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MELCHIORS: The Mercator Library of High Resolution Stellar Spectroscopy
Get PDFAims. Over the past decades, libraries of stellar spectra have been used in a large variety of science cases, including as sources of reference spectra for a given object or a given spectral type. Despite the existence of large libraries and the increasing number of projects of large-scale spectral surveys, there is to date only one very high-resolution spectral library offering spectra from a few hundred objects from the southern hemisphere (UVES-POP). We aim to extend the sample, offering a finer coverage of effective temperatures and surface gravity with a uniform collection of spectra obtained in the northern hemisphere. Methods. Between 2010 and 2020, we acquired several thousand echelle spectra of bright stars with the Mercator-HERMES spectrograph located in the Roque de Los Muchachos Observatory in La Palma, whose pipeline offers high-quality data reduction products. We have also developed methods to correct for the instrumental response in order to approach the true shape of the spectral continuum. Additionally, we have devised a normalisation process to provide a homogeneous normalisation of the full spectral range for most of the objects. Results. We present a new spectral library consisting of 3256 spectra covering 2043 stars. It combines high signal-to-noise and high spectral resolution over the entire range of effective temperatures and luminosity classes. The spectra are presented in four versions: raw, corrected from the instrumental response, with and without correction from the atmospheric molecular absorption, and normalised (including the telluric correction)
Towards FAIR Digital Objects for Heritage Science Data
Get PDFHeritage science is an interdisciplinary field that involves the scientific study of cultural and natural heritage. It entails collecting and producing a wide variety of data, including descriptions of objects and sites, samples, sampling locations, scientific instrumentation, analytical methods, conservation and restoration records, environmental monitoring data, documentation, and digital representations. E-RIHS (European Research Infrastructure for Heritage Science) is a collaborative effort among key players in Europe and beyond, on the verge of becoming an operational European Research Infrastructure Consortium (ERIC). The focus is on cooperation, for which interoperability of processes and the need for FAIR and linked data are indispensable prerequisites.
This presentation will cover ongoing efforts to advance the realisation of digital objects for encapsulating and describing data collected in E-RIHS and may serve as a framework for heritage science data in general. The work was carried out within the scope of IPERION HS, the last of the past projects building towards E-RIHS. The focus is on minimising documentation burden while enhancing interoperability through the creation of reusable, linkable digital objects.
A systematic, bottom-up methodology is employed to break down the entire metadata environment of heritage science into accessible individual digital objects. These objects are semantically consistent and correspond to separate entities that are linked together to form the data flow involved in a research project. The models are meticulously modelled, taking into account all essential metadata associated with them. Existing data and metadata gathered during previous and current E-RIHS-related projects, as well as similar models and standards defined in other research domains, were studied wherever possible.
The Simple Dynamic Modelling tool, developed by the National Gallery, was extensively used to facilitate the development of the models and their visualisation. The models can be found in the E-RIHS organisation on GitHub. They are revised frequently as related models evolve, ensuring efficient linking between the models and avoiding duplication of metadata.
The models are then converted into JSON Schema, which after validation, can be visualized and evaluated using commonly used software libraries that generate web-forms from JSON schema documents. An instance of Cordra, open source software for managing digital objects instance and implementing the Digital Object Interface Protocol (DOIP), was created for E-RIHS to serve as a searchable database and metadata repository for heritage science digital objects. The ultimate goal is to pave the way for a future where information is not only preserved but also effortlessly navigable and actionable within the broader heritage scientific landscape
Technical Expertise Report ref. 69, 70, 71, 72, 73, 74, 75, 76, 77 - Applicant: Royal Museum for Central Africa, Service Ethnography, 12/11/2014
No full textThe Valuable Plurality of the Citizen Sciences
No full textCitizen science is a multilayered concept. Although it is generally understood as a form of public engagement with science and technology, it can take various forms, with widely different roles for citizens. Despite this vastness, a contributory strand of citizen science dominates the field, which formally limits citizens' roles to those of data gatherers for professional scientists or experts. This has led critics to argue that citizen science is not as inclusive, socially transformative, or democratizing as its advocates claim, and to appeals by scholars, practitioners, and policymakers for more dialogue and deliberation in all stages of citizen science processes. In this piece, we share our reflections on these questions drawing on our experiences as participant observers in contributory citizen science projects in various parts of the world. Responding to the above critiques, we illustrate how such projects can have emancipatory potential in terms of impacting policy agendas, inciting behavioral change, and engaging hard -to -reach societal groups. We argue that the future of citizen science lies in pluralizing the citizen sciences by experimenting with various modes of democratic representation, participation, and deliberation
Design of a Radio Frequency Compensation System, using the Electrical Characterisation of a Multi-Transducer Acousto-Optical Tunable Filter
Get PDFAcousto-Optical Tunable Filters (AOTFs) make use of the interaction between sound and light. To generate an ultrasound diffraction grating, a Radio-Frequency (RF) signal is applied to a piezoelectric transducer. The optical pass band can be controlled by adapting the properties of this transducer and the RF-signal. To achieve more precise control of the optical spectral bandwidth, we propose to use a multi-electrode array, consisting of five consecutive transducers. The Voltage Standing Wave Ratio (VSWR) is then used to evaluate the efficiency of the coupling between the RF-signal applied to the transducer and the acousto-optical crystal. A higher VSWR indicates that more power is being reflected back and less is being absorbed by the transducer, which in turn results in a decrease in optical performance. The aim of this paper is to develop an RF driving system capable of compensating for the VSWR behavior, linked to the individual impedance matching network of each transducer. For this, the five transducer setups were electrically characterized. These measurements allow the development of an RF power compensation system, leading to an increase of applied power at the level of each transducer. Hence, the absorbed power at transducer level increases, resulting in improved optical diffraction efficiency. © 2023 Jurgen Vanhamel et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Non-destructive wood identification using X-ray µCT scanning: which resolution do we need
No full textDetecting sources of shallow tremor at neighboring volcanoes in the Virunga Volcanic Province using seismic amplitude ratio analysis (SARA)
No full textVolcano monitoring requires simple techniques to rapidly identify the cause of volcanic unrest. The so-called RSAM (real-time seismic amplitude measurements) technique, used in many observatories, is a good example of extracting information from seismograms with minimal processing. Built on a similar principle, the more recent seismic amplitude ratio analysis (SARA) technique allows locating migrating seismicity at high frequency (> 2 Hz, e.g., due to dike intrusions) under certain assumptions. However, such analysis generally requires a dense distribution of stations close to the seismic sources (depending on the magnitude) and/or station sites undisturbed by human activity. In a more straightforward and qualitative approach, computing amplitude ratios between station pairs can also allow for the detection of temporal and (2D) spatial changes of volcanic activity. In this work, we adopt such a simplified approach of SARA in order to characterize seismic tremors originating from two open-vent neighboring volcanoes, Nyiragongo and Nyamulagira, in the Virunga Volcanic Province (VVP) in the Democratic Republic of the Congo (DRC). In contrast with previous studies, we focus here on the low-frequency band (0.3 1 Hz), free from anthropogenic noise and sensitive to shallow volcanic tremors linked to intermittent or permanent intra-crater eruptive activity recorded through the large-aperture local network. We apply for the first time the SARA methodology for volcanic sources predominantly generating surface waves and propagating over long distances. The analysis is performed on more than two years of continuous seismic data. Seismic amplitude analysis in this frequency band is strongly influenced by the short-period microseisms originating from nearby Lake Kivu. Despite this diurnal to seasonal amplitude variability, SARA successfully detects continuous volcanic tremor activity and its arrest at both volcanoes. In light of these findings, we discuss the applicability of the method to the continuous, real-time detection, and characterization of long-period shallow volcanic tremor sources in this region
