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Author |
Hampf, D.; Rowell, G.; Wild, N.; Sudholz, T.; Horns, D.; Tluczykont, M. |
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Title |
Measurement of night sky brightness in southern Australia |
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Journal Article |
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Year |
2011 |
Publication |
Advances in Space Research |
Abbreviated Journal |
Advances in Space Research |
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Volume |
48 |
Issue |
6 |
Pages |
1017-1025 |
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Keywords |
Observatories and site testing; Airglow and aurorae; Photometric, polarimetric, and spectroscopic instrumentation |
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Abstract |
Night sky brightness is a major source of noise both for Cherenkov telescopes as well as for wide-angle Cherenkov detectors. Therefore, it is important to know the level of night sky brightness at potential sites for future experiments.
The measurements of night sky brightness presented here were carried out at Fowler’s Gap, a research station in New South Wales, Australia, which is a potential site for the proposed TenTen Cherenkov telescope system and the planned wide-angle Cherenkov detector system HiSCORE.
A portable instrument was developed and measurements of the night sky brightness were taken in February and August 2010. Brightness levels were measured for a range of different sky regions and in various spectral bands.
The night sky brightness in the relevant wavelength regime for photomultipliers was found to be at the same level as measured in similar campaigns at the established Cherenkov telescope sites of Khomas, Namibia, and at La Palma. The brightness of dark regions in the sky is about 2 × 1012 photons/(s sr m2) between 300 nm and 650 nm, and up to four times brighter in bright regions of the sky towards the galactic plane. The brightness in V band is 21.6 magnitudes per arcsec2 in the dark regions. All brightness levels are averaged over the field of view of the instrument of about 1.3 × 10−3 sr.
The spectrum of the night sky brightness was found to be dominated by longer wavelengths, which allows to apply filters to separate the night sky brightness from the blue Cherenkov light. The possible gain in the signal to noise ratio was found to be up to 1.2, assuming an ideal low-pass filter. |
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Department of Physics, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany |
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0273-1177 |
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IDA @ john @ |
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189 |
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Author |
Falchi, F. |
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Title |
Campaign of sky brightness and extinction measurements using a portable CCD camera: Sky brightness and extinction measurements |
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Journal Article |
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Year |
2011 |
Publication |
Monthly Notices of the Royal Astronomical Society |
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412 |
Issue |
1 |
Pages |
33-48 |
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Keywords |
sky brightness; monitoring; light pollution; skyglow |
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Abstract |
In this paper, we present the results of a 12-yr campaign devoted to monitoring the sky brightness affected by different levels of light pollution. Different sites characterized by different altitudes and atmospheric transparency have been considered. The standard photometric Johnson B and V bands were used. An extinction measurement was performed for each site and each night, along with a calibration of the instrument. These measurements have allowed us to build sky brightness maps of the hemisphere above each observing site; each map contains up to 200 data points spread around the sky. We have found a stop in zenith sky brightness growth at the two sites where a time series exists. Using zenith sky brightness measurements taken with and without extensive snow coverage, we weighted the importance of direct versus indirect flux in producing sky glow at several sites. |
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0035-8711 |
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IDA @ john @ |
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190 |
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Femia, N.; Fortunato, M.; Vitelli, M. |
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Title |
Light-to-Light: PV-Fed LED Lighting Systems |
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Journal Article |
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2013 |
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IEEE Transactions on Power Electronics |
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IEEE Trans. Power Electron. |
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28 |
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8 |
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4063-4073 |
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Keywords |
light-to-light systems; outdoor lighting; lighting technology; LED; LED lighting; photovoltaics; PV |
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Abstract |
This paper discusses the principle of operation, dynamic modeling, and control design for light-to-light (LtL) systems, whose aim is to directly convert the sun irradiation into artificial light. The system discussed in this paper is composed by a photovoltaic (PV) panel, an LED array, a dc-dc converter dedicated to the maximum power point tracking of the PV panel and a dc-dc converter dedicated to drive the LEDs array. A system controller is also included, whose goal is to ensure the matching between the maximum available PV power and the LED power by means of a low-frequency LEDs dimming. An experimental design example is discussed to illustrate the functionalities of the LtL system. |
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Dipt. di Ing. Elettron. e Ing. Inf., Univ. of Salerno, Salerno, Italy |
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0885-8993 |
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IDA @ john @ |
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331 |
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Tähkämö, L.; Ylinen, A.; Puolakka, M.; Halonen, L. |
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Title |
Life cycle cost analysis of three renewed street lighting installations in Finland |
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Journal Article |
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Year |
2012 |
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The International Journal of Life Cycle Assessment |
Abbreviated Journal |
Int J Life Cycle Assess |
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17 |
Issue |
2 |
Pages |
154-164 |
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Keywords |
LED; LED lighting; Life cycle costs; Light-emitting diode; Payback time; Road lighting; Street lighting |
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Abstract |
Purpose
Outdoor lighting is facing major changes due to the EU legislation on ecodesign of energy-related products, such as the ban of high-pressure mercury (HPM) lamps widely used in outdoor lighting. This article presents life cycle costs (LCC) of three examples of replacing HPM lamps in street lighting in Finland. The purpose of the article is to assess how the development of light-emitting diode (LED) technology affects LCCs and how the division of LCCs differentiates in the cases.
Methods
Two of the cases change from HPM lamps to high-pressure sodium (HPS) lamps. In the third one, HPM lamps are replaced by LED luminaires. LED technology predictions of price and luminous efficacy are included in different scenarios. The calculations consider investment and operating costs and residual value.
Results and discussion
Each replacement reduces the energy costs approximately by half compared to the original HPM lamp luminaires. Energy costs dominate the LCCs of the HPS lamp installations while investment cost is the dominating one in LED luminaire case. The changes from HPM to HPS technology have payback times lower than 9 years, while changing to LED luminaires is not economic. However, the electricity price is low in this case. The payback times of LED installations can be as low as 6 years if the luminaires are installed in 2015 and an average electricity price is used.
Conclusions
The LCCs of real-life case studies cannot be directly compared, since their luminous properties vary. There is a need for a method for including luminous properties in LCC calculations. |
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Lighting Unit, School of Electrical Engineering, Aalto University, P.O. Box 13340, 00076, Aalto, Finland |
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0948-3349 |
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IDA @ john @ |
Serial |
332 |
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Author |
Duriscoe, D.M.; Luginbuhl, C.B.; Moore, C.W. |
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Title |
Measuring Night-Sky Brightness with a Wide-Field CCD Camera |
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Journal Article |
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Year |
2007 |
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Publications of the Astronomical Society of the Pacific |
Abbreviated Journal |
Publ Astron Soc Pac |
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Volume |
119 |
Issue |
852 |
Pages |
192-213 |
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Keywords |
light pollution; light at night; skyglow; monitoring; measurement; CCD |
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We describe a system for rapidly measuring the brightness of the night sky using a mosaic of CCD images obtained with a low-cost automated system. The portable system produces millions of independent photometric measurements covering the entire sky, enabling the detailed characterization of natural sky conditions and light domes produced by cities. The measurements are calibrated using images of standard stars contained within the raw data, producing results closely tracking the Johnson V astronomical standard. The National Park Service has collected hundreds of data sets at numerous parks since 2001 and is using these data for the protection and monitoring of the night-sky visual resource. This system also allows comprehensive characterization of sky conditions at astronomical observatories. We explore photometric issues raised by the broadband measurement of the complex and variable night-sky spectrum, and potential indices of night-sky quality. |
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0004-6280 |
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IDA @ john @ |
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193 |
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