Person: Nievas Rosillo, Mireia
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First Name
Mireia
Last Name
Nievas Rosillo
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Estructura de la Materia, Física Térmica y Electrónica
Area
Identifiers
5 results
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Item PySQM the UCM open source software to read, plot and store data from SQM photometers(2014) Nievas Rosillo, Mireia; Zamorano Calvo, JaimeA multi platform software (PySQM) has been designed to read, store and plot data from Unihedron SQM-LE and SQM-LU photometers. It is intended to record night sky brightness data obtained with fixed SQM photometers. PySQM is distributed as open source software.Item Zernike power spectra of clear and cloudy light-polluted urban night skies(Applied optics, 2015) Bará, Salvador; Tilve, Victor; Nievas Rosillo, Mireia; Sánchez de Miguel, Alejandro; Zamorano Calvo, JaimeThe 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.Item Report of the 2014 LoNNe intercomparison campaign(2015) Bará, Salvador; Espey, Brian; Falchi, Fabio; Kyba, Christopher C. M.; Nievas Rosillo, Mireia; Pescatori, Paolo; Ribas, Salvador; Sánchez de Miguel, Alejandro; Staubmann, Philipp; Tapia Ayuga, Carlos; Wuchterl, Günther; Zamorano Calvo, JaimeThe 2014 LoNNe (Loss of the Night Network) intercomparison campaign is the second of four campaigns planned during EU COST Action ES1204. The goal of these campaigns is to understand systematic uncertainty inherent in observations of skyglow (light pollution). An innovation of this year’s campaign was to take measurements with many of the nstruments at two sites: an urban location and a location far from artificial lights. This report summarizes the eeting, and also provides three recommendations for obtaining and analyzing handheld SQM observations. The UCM group of Astronomical Instrumentation and Extragalactic Astronomy (GUAIX) hosted the meeting at the Physics building of Universidad Complutense de Madrid (UCM). A meeting room at Departamento de Astrofísica y CC. de la Atmósfera and the astronomical observatory (Observatorio UCM) were prepared in advance. In particular, a tailor made station to set the SQM and other photometer devices was installed on the roof of the Physics building. The Laboratorio de Investigación Científica Avanzada (LICA) was used to test and characterize a number of devices and filters.Item Worldwide variations in artificial skyglow(Scientific reports, 2015) Nievas Rosillo, Mireia; Zamorano Calvo, Jaime; otros, ...Despite constituting a widespread and significant environmental change, understanding of artificial nighttime skyglow is extremely limited. Until now, published monitoring studies have been local or regional in scope, and typically of short duration. In this first major international compilation of monitoring data we answer several key questions about skyglow properties. Skyglow is observed to vary over four orders of magnitude, a range hundreds of times larger than was the case before artificial light. Nearly all of the study sites were polluted by artificial light. A non-linear relationship is observed between the sky brightness on clear and overcast nights, with a change in behavior near the rural to urban landuse transition. Overcast skies ranged from a third darker to almost 18 times brighter than clear. Clear sky radiances estimated by the World Atlas of Artificial Night Sky Brightness were found to be overestimated by similar to 25%; our dataset will play an important role in the calibration and ground truthing of future skyglow models. Most of the brightly lit sites darkened as the night progressed, typically by similar to 5% per hour. The great variation in skyglow radiance observed from site-to-site and with changing meteorological conditions underlines the need for a long-term international monitoring program.Item Extreme HBL behavior of Markarian 501 during 2012(Astronomy & Astrophysics, 2018) Barrio Uña, Juan Abel; Contreras González, José Luis; Domínguez Díaz, Alberto; Carreto Fidalgo, David Friedrich; Fonseca González, Mª Victoria; López Moya, Marcos; Miranda Pantoja, José Miguel; Nievas Rosillo, Mireia; otros, ...Aims. We aim to characterize the multiwavelength emission from Markarian 501 (Mrk 501), quantify the energy-dependent variability, study the potential multiband correlations, and describe the temporal evolution of the broadband emission within leptonic theoretical scenarios. Methods. We organized a multiwavelength campaign to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on board the Swift and Fermi spacecraft, and the telescopes operated by the GASP-WEBT collaboration. Results. Mrk 501 showed a very high energy (VHE) gamma-ray flux above 0.2 TeV of similar to 0.5 times the Crab Nebula flux (CU) for most of the campaign. The highest activity occurred on 2012 June 9, when the VHE flux was similar to 3 CU, and the peak of the high-energy spectral component was found to be at similar to 2 TeV. Both the X-ray and VHE gamma-ray spectral slopes were measured to be extremely hard, with spectral indices <2 during most of the observing campaign, regardless of the X-ray and VHE flux. This study reports the hardest Mrk 501 VHE spectra measured to date. The fractional variability was found to increase with energy, with the highest variability occurring at VHE. Using the complete data set, we found correlation between the X-ray and VHE bands; however, if the June 9 flare is excluded, the correlation disappears (significance <3 sigma) despite the existence of substantial variability in the X-ray and VHE bands throughout the campaign. Conclusions. The unprecedentedly hard X-ray and VHE spectra measured imply that their low- and high-energy components peaked above 5 keV and 0.5 TeV, respectively, during a large fraction of the observing campaign, and hence that Mrk 501 behaved like an extreme high-frequency-peaked blazar (EHBL) throughout the 2012 observing season. This suggests that being an EHBL may not be a permanent characteristic of a blazar, but rather a state which may change over time. The data set acquired shows that the broadband spectral energy distribution (SED) of Mrk 501, and its transient evolution, is very complex, requiring, within the framework of synchrotron self-Compton (SSC) models, various emission regions for a satisfactory description. Nevertheless the one-zone SSC scenario can successfully describe the segments of the SED where most energy is emitted, with a significant correlation between the electron energy density and the VHE gamma-ray activity, suggesting that most of the variability may be explained by the injection of high-energy electrons. The one-zone SSC scenario used reproduces the behavior seen between the measured X-ray and VHE gamma-ray fluxes, and predicts that the correlation becomes stronger with increasing energy of the X-rays.