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AutoSourceID-Light : Fast optical source localization via U-Net and Laplacian of Gaussian
F. Stoppa, P. Vreeswijk, S. Bloemen, S. Bhattacharyya, S Caron, G. Jóhannesson, R. Ruiz de Austri, C. Van den Oetelaar, G. Zaharijas, P.J. Groot, E. Cator, G. Nelemans, 2022, original scientific article

Abstract: Aims: With the ever-increasing survey speed of optical wide-field telescopes and the importance of discovering transients when they are still young, rapid and reliable source localization is paramount. We present AutoSourceID-Light (ASID-L), an innovative framework that uses computer vision techniques that can naturally deal with large amounts of data and rapidly localize sources in optical images. Methods: We show that the ASID-L algorithm based on U-shaped networks and enhanced with a Laplacian of Gaussian filter provides outstanding performance in the localization of sources. A U-Net network discerns the sources in the images from many different artifacts and passes the result to a Laplacian of Gaussian filter that then estimates the exact location. Results: Using ASID-L on the optical images of the MeerLICHT telescope demonstrates the great speed and localization power of the method. We compare the results with SExtractor and show that our method outperforms this more widely used method rapidly detects more sources not only in low and mid-density fields, but particularly in areas with more than 150 sources per square arcminute. The training set and code used in this paper are publicly available.
Keywords: astronomical databases, data analysis, image processing
Published in RUNG: 23.01.2023; Views: 614; Downloads: 0
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Tidal Disruption Events seen through the eyes of Vera C. Rubin Observatory
Katja Bučar Bricman, 2021, doctoral dissertation

Abstract: Tidal Disruption Events (TDEs) are rare transients, which are considered to be promising tools in probing supermassive black holes (SMBHs) and their environments in quiescent galaxies, accretion physics, and jet formation mechanisms. The majority of $\approx$ 60 detected TDEs has been discovered with large field of view time-domain surveys in the last two decades. Currently, about 10 TDEs are discovered per year, and we expect this number will increase largely once the Legacy Survey of Space and Time (LSST) at Vera C. Rubin Observatory begins its observations. In this work we demonstrate and explore the capabilities of the LSST to study TDEs. To begin with, we simulate LSST observations of TDEs over $10$ years of survey duration by including realistic SED models from MOSFiT into the simulation framework of the LSST. SEDs are then converted into observed fluxes and light curves are simulated with the LSST observing strategy minion_1016. Simulated observations are used to estimate the number of TDEs the LSST is expected to observe and to assess the possibility of probing the SMBH mass distribution in the Universe with the observed TDE sample. We find that the LSST has a potential of observing ~1000 TDEs per year, the exact number depending on the SMBH mass distribution and the adopted observing strategy. In spite of this large number, we find that probing the SMBH mass distribution with LSST observed TDEs will not be straightforward, especially at the low-mass end. This is largely attributed to the fact that TDEs caused by low-mass black holes ($\le 10^6 M_\odot$) are less luminous and shorter than TDEs by heavier SMBHs ($> 10^6 M_\odot$), and the probability of observationally missing them with LSST is higher. Second, we built a MAF TDE metric for photometric identification of TDEs based on LSST data. We use the metric to evaluate the performance of different proposed survey strategies in identifying TDEs with pre-defined identification requirements. Since TDEs are blue in color for months after peak light, which separates them well from SNe and AGN, we include u-band observations as one of the criteria for a positive identification. We find that the number of identified TDEs strongly depends of the observing strategy and the number of u-band visits to a given field in the sky. Observing strategies with a larger number of u-band observations perform significantly better. For these strategies up to 10% of LSST observed TDEs satisfy the identification requirements.
Keywords: Ground-based ultraviolet, optical and infrared telescopes Astronomical catalogs, atlases, sky surveys, databases, retrieval systems, archives, Black holes, Galactic nuclei (including black holes), circumnuclear matter, and bulges, Infall, accretion, and accretion disks
Published in RUNG: 03.01.2022; Views: 1851; Downloads: 46
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Digitalizacija kulturne dediščine v dveh projektih programa Študentski inovativni projekti za družbeno korist : digitalizacija, korespondence, elektronske zbirke, aleksandrinke, študentski projekt, digitalna humanistika
Katja Mihurko Poniž, Narvika Bovcon, Aneta Ivanovska, Tina Smrekar, 2020, published scientific conference contribution

Abstract: Članek predstavi dva projekta digitalizacije in spletne predstavitve kulturne dediščine aleksandrink in različnih skupin žensk, ki so večinsko povezane s primorskim in notranjskim geografskim prostorom: v prvem primeru gre za bazo podatkov o aleksandrinkah, v drugem pa za digitalizirano pisemsko dediščino. Program Študentskih inovativnih projektov za družbeno korist je odlična platforma za pilotske projekte s področja digitalne humanistike, saj predvideva interdisciplinarno delovno skupino študentov in mentorjev ter v korist lokalne skupnosti usmerjene praktične rezultate projekta.
Keywords: digitisation, correspondences, electronic databases, aleksandrinke, student project, digital humanities
Published in RUNG: 29.09.2020; Views: 2573; Downloads: 0
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Un approccio graph-theoretic alla progettazione di basi di dati XML guidato dal tipo e dalla frequenza delle interrogazioni.
Federico Torzo, 2015, undergraduate thesis

Keywords: databases design, XML schema, algorithms, graph theory
Published in RUNG: 12.07.2017; Views: 3573; Downloads: 0
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