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Hampf, D., Rowell, G., Wild, N., Sudholz, T., Horns, D., & Tluczykont, M. (2011). Measurement of night sky brightness in southern Australia. Advances in Space Research, 48(6), 1017–1025.
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 Fowlerâs 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 Ã 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 Ã 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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Noll, S., Kausch, W., Barden, M., Jones, A. M., Szyszka, C., Kimeswenger, S., et al. (2012). An atmospheric radiation model for Cerro Paranal: I. The optical spectral range*. A&A, 543, A92.
Abstract: Aims. The Earthâs atmosphere affects ground-based astronomical observations. Scattering, absorption, and radiation processes deteriorate the signal-to-noise ratio of the data received. For scheduling astronomical observations it is, therefore, important to accurately estimate the wavelength-dependent effect of the Earthâs atmosphere on the observed flux.
Methods. In order to increase the accuracy of the exposure time calculator of the European Southern Observatoryâs (ESO) Very Large Telescope (VLT) at Cerro Paranal, an atmospheric model was developed as part of the Austrian ESO In-Kind contribution. It includes all relevant components, such as scattered moonlight, scattered starlight, zodiacal light, atmospheric thermal radiation and absorption, and non-thermal airglow emission. This paper focuses on atmospheric scattering processes that mostly affect the blue (<0.55 μm) wavelength regime, and airglow emission lines and continuum that dominate the red (>0.55 μm) wavelength regime. While the former is mainly investigated by means of radiative transfer models, the intensity and variability of the latter is studied with a sample of 1186 VLT FORS 1 spectra.
Results. For a set of parameters such as the object altitude angle, Moon-object angular distance, ecliptic latitude, bimonthly period, and solar radio flux, our model predicts atmospheric radiation and transmission at a requested resolution. A comparison of our model with the FORS 1 spectra and photometric data for the night-sky brightness from the literature, suggest a model accuracy of about 20%. This is a significant improvement with respect to existing predictive atmospheric models for astronomical exposure time calculators.
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Puschnig, J., Posch, T., & Uttenthaler, S. (2014). Night sky photometry and spectroscopy performed at the Vienna University Observatory. Journal of Quantitative Spectroscopy and Radiative Transfer, 139, 64–75.
Abstract: We present night sky brightness measurements performed at the Vienna University Observatory and at the Leopold-Figl-Observatorium für Astrophysik, which is located about 35 km to the southwest of Vienna. The measurements have been performed with Sky Quality Meters made by Unihedron. They cover a time span of roughly one year and have been carried out every night, yielding a luminance value every 7 s and thus delivering a large amount of data. In this paper, the level of skyglow in Vienna, which ranges from 15 to 19.25 magSQM arcsec−2 is presented for the very first time in a systematic way. We discuss the influence of different environmental conditions on the night sky brightness and implications for human vision. We show that the circalunar rhythm of night sky brightness is almost extinguished at our observatory due to light pollution.
Additionally, we present spectra of the night sky in Vienna, taken with a 0.8 m telescope. The goal of these spectroscopic measurements was to identify the main types of light sources and the spectral lines which cause the skyglow in Vienna. It turned out that fluorescent lamps are responsible for the strongest lines of the night sky above Vienna (e.g. lines at 546 nm and at 611 nm).
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