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X-WR-CALNAME:Osservatorio Astrofisico di Catania
X-ORIGINAL-URL:https://www.oact.inaf.it
X-WR-CALDESC:Eventi per Osservatorio Astrofisico di Catania
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DTSTART:20250101T000000
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BEGIN:VEVENT
DTSTART;TZID=UTC:20250403T103000
DTEND;TZID=UTC:20250403T113000
DTSTAMP:20260421T064355
CREATED:20250327T154317Z
LAST-MODIFIED:20250404T180222Z
UID:17907-1743676200-1743679800@www.oact.inaf.it
SUMMARY:Probing Impacts of Stellar Variability within HST WFC3/STIS and Ariel Tier 2 and Tier 3 Observations with Activity Metrics
DESCRIPTION:Recording: https://www.oact.inaf.it/seminars/ \nDATE:  Thursday\, April 3\, 11:00 a.m. \nORGANIZER: INAF-OACT \nLOCATION: AULA OVEST (INAF-OACT) + remote \nLink for the remote audience:https://meet.google.com/wvf-uwxo-oyj \nSPEAKER: Alexandra Thompson (Department of Physics and Astronomy\, University College London) \nABSTRACT:Stellar activity produces two main diagnostics within low-resolution exoplanet transmission spectra. Its highly chromatic nature imparts trends in the underlying spectrum that become most noticeable at shorter wavelengths due to the increased contrast between the flux from the active regions (i.e. spots and/or faculae) and the quiet photosphere. The second characteristic is that activity is inherently time-variable\, predominantly modulated by stellar rotation as active regions rotate into and out of view but also with contributions from longer timescales of evolution/decay and even long-term activity cycles e.g. maxima and minima (although certain configurations e.g. polar spots and active latitudes will be more resistant to this). This variability can reveal itself through subsequent observations of the system and is both useful and challenging; it can further help us to identify and constrain potential contamination but also means that observations at different epochs may require individual corrections before they can robustly be combined and analysed together which will become increasingly difficult for smaller planets as the SNR of each visit progressively decreases. In this seminar I will present how both diagnostics have been used with archival HST WFC3 and STIS datasets to create two new activity metrics that are highly complementary to existing indicators. I will also show preliminary results surrounding how this work is being extended to Tier 2 and Tier 3 Ariel simulations to explore how stellar variability will impact our ability to stack visits to obtain the required SNR for these tiers. \n  \nA few rules:— before joining\, make sure you are using your institutional inaf.it account if you have one (otherwise we will grant you permission to join)— please do not forget to mute your microphone and switch off your webcam when access the virtual room— for questions leave a message in the chat\, the answers at the end of the webinar— the seminar will be recorded\, so if you are interested in it\, please contact us to get the link to the registration.
URL:https://www.oact.inaf.it/event/probing-impacts-of-stellar-variability-within-hst-wfc3-stis-and-ariel-tier-2-and-tier-3-observations-with-activity-metrics/
LOCATION:Sede A. Riccò\, Via Santa Sofia 78\, Catania
CATEGORIES:Eventi & Seminari
ATTACH;FMTTYPE=image/jpeg:https://www.oact.inaf.it/wp-content/uploads/2025/03/CataniaSeminarTitleSlide2025.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250407T110000
DTEND;TZID=UTC:20250407T120000
DTSTAMP:20260421T064356
CREATED:20250405T091539Z
LAST-MODIFIED:20250405T091543Z
UID:17926-1744023600-1744027200@www.oact.inaf.it
SUMMARY:Non-standard signatures from CMB polarisation with an insight into the new technological challenges
DESCRIPTION:Recording: https://www.oact.inaf.it/seminars/ \nDATE:  Monday\, April 7\, 11:00 a.m. \nORGANIZER: INAF-OACT \nLOCATION: AULA OVEST (INAF-OACT) + remote \nLink for the remote audience:https://meet.google.com/wvf-uwxo-oyj \nSPEAKER: Dr. Matteo Billi (University of Catania) \nABSTRACT:In this seminar\, I will focus on non-standard signatures from CMB polarisation that may indicate the existence of new phenomena beyond the standard models of cosmology and particle physics\, from both theoretical and observational perspectives. ESA’s Planck mission has observed CMB temperature anisotropies at the cosmic variance limit\, but polarisation remains to be further investigated. CMB polarisation data are important not only because they contribute to provide tighter constraints on cosmological parameters but also because they allow the study of physical processes that would be excluded if only the CMB temperature maps were considered. I use polarisation data into account to assess the statistical significance of the anomalies currently observed only in the CMB temperature map\, and to constrain the Cosmic Birefringence (CB) effect\, which is expected in parity-violating extensions of the standard electromagnetism.Measuring CMB polarisation is technically challenging because the polarised signal is much fainter than the temperature signal\, and accurate polarisation estimates require exquisite control of systematic effects. To investigate the impact of spurious signals in upcoming CMB polarisation experiments\, I present a study of the interplay between half-wave plate (HWP) non-idealities and the beams of the instrument for the next generation of CMB experiments\, with an insight into how this instrumental contamination affects the measurement of the cosmic birefringence effect. \n  \nA few rules:— before joining\, make sure you are using your institutional inaf.it account if you have one (otherwise we will grant you permission to join)— please do not forget to mute your microphone and switch off your webcam when access the virtual room— for questions leave a message in the chat\, the answers at the end of the webinar— the seminar will be recorded\, so if you are interested in it\, please contact us to get the link to the registration.
URL:https://www.oact.inaf.it/event/non-standard-signatures-from-cmb-polarisation-with-an-insight-into-the-new-technological-challenges/
LOCATION:Sede A. Riccò\, Via Santa Sofia 78\, Catania
CATEGORIES:Eventi & Seminari
ATTACH;FMTTYPE=image/jpeg:https://www.oact.inaf.it/wp-content/uploads/2025/04/seminario_Billi.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250409T110000
DTEND;TZID=UTC:20250409T120000
DTSTAMP:20260421T064356
CREATED:20250408T170352Z
LAST-MODIFIED:20250408T170355Z
UID:17939-1744196400-1744200000@www.oact.inaf.it
SUMMARY:Line shape modeling for the characterization of magnetized plasmas in fusion research and astrophysics
DESCRIPTION:Recording: https://www.oact.inaf.it/seminars/ \nDATE: Wednesday\, April 9\, 11:00 a.m. \nORGANIZER: INAF-OACT \nLOCATION: AULA OVEST (INAF-OACT) + remote \nLink for the remote audience:https://meet.google.com/wvf-uwxo-oyj \nSPEAKER: Joel Rosato (Aix-Marseille Université – France) \nABSTRACT:In this talk\, we report on a selection of issues present in the elaboration of spectroscopic models for magnetized plasma diagnostic. A focus is put on tokamak edge and white dwarf atmosphere plasma conditions. In both cases\, the observed spectra exhibit clean lines\, either in absorption or in emission\, denoting the presence of neutral species (atoms). An analysis of the line shape and intensity yields information on the plasma parameters provided a suitable physical model is used. We first discuss in detail the physical mechanisms underlying the broadening of the spectral lines due to the plasma microfield (Stark effect)\, and we next report on models and codes that have been developed in our group at the PIIM laboratory. Applications to the fitting of observed spectra – both in magnetic fusion and astrophysics – are presented. Motivated by current research trends\, we also discuss specific issues related to the presence of strong external magnetic field (Zeeman effect etc.) and report on some recent works done in atomic physics for the improvement of line shape models. \n  \nA few rules:— before joining\, make sure you are using your institutional inaf.it account if you have one (otherwise we will grant you permission to join)— please do not forget to mute your microphone and switch off your webcam when access the virtual room— for questions leave a message in the chat\, the answers at the end of the webinar— the seminar will be recorded\, so if you are interested in it\, please contact us to get the link to the registration.
URL:https://www.oact.inaf.it/event/line-shape-modeling-for-the-characterization-of-magnetized-plasmas-in-fusion-research-and-astrophysics/
LOCATION:Sede A. Riccò\, Via Santa Sofia 78\, Catania
CATEGORIES:Eventi & Seminari
ATTACH;FMTTYPE=image/jpeg:https://www.oact.inaf.it/wp-content/uploads/2025/04/Seminario_Rosato.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250414T110000
DTEND;TZID=UTC:20250414T120000
DTSTAMP:20260421T064356
CREATED:20250412T163324Z
LAST-MODIFIED:20250412T163327Z
UID:17962-1744628400-1744632000@www.oact.inaf.it
SUMMARY:Elucidating diffuse Galactic synchrotron emission for precision 21cm and CMB cosmology
DESCRIPTION:Recording: https://www.oact.inaf.it/seminars/ \nDATE: Monday\, April 14\, 11:00 a.m. \nORGANIZER: INAF-OACT \nLOCATION: AULA OVEST (INAF-OACT) + remote \nLink for the remote audience:https://meet.google.com/wvf-uwxo-oyj \nSPEAKER: Dr. Melis O. Irfan (IoA\, University of Cambridge) \nABSTRACT:The next generation of Cosmic Microwave Background experiments are poised to probe the inflationary period of the Universe through the measurement of primordial B-modes\, whilst 21cm experiments are observing the reionization history of the early Universe and formation of Large-Scale Structure through the mapping of neutral hydrogen. These two complementary fields span the radio to microwave frequency regimes and share a pivotal data reduction task: foreground component separation.Diffuse Galactic synchrotron emission is the dominant foreground for arcmin/degree scale cosmological surveys operating across MHz frequencies in intensity\, and at all frequencies under 60 GHz in polarised intensity. In this talk I will present measurements of the synchrotron spectral index and curvature between 73 MHz and 1 GHz through the combined use of pilot MeerKLASS\, Haslam\, Maipu/MU and LWA data. I will discuss the advances that can be made to component separation algorithms thanks to more sophisticated foreground emission modelling and will present a spatially complex\, all-sky model of the synchrotron spectral index formed using convolutional neural networks trained on sets of both high- and low-resolution empirical data. Such advances will\, and already are\, expanding our understanding of the spatial and spectral form of this complex emission; ameliorating component separation for both CMB and 21cm intensity mapping experiments. \n  \nA few rules:— before joining\, make sure you are using your institutional inaf.it account if you have one (otherwise we will grant you permission to join)— please do not forget to mute your microphone and switch off your webcam when access the virtual room— for questions leave a message in the chat\, the answers at the end of the webinar— the seminar will be recorded\, so if you are interested in it\, please contact us to get the link to the registration.
URL:https://www.oact.inaf.it/event/elucidating-diffuse-galactic-synchrotron-emission-for-precision-21cm-and-cmb-cosmology/
LOCATION:Sede A. Riccò\, Via Santa Sofia 78\, Catania
CATEGORIES:Eventi & Seminari
ATTACH;FMTTYPE=image/jpeg:https://www.oact.inaf.it/wp-content/uploads/2025/04/promo_page-0001.jpg
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250430T110000
DTEND;TZID=UTC:20250430T120000
DTSTAMP:20260421T064356
CREATED:20250428T210420Z
LAST-MODIFIED:20250428T210924Z
UID:18011-1746010800-1746014400@www.oact.inaf.it
SUMMARY:Precision Meter-wavelength Polarimetry with the Very Large Array
DESCRIPTION:Recording: https://www.oact.inaf.it/seminars/ \nDATE: Wednesday\, April 30\, 11:00 a.m. \nORGANIZER: INAF-OACT \nLOCATION: AULA OVEST (INAF-OACT) + remote \nLink for the remote audience:https://meet.google.com/wvf-uwxo-oyj \nSPEAKER: Rick Perley (National Radio Astronomy Observatory – USA) \nABSTRACT:Accurate imaging polarimetry at meter wavelengths requires removal of the highly variable ionospheric Faraday rotation (IFRM) with an accuracy of 0.1 rad/m^2 or better. Models to estimate the VTEC using GNSS timing data\, combined with global terrestrial magnetic field models have been developed over the past 25 years.  Estimating the accuracy of these models requires observations of a source of known intrinsic electric vector position angle (EVPA) over a wide rage of ionospheric conditions.Using eight VLA polarimetric observations of the moon spanning ten years using the VLA’s P-band (295 — 445 MHz) receivers\, we have tested the accuracy of seven global IONEX models produced by the AIPS program TECOR\, and the regional model derived by ALBUS.All seven global models overestimate the IFRM\, typically by 0.5 to 1.0 rad/m^2 — a value which remains constant over many hours\, including day — night transitions.  The ‘ALBUS’ model\, which uses GNSS ground station data within ~300 km of the requested site\, generates predictions which are always the closest — usually with 0.2 rad/m^2— to the observed values. \n  \nA few rules:— before joining\, make sure you are using your institutional inaf.it account if you have one (otherwise we will grant you permission to join)— please do not forget to mute your microphone and switch off your webcam when access the virtual room— for questions leave a message in the chat\, the answers at the end of the webinar— the seminar will be recorded\, so if you are interested in it\, please contact us to get the link to the registration.
URL:https://www.oact.inaf.it/event/precision-meter-wavelength-polarimetry-with-the-very-large-array/
LOCATION:Sede A. Riccò\, Via Santa Sofia 78\, Catania
CATEGORIES:Eventi & Seminari
ATTACH;FMTTYPE=image/jpeg:https://www.oact.inaf.it/wp-content/uploads/2025/04/Locandine-eventi-OACT-2.jpg
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