUANTERA MAQS PCI2019-111828-2, QUANTERA DYNAMITE PCI2022-132919, Proyectos de I+D+I “Retos Colaboración” QUSPIN RTC2019-007196-7); European Union NextGenerationEU (PRTR); Fundació Cellex; Fundació Mir-Puig; Generalitat de Catalunya (European Social Fund FEDER and CERCA program (AGAUR Grant No. 2017 SGR 134, QuantumCAT U16-011424, co-funded by ERDF Operational Program of Catalonia 2014-2020); Barcelona Supercomputing Center MareNostrum (FI-2022-1-0042); EU Horizon 2020 FET-OPEN OPTOlogic (Grant No 899794); National Science Centre, Poland (Symfonia Grant No. 2016/20/W/ST4/00314); European Union’s Horizon 2020 research and innovation programme under the Marie-Skłodowska-Curie grant agreement No 101029393 (STREDCH) and No 847648(“La Caixa” Junior Leaders fellowships ID100010434: LCF/BQ/PI19/11690013, LCF/BQ/PI20/11760031, LCF/BQ/PR20/11770012,LCF/BQ/PR21/11840013). A.D. further acknowledges the financial support from a fellowship granted by la Caixa Foundation (ID 100010434, fellowship code LCF/BQ/PR20/11770012). Project cofinanced by the Diputació de Barcelona through the BiblioLab program (21296). Acknowledgments: Thanks to the “Cit, The analysis of the colour of artificial lights at night has an impact on diverse fields, but current data sources have either limited resolution or scarce availability of images for a specific region. In this work, we propose crowdsourced photos of streetlights as an alternative data source: for this, we designed NightUp Castelldefels, a pilot for a citizen science experiment aimed at collecting data about the colour of streetlights. In particular, we extract the colour from the collected images and compare it to an official database, showing that it is possible to classify streetlights according to their colour from photos taken by untrained citizens with their own smartphones. We also compare our findings to the results obtained from one of the current sources for this kind of study. The comparison highlights how the two approaches give complementary information about artificial lights at night in the area. This work opens a new avenue in the study of the colour of artificial lights at night with the possibility of accurate, massive and cheap data collection., MCIN/AEI, Foundation CELLEX, Fundacio Mir-Puig, Generalitat de Catalunya through the CERCA program, European Commission, European Commission Joint Research Centre, UK Research & Innovation (UKRI), Natural Environment Research Council (NERC), Austrian Science Fund (FWF), Ministerio de Ciencia y Innovation. Agencia Estatal de Investigaciones, Barcelona Supercomputing Center MareNostrum, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Data Availability Statement: All raw data used (DMSP-OLS and VIIRS) are already in the public domain on several platforms like for example Google Earth Engine (https://earthengine.google. com/). The data presented in this research are openly available in https://doi.org/10.5281/zenodo. 5205656. Acknowledgments: We are grateful to C.C.M. Kyba for discussion about calibration, and F. Falchi for assistance with key data on the energy consumption of street lighting in Italy., The global spread of artificial light is eroding the natural night-time environment. The estimation of the pattern and rate of growth of light pollution on multi-decadal scales has nonetheless proven challenging. Here we show that the power of global satellite observable light emissions increased from 1992 to 2017 by at least 49%. We estimate the hidden impact of the transition to solid-state light-emitting diode (LED) technology, which increases emissions at visible wavelengths undetectable to existing satellite sensors, suggesting that the true increase in radiance in the visible spectrum may be as high as globally 270% and 400% on specific regions. These dynamics vary by region, but there is limited evidence that advances in lighting technology have led to decreased emissions., UK Research & Innovation (UKRI), Natural Environment Research Council (NERC), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2021 by the authors. This research was supported by the Council for Higher Education of Israel and by the Cities at Night Project., Artificial night-time light (NTL), emitted by various on-ground human activities, has become intensive in many regions worldwide. Its adverse effects on human and ecosystem health crucially depend on the light spectrum, making the remote discrimination between different lamp types a highly important task. However, such studies remain extremely limited, and none of them exploit freely available satellite imagery. In the present analysis, the possibility to remotely assess the relative contribution of different lamp types into outdoor lighting is tested. For this sake, we match two data sources: (i) the radiometrically calibrated RGB image provided by the ISS (coarse spectral resolution data), and (ii) a set of in situ measurements with detailed spectral signatures conducted by ourselves (fine spectral resolution data). First, we analyze the fine spectral resolution data: using spectral signatures of standard lamp types from the LICA UCM library as endmembers, we perform an unmixing analysis upon NTL in situ measurements; by this, we obtain the estimates for relative contributions of the standard lamp types in each examined in situ measurement. Afterward, we focus on the coarse spectral resolution data: by using various types of statistical models, we predict the estimated relative contributions of each lamp type via RGB characteristics of spatially corresponding pixels of the ISS image. The built models predict sufficiently well (with R-2 reaching similar to 0.87) the contributions of two standard lamp types: high-pressure sodium (HPS) and metal-halide (MH) lamps, the most widespread lamp types in the study area (Haifa, Israel). The restored map for HPS allocation demonstrates high concordance with the network of municipal roads, while that for MH shows notable coincidence with the industrial facilities and the airport., Council for Higher Education of Israel, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2021 The Authors. The authors are grateful for the exceptionally careful reading by the referee, whose constructive remarks have helped to improve the paper, making the text more precise and readable. The authors acknowledge financial support from the Spanish Programa Estatal de I+D+i Orientada a los Retos de la Sociedad under grant RTI2018-096188- B-I00, which is partly funded by the European Regional Development Fund (ERDF), S2018/NMT-4291 (TEC2SPACE-CM), and ACTION, a project funded by the European Union H2020-SwafS2018-1-824603. SB acknowledges Xunta de Galicia for financial support under grant ED431B 2020/29. The participation of ASdM was (partially) supported by the EMISSI@N project (NERC grant NE/P01156X/1). This work has been possible thanks to the extensive use of IPython and Jupyter notebooks (Pérez & Granger 2007). This research made use of Astropy,15 a community-developed core Python package for Astronomy (Astropy Collaboration et al. 2013, 2018), Numpy (Harris et al. 2020), Scipy (Virtanen et al. 2020), and Matplotlib (Hunter 2007). This research has made use of the Simbad database and the VizieR catalogue access tool, CDS, Strasbourg, France (DOI: 10.26093/cds/vizier). The original description of the VizieR service was published in A&AS 143, 23., Although the use of RGB photometry has exploded in the last decades due to the advent of high-quality and inexpensive digital cameras equipped with Bayer-like color filter systems, there is surprisingly no catalogue of bright stars that can be used for calibration purposes. Since due to their excessive brightness, accurate enough spectrophotometric measurements of bright stars typically cannot be performed with modern large telescopes, we have employed historical 13-color medium-narrow-band photometric data, gathered with quite reliable photomultipliers, to fit the spectrum of 1346 bright stars using stellar atmosphere models. This not only constitutes a useful compilation of bright spectrophotometric standards well spread in the celestial sphere, the UCM library of spectrophotometric spectra, but allows the generation of a catalogue of reference RGB magnitudes, with typical random uncertainties ∼ 0.01 mag. For that purpose, we have defined a new set of spectral sensitivity curves, computed as the median of 28 sets of empirical sensitivity curves from the literature, that can be used to establish a standard RGB photometric system. Conversions between RGB magnitudes computed with any of these sets of empirical RGB curves and those determined with the new standard photometric system are provided. Even though particular RGB measurements from single cameras are not expected to provide extremely accurate photometric data, the repeatability and multiplicity of observations will allow access to a large amount of exploitable data in many astronomical fields, such as the detailed monitoring of light pollution and its impact on the night sky brightness, or the study of meteors, solar system bodies, variable stars, and transient objects. In addition, the RGB magnitudes presented here make the sky an accessible and free laboratory for the calibration of the cameras themselves., Unión Europea. Horizonte 2020, Ministerio de Ciencia e Innovación (MICINN)/FEDER, Comunidad de Madrid, Xunta de Galicia, EMISSI@N project (NERC), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2021 by the authors. The original manuscript was improved with the comments and suggestions received from four referees We thank The Cities at Night project for its supports. This research was funded by Secretaría Nacional de Ciencias y Tecnología de Panamá and Instituto para la Formación y Aprovechamiento de Recursos Humanos (270-2018-642); ASTRID (P-ESP-000361-0505); TEC2SPACE (S2018/NMT-4291), Programa Estatal Español de I+D+i Orientada a los Retos de la Sociedad (RTI2018-096188-B-I00); STARS4ALL (H2020-ICT-2015-688135); ACTION (H2020-SwafS-2018-1-824603); and EMISSI@N (NE/P01156x/1)., Major schemes to replace other streetlight technologies with Light-Emitting Diode (LED) lamps are being undertaken across much of the world. This is predicted to have important consequences for nighttime sky brightness and color. Here, we report the results of a long-term study of these characteristics focused on the skies above Madrid. The sky brightness and color monitoring station at Universidad Complutense de Madrid (inside the city) collected Johnson B, V, and R sky brightness data, Sky Quality Meter (SQM), and Telescope Encoder Sky Sensor-WiFi (TESS-W) broadband photometry throughout the night, every night between 2010–2020. Our analysis includes a data filtering process that can be used with other similar sky brightness monitoring data. Major changes in sky brightness and color took place during 2015–2016, when a sizable fraction of the streetlamps in Madrid changed from High-Pressure Sodium (HPS) to LEDs. The sky brightness detected in the Johnson B band darkened by 14% from 2011 to 2015 and brightened by 32% from 2015 to 2019., Union Europea. Horizonte 2020, Ministerio de Ciencia e Innovación (MICINN), Secretaría Nacional de Ciencias y Tecnología de Panamá, Comunidad de Madrid, EMISSI@N, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2020 by the authors. Funding from Spanish project AYA2017-89637-R, and from FEDER, is acknowledged. We also acknowledge financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709). This work was supported by the EMISSI@N project (NERC grant NE/P01156X/1)., 'Lockdown' periods in response to COVID-19 have provided a unique opportunity to study the impacts of economic activity on environmental pollution (e.g., NO2, aerosols, noise, light). The effects on NO2 and aerosols have been very noticeable and readily demonstrated, but that on light pollution has proven challenging to determine. The main reason for this difficulty is that the primary source of nighttime satellite imagery of the earth is the SNPP-VIIRS/DNB instrument, which acquires data late at night after most human nocturnal activity has already occurred and much associated lighting has been turned off. Here, to analyze the effect of lockdown on urban light emissions, we use ground and satellite data for Granada, Spain, during the COVID-19 induced confinement of the city's population from 14 March until 31 May 2020. We find a clear decrease in light pollution due both to a decrease in light emissions from the city and to a decrease in anthropogenic aerosol content in the atmosphere which resulted in less light being scattered. A clear correlation between the abundance of PM10 particles and sky brightness is observed, such that the more polluted the atmosphere the brighter the urban night sky. An empirical expression is determined that relates PM10 particle abundance and sky brightness at three different wavelength bands., Gobierno de España, Comisión Europea (FEDER), Ministerio de Ciencia e Innovación, Instituto de Astrofisica de Andalucia, EMISSI@N project (NERC), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© The Authors. This work was supported by the EMISSI@N project (NERC grant NE/P01156X/1), COST (European Cooperation in Science and Technology) Action ES1204 LoNNe (Loss of the Night Network), the ORISON project (H2020-INFRASUPP-2015-2), the Cities at Night project, the European Union’s Horizon 2020 research and innovation programme under grant agreement no 689443 via project GEOEssential, FPU grant from the Ministerio de Ciencia y Tecnologia and F. Sánchez de Miguel. We acknowledge the support of the Spanish Network for Light Pollution Studies (MINECO AYA2011-15808-E) and also from STARS4ALL, a project funded by the European Union H2020-ICT-2015-688135. This work has been partially funded by the Spanish MICINN (AYA2016-75808-R), and by the Madrid Regional Government through the TEC2SPACE-CM Project (P2018/NMT-4291). The ISS images are courtesy of the Earth Science and Remote Sensing Unit, NASA Johnson Space Center. CCMK acknowledges the funding received through the European Union’s Horizon 2020 research and innovation programme ERA-PLANET, grant agreement no. 689443, via the GEOEssential project, and funding from the Helmholtz Association Initiative and Networking Fund under grant ERC-RA-0031. We thank J. Coesfeld for producing Fig. 1. We thank the organizers of the LPTMM 2013 conference for providing a stimulating forum in which we discussed the nature of the diffuse light around cities in detail. Thanks to Emma R. Howard for her help in the editing of this article., Difuse glow has been observed around brightly lit cities in nighttime satellite imagery since at least the frst publication of large scale maps in the late 1990s. In the literature, this has often been assumed to be an error related to the sensor, and referred to as “blooming”, presumably in relation to the efect that can occur when using a CCD to photograph a bright light source. Here we show that the efect seen on the DMSP/OLS, SNPP/VIIRS-DNB and ISS is not only instrumental, but in fact represents a real detection of light scattered by the atmosphere. Data from the Universidad Complutense Madrid sky brightness survey are compared to nighttime imagery from multiple sensors with difering spatial resolutions, and found to be strongly correlated. These results suggest that it should be possible for a future space-based imaging radiometer to monitor changes in the difuse artifcial skyglow of cities., Unión Europea. Horizonte 2020, Ministerio de Economía y Competitividad (MINECO), Ministerio de Ciencia e Innovación (MICCIN), Comunidad de Madrid, EMISSI@N project (NERC ), COST (European Cooperation in Science and Technology) Action ES1204 LoNNe (Loss of the Night Network), the Cities at Night project, Spanish Network for Light Pollution Studies, Helmholtz Association Initiative and Networking Fund, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

© 2019 by the authors. We acknowledge the support of the Spanish Network for Light Pollution Studies (MINECO AYA2011-15808-E) and also from ACTION, a project funded by the European Union H2020-SwafS-2018-1-824603. This work has been partially funded by the Spanish MICINN, (AYA2016–75808–R), by the Madrid Regional Government through the TEC2SPACE-CM Project (P2018/NMT-4291), by Xunta de Galicia/FEDER (grant ED431B 2017/64), by the EMISSI@N project (NERC grant NE/P01156X/1) and the ORISON project (H2020-INFRASUPP-2015-2), the Cities at Night project, the European Union’s Horizon 2020 research and innovation program under grant agreement no. 689443 via project GEOEssential, FPU grant from the Ministerio de Ciencia y Tecnologia and F. Sánchez de Miguel., Night-time lights interact with human physiology through different pathways starting at the retinal layers of the eye; from the signals provided by the rods; the S-, L- and M-cones; and the intrinsically photosensitive retinal ganglion cells (ipRGC). These individual photic channels combine in complex ways to modulate important physiological processes, among them the daily entrainment of the neural master oscillator that regulates circadian rhythms. Evaluating the relative excitation of each type of photoreceptor generally requires full knowledge of the spectral power distribution of the incoming light, information that is not easily available in many practical applications. One such instance is wide area sensing of public outdoor lighting; present-day radiometers onboard Earth-orbiting platforms with sufficient nighttime sensitivity are generally panchromatic and lack the required spectral discrimination capacity. In this paper, we show that RGB imagery acquired with off-the-shelf digital single-lens reflex cameras (DSLR) can be a useful tool to evaluate, with reasonable accuracy and high angular resolution, the photoreceptoral inputs associated with a wide range of lamp technologies. The method is based on linear regressions of these inputs against optimum combinations of the associated R, G, and B signals, built for a large set of artificial light sources by means of synthetic photometry. Given the widespread use of RGB imaging devices, this approach is expected to facilitate the monitoring of the physiological effects of light pollution, from ground and space alike, using standard imaging technology., Unión Europea. H2020, Ministerio de Economía y Competitividad (MINECO), Ministerio de Ciencia e Innovación (MICINN), Comunidad de Madrid, Xunta de Galicia/FEDER, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Night-time lights interact with human physiology through different pathways starting at the retinal layers of the eye; from the signals provided by the rods; the S-, L- and M-cones; and the intrinsically photosensitive retinal ganglion cells (ipRGC). These individual photic channels combine in complex ways to modulate important physiological processes, among them the daily entrainment of the neural master oscillator that regulates circadian rhythms. Evaluating the relative excitation of each type of photoreceptor generally requires full knowledge of the spectral power distribution of the incoming light, information that is not easily available in many practical applications. One such instance is wide area sensing of public outdoor lighting; present-day radiometers onboard Earth-orbiting platforms with sufficient nighttime sensitivity are generally panchromatic and lack the required spectral discrimination capacity. In this paper, we show that RGB imagery acquired with off-the-shelf digital single-lens reflex cameras (DSLR) can be a useful tool to evaluate, with reasonable accuracy and high angular resolution, the photoreceptoral inputs associated with a wide range of lamp technologies. The method is based on linear regressions of these inputs against optimum combinations of the associated R, G, and B signals, built for a large set of artificial light sources by means of synthetic photometry. Given the widespread use of RGB imaging devices, this approach is expected to facilitate the monitoring of the physiological effects of light pollution, from ground and space alike, using standard imaging technology.