AtmoHEAD 2026

28 Jul 2026, 08:00 → 30 Jul 2026, 15:00 Europe/Prague

Palacky University Olomouc

Dušan Mandát (Institute of Physics of the Czech Academy of Sciences), Jan Ebr

The atmosphere serves as a critical component for high-energy astroparticle detectors, including Imaging Atmospheric Cherenkov Telescopes (IACTs) and both ground- and space-based cosmic-ray observatories. These instruments utilize the atmosphere as a massive calorimeter, where primary particles initiate extensive air showers and generate Cherenkov and fluorescence light. Because this medium also attenuates and scatters signals before they reach the detector, precise monitoring of aerosol and molecular conditions is essential for accurate event reconstruction. Furthermore, the growing interest in atmospheric electricity has expanded the field's scope; it is now vital to understand how these electrical phenomena affect astroparticle measurements. Conversely, the high resolution and large apertures of these detectors offer a unique opportunity to study events like ELVES and TGFs. This workshop is designed to foster interdisciplinary dialogue, with dedicated sessions for collaborative discussion.

The proceedings will be published in Journal of Physics: Conference Series.

 

Important dates and deadlines: 

• registration  open/close - 1.3. 2026 - 31.5. 2026
• abstract submission deadline - 10.5. 2026
• Notification of Acceptance - 12.5.2026
• Payment deadline - 31.5.2026
• Conference dates - 28 - 30.7.2026
• Proceeding Submission - 15.8.2026

 

Tuesday 28 July

1 Registration

Laser-based tools

2 19 years of aerosol measurements with the laser facilities of the Pierre Auger Observatory and the 2025 systems upgrade

The attenuation of the fluorescence light in atmosphere due to the presence of aerosols is continuously monitored at the Pierre Auger Observatory with the two distant laser facilites, the Central Laser Facility (CLF) and the eXtreme Laser Facility (XLF). The long-time aerosol attenuation conditions measured in 19 years of operation, and used in the reconstruction of cosmic-ray events registered by the Fluorescence Detector, are presented. To ensure the capability to operate the laser facilities in the next years, they have undergone a major upgrade in 2025. The realization of the new CLF and XLF, the custom GPS board designed for the timing of the system, and the results of the first months of operation are described.

Speaker: Prof. Laura Valore (INFN Sezione di Napoli and University of Napoli Federico II)

3 Aerosol horizontal homogeneity studies with elastic lidars at the Pierre Auger Observatory

Horizontal elastic lidar shots towards the Pierre Auger Observatory array, taken every hour, are useful for measuring the homogeneity of the aerosol extinction coefficient at ground level. They also serve to parametrize the relative alignment between laser beam and the mirrors collecting the backscattered light, by studying the variation of the overlap function with azimuth and elevation angle. Results from the last ten years of operation will be reviewed.

Speaker: Roberto Mussa (INFN Torino)

Lunch

Laser-based tools

4 First observations of the Atmospheric Lidar onboard of the EarthCARE satellite by the Pierre Auger Observatory

The Atmospheric Lidar (ATLID) onboard the Earth Cloud, Aerosol and Radiation Explorer (EarthCARE) has been repeatedly observed by the Fluorescence Detectors of the Pierre Auger Observatory. Side-scattered ultraviolet light from ATLID laser pulses is recorded by the Auger fluorescence telescopes, which are primarily designed to measure the longitudinal development of extensive air showers initiated by ultra-high-energy cosmic rays. These measurements enable a precise reconstruction of the atmospheric trajectory of the laser beam over the Observatory and provide a unique opportunity for systematic studies of the local atmospheric aerosol content. Furthermore, EarthCARE laser tracks can be observed at the Telescope Array Experiment in the USA within a few days during the same moon cycle, opening the possibility for a direct cross-calibration of the energy scales of the two cosmic-ray observatories. We present first reconstruction results from ATLID observations following EarthCARE’s launch in 2024. These results highlight the potential of satellite-based lidar observations to support calibration and atmospheric characterization efforts at the Pierre Auger Observatory.

Speaker: Thara Rubi Caba Pineda (KIT)

5 Raman Lidar Based Atmospheric Observations for High-Energy Astrophysics: the Pierre Auger Observatory and the Cherenkov Telescope Array Observatory.

Accurate, height-resolved atmospheric characterization is a critical requirement for the reconstruction of extensive air showers and Cherenkov light in ground-based high-energy astroparticle observatories. Raman lidar systems, based on Nd:YAG laser emitters and elastic plus inelastic (Raman) detection channels, provide direct measurements of vertical profiles of aerosol extinction and backscatter coefficients. This work reviews Raman lidar-based atmospheric observations developed for high-energy astrophysics, with particular reference to results reported for the Pierre Auger Observatory and the Cherenkov Telescope Array Observatory (CTAO). The systems operate typically at 355 nm, with nitrogen and water vapour Raman channels enabling independent retrieval of aerosol extinction coefficients, vertical aerosol optical depth, aerosol volume backscatter coefficient and lidar ratio, as well as, the water vapour mixing ratio profile.

At AUGER and CTAO, these measurements have been used to constrain and evaluate the aerosol-induced systematics on the energy estimation of astroparticles.

Speaker: Vincenzo Rizi (DSFC/UNIVAQ and INFN-LNGS)

6 Recent results from the Montpellier Raman Lidar

The Montpellier Raman Lidar is a prototype in its final form, designed and built to fulfil the requirements of CTAO. It will provide atmospheric profiles at 355, 387, 532, and 607 nm. It incorporate two distinctive design elements, a gated photomultiplier protocol to avoid excessive light coming from very low altitudes and an automatic alignement system. It is ment to be installed at the southern site of CTAO in Chile in 2028. We present latest results obtained after a 12 months periods of tests at the Observatoire de Haute Province, France. Extinction profiles has been calculated for both 355 nm and 532 nm to altitudes up to 10km and will be presented.

Speaker: Dr Georges Vasileiadis (CNRS/LUPM)

coffee berak

Laser-based tools

7 Aerosol Profiling with the Pathfinder Barcelona Raman LIDAR: Development of a data processing software suite for the Cherenkov Telescope Array Observatory

Accurate characterisation of the aerosol extinction profile is critical for ground-based gamma-ray observatories, where atmospheric transmittance directly affects the reconstruction of gamma-ray shower energies and the observatory's acceptance. The Cherenkov Telescope Array Observatory (CTAO) requires continuous aerosol profiling with range resolution better than a few hundred metres and aerosol optical depth (AOD) accuracy of ~0.03 RMSD.
To meet these requirements, the Barcelona Raman LIDAR (BRL) is being developed as the observatory's dedicated aerosol and cloud monitor. This contribution presents the performance of the pathfinder BRL (pBRL), a 1.8m class prototype operating at two elastic wavelengths (355 nm and 532 nm) and one Raman channel (387 nm on N₂).
A dedicated LIDAR Pre-Processing (LPP) software suite was developed, incorporating novel methods for robust background subtraction, likelihood-based analog-to-photon-counting signal gluing, adaptive rebinning, and automated cloud and planetary boundary layer detection and inversion. Test campaigns were conducted near Barcelona and at the Observatorio del Roque de los Muchachos during moonlit periods. Under these non-optimal conditions, the pBRL achieved a range resolution of ~50 m for strongly absorbing dust layers, and AOD retrieval accuracy of approximately 0.05.
These results demonstrate the instrument's capability to characterise AOD profiles across the troposphere, and form the basis for the final upgraded BRL for the CTAO-N.

Speaker: Markus Gaug (Universitat Autònoma de Barcelona and CERES-IEEC)

8 Characterisation of a Condenser Lens for High-Efficiency Light Collection with Photomultiplier Tubes

The Barcelona Raman LIDAR (BRL) system, which is being developed for the Cherenkov Telescope Array Observatory (CTAO) relies on photomultiplier tubes (PMTs) to detect weak optical signals backscattered by atmospheric molecules and aerosols. As aerosol transmission constitutes a major source of systematic uncertainty, efficient photon detection in the LIDAR receiver is essential to achieve the calibration accuracy and sensitivity required by CTAO.

We present an experimental study of the Hamamatsu PMT Module H11526 – a PMT coupled to a freeform-based condenser lens designed to enhance photon collection efficiency. Using a dedicated optical setup, a clear dependence of the detected signal on both the illumination position and the angle of incidence was revealed, highlighting non-uniformities in the effective collection efficiency. This work constitutes a first experimental assessment of freeform condenser lens optics for Raman LIDAR applications and demonstrates their potential to enhance photon collection in compact detector systems, such as BRL.

Speaker: Darko Kolar (Center for Astrophysics and Cosmology, University of Nova Gorica)

9 Monitoring of Vertical Aerosol Optical Depth (VAOD) for Astroparticle Experiments Using a Ceilometer

For astroparticle projects that utilize the Earth's atmosphere as a calorimeter for detecting cosmic rays, real-time knowledge of atmospheric conditions and optical properties is essential. The ceilometer, a commercial meteorological lidar typically used for measuring cloud base height, vertical visibility, and cloud cover, represents a robust tool for characterizing the aerosol content of the atmosphere.
Currently, a ceilometer is deployed at the Observatory of the Astronomical Institute of the Czech Academy of Sciences in Ondřejov, operating in close proximity to the SST-1M Cherenkov telescope. We present an analysis of long-term ceilometer data from this device, including the development of a modified algorithm for aerosol layer detection and the evaluation of Vertical Aerosol Optical Depth (VAOD).
The VAOD is derived using both the Klett–Fernald method and an inverse lidar approach, allowing for a direct comparison of these techniques in terms of stability, accuracy, and applicability to ceilometer data. The study also includes an assessment of the long-term atmospheric conditions at the Ondřejov site, providing insight into aerosol variability and overall air quality.
Additionally, atmospheric data from the Copernicus program are incorporated to complement ground-based measurements and to validate the obtained results. The primary objective is to provide high-precision atmospheric calibration data for the analysis of SST-1M telescope observations and to establish a methodological framework for future deployments, including the planned installation of an identical ceilometer at the Roque de los Muchachos Observatory (La Palma).
The proposed approach enhances the reliability of energy reconstruction and cross-calibration of ground-based gamma-ray detectors by enabling continuous, automated monitoring of atmospheric transparency.

Speaker: Vlastimil Jílek (Joint Laboratory of Optics)

10 Welcome Cocktail

Wednesday 29 July

Atmospheric Electricity

11 The Key Role of Extensive Air Showers with Particle Energies Above 10^15 eV in Lightning Initiation via Powerful Initial Breakdown Pulses (IBPs)

At present, it is impossible to explain the mechanism of lightning initiation in thunderclouds without considering the key role of powerful discharges that occur 0.04–3 ms after the lightning initiation. These discharges are termed Initial Breakdown Pulses (IBPs), and their peak currents are comparable to the high currents of lightning return strokes to the ground [Rakov & Uman, 2003].
In turn, it is impossible to explain such strong IBPs occurring within such a short timeframe (0.04–3 ms) without the initiating (triggering) role of secondary electrons, positrons, and photons from cosmic-ray Extensive Air Showers (EAS) with an initial particle energy above 10^15 eV [Kostinskiy et al., 2020a]. For effective lightning initiation, the flux of secondary electrons from an extensive air shower must increase exponentially within the strong electric fields of a thundercloud [Kostinskiy et al., 2020b].
Consequently, based on the analysis of the initial stages of lightning initiation and development, it can be stated with high probability that without extensive air showers, intracloud lightning and Narrow Bipolar Events (NBEs) would not occur at all.
Co-funded by the European Union (MERIT - Grant Agreement No.101081195).

Kostinskiy, A. Y., Marshall, T. C., & Stolzenburg, M. (2020a). The mechanism of the origin and development of lightning from initiating event to initial breakdown pulses (v.2). JGR:A, 125, e2020JD033191. https://doi.org/10.1029/2020JD033191
Kostinskiy, A.Y., Vlasov, A. and Fridman, M. (2020b). Calculation of the dynamics of the initiation of streamer flashes that provide the NBE VHF signal profile and the VHF phase wave propagation velocity. arXiv: 2005.12417 [v1] [physics.ao-ph] https://doi.org/10.48550/arXiv.2005.12417
Rakov, V. A., & Uman, M. A. (2003). Lightning: Physics and effects. Cambridge: Cambridge Univ. Press

Speaker: ALEXANDR KOSTINSKIY (Nuclear Physics Institute of the Czech Academy of Sciences)

12 CRIT-Cosmic Ray Ionization of Thunderstorms PHITS based model for a cloud electrification model

Cloud electrification models, such as CEM, developed at the Atmospheric Physics Institute of the CAS, take into account atmospheric ionization by cosmic rays. Originally, only fair weather conditions were considered. To expand this, we first tested CEM's response to changes in vertical ionization curves with a change of solar modulation potential and geomagnetic latitude using the CRAC:CRII model. Observing a positive response in local minima and maxima, absolute charge values, and discharge amounts led us to develop another model. Specifically, we modeled additional ionization caused by accelerated particles from cosmic ray air showers under strong thunderstorm electric fields, named Cosmic Ray Ionization of Thunderstorms (CRIT). This model was developed using the Monte Carlo transport code PHITS and subsequently simplified for use in CEM iterations.

Speaker: Jakub Šlegl (Nuclear Physics Institute of the CAS)

13 One Year of Measurements with THUNDERMILL02 Electric Field Mills at High-Altitude Observatories and Mobile Deployments

In 2025, the THUNDERMILL02 Electric Field Mill (EFM) instruments were deployed at two high-altitude mountain observatories: Basic Environmental Observatory Musala in Bulgaria (2925 m a.s.l.) and Observatory Lomnický štít, Slovakia (2634 m a.s.l.), complemented by mobile measurement campaigns in the Czech Republic. This contribution presents the first year of operational experience and selected scientific results from these deployments.

We report on the system performance of THUNDERMILL02 under demanding high-altitude conditions and show examples of thunderstorm electric field recordings captured at both observatories. Selected events are cross-correlated with simultaneous data from ionising radiation detectors co-located at the sites, allowing investigation of links between atmospheric electric fields and particle flux variations during thunderstorm activity. Where available, optical camera data provide additional context for selected events, offering visual insight into lightning development.

The three deployments, spanning different orographic and meteorological regimes, cover a wide range of measurement conditions for atmospheric electricity and ionising radiation studies. Unlike conventional electric field mills, THUNDERMILL02 captures both the quasi-static atmospheric electric field and rapid field changes, enabling more detailed multi-instrumental studies of atmospheric electricity and ionising radiation.

Speaker: Martin Kákona (Nuclear Physics Institute of the CAS)

coffee berak

Atmospheric Electricity

14 Recent observations of Transient Luminous Events above Central Argentina from the Pierre Auger Observatory

The Fluorescence Detector of the Pierre Auger Observatory, beyond its primary focus on cosmic rays, has proved to be a unique facility for the observation of ELVES and HALOS with unprecedented time resolution. Starting on December 2023, to complement these observations, we installed three cameras (TLEcams) to record a larger variety of TLEs with higher space resolution and longer integration times. This report will review the techniques developed to cross calibrate amplitude, space and time parameters of the events detected by our instruments, and the algorithms implemented to automatize the TLEcam data acquisition.

Speaker: Roberto Mussa (INFN Torino)

15 BOLT: Imaging Lightning and Terrestrial Gamma Flashes at the Pierre Auger Observatory

Lightning-related phenomena are known to interact with and influence all detector systems of the Pierre Auger Observatory. Notably, the Surface Detector has recorded unique signals associated with Terrestrial Gamma Flashes (TGFs) which are rare phenomena linked to the initial processes of lightning. Studying TGFs in coincidence with their parent lightning discharges helps to constrain the mechanisms responsible for their production, providing key insights into how these high-energy emissions are generated and evolve within thunderstorms.

To image the parent lightning discharges, we are developing the Broadband Observatory of Lightning and TGFs (BOLT), an interferometric lightning mapping array that enhances the unique capabilities of the Observatory by providing high-resolution 3D (spatial and temporal) imaging of lightning propagation. BOLT consists of radio detectors that have been previously developed for the Auger Engineering Radio Array and is co-located with the Surface Detector to enable direct correlation between lightning activity and candidate TGF signals at the Pierre Auger Observatory.

This contribution highlights recent hardware developments, progress towards selective triggering and precision timing, and first field data, illustrating the growing capability of the system for TGF and lightning studies. Together with the existing detector systems of the Pierre Auger Observatory, BOLT establishes a powerful experimental framework for advancing our understanding of lightning physics and associated high-energy atmospheric phenomena.

Speaker: Eric-Teunis de Boone (Center for Particle Physics Siegen, University of Siegen, Germany)

16 : The Atmospheric Science of Mini-EUSO space experiment: results and perspectives

Mini-EUSO is a telescope launched on board the International Space Station in 2019. Located in the Russian section of the station it has successfully performed so far more than 150 sessions with the aim of remotely sensing our planet from a nadir-facing UV-transparent window in the Zvezda module. The instrument is based on an optical system employing two Fresnel lenses and a focal surface composed of 36 Multi-Anode Photomultiplier tubes, 64 channels each, for a total of 2304 channels with single photon counting sensitivity and an overall field of view of 44$^\circ$. Mini-EUSO has multidisciplinary scientific objectives, among them the search for nuclearites and Strange Quark Matter, the study of atmospheric phenomena such as Transient Luminous Events, cloud distributions, meteors and meteoroids, the observation of sea bioluminescence. Mini-EUSO can map the night-time Earth in the near UV range (predominantly between 290 – 430 nm), with a spatial resolution of about 5.9 km and different temporal resolutions of 2.5 $\mu$s, 320 $\mu$s and 41 ms. Mini-EUSO observations are extremely important to better assess the potential of a space-based detector of Ultra-High Energy Cosmic Rays (UHECRs) such as POEMMA. In this contribution we describe the detector and present the various atmospheric phenomena observed in more than five years of operation and place them in the context of future space-based observatories of UHECRs, focusing on the perspective for remote sensing of the atmosphere and on the observation of lightning phenomena.

Speaker: Mario Edoardo Bertaina

Lunch

Other tools

17 All-sky infrared camera development for cloud monitoring

This project presents an all-sky cloud monitoring device based on a compact industrial infrared camera. A downward-facing camera observes a convex safety mirror coated with Al + SiO2, enabling thermal observation of the clouds. Such thermal observation, combined with ground-level temperature measurement, allows for cloud base height estimation.
This contribution will focus on introduction to the project design and assembly, outlining the underlying physical principles and discussing the project limitations and challenges.
At this stage the device is capable of observing clouds with sufficient contrast and resolution to estimate the position and base height. Current results indicate that the device could be suitable for use as a supporting tool for cosmic ray observation shifts.

Speaker: Petr Bořil (Palacky University Olomouc, Joint Laboratory of Optics, Czech republic)

18 Investigating variations seen in >20 years of atmospheric muon efficiency data from the H.E.S.S. Experiment

Muons created in extensive air showers in the lower atmosphere can leave ring-like traces in the images recorded by imaging atmospheric Cherenkov telescopes (IACTs). These traces can be used to monitor the optical throughput of an IACT via the so-called muon efficiency, a parameter calculated from the radius and brightness of these ring-like traces.
The standard calibration chain of the H.E.S.S. Experiment includes the calculation of the mean muon efficiency for each telescope and observation, yielding >20 years of detailed muon effieciency data. These time-series show the overall degradation of the optical efficiency due to hardware aging of the H.E.S.S. telescopes and also depict the sudden upward jumps as the mirrors or cameras underwent maintenance.
Besides these expected changes in muon efficiency, a residual variation on an annual scale can be observed which is so far not well understood.
This contribution presents a study that investigates these variations in detail, probing correlations to atmospheric as well as other observation conditions and outlines potential implications for IACT calibration procedures that rely on muon efficiencies.

Speaker: Doramas Jimeno Sanchez (Deutsches Elektronen-Synchrotron DESY)

19 Aerosol characterisation using wide field stellar photometry

The Angstrom coefficient characterises the wavelength dependence of aerosol extinction and allows the vertical aerosol optical depth (VAOD) measured in one waveband to be extrapolated to others. We determine the Angstrom coefficient using the FRAM (F/Photometric Robotic Atmospheric Monitor) telescopes — small robotic instruments designed for wide-field stellar photometry, currently deployed at sites of astroparticle physics observatories. VAOD is derived simultaneously in the Johnson B (440 nm), V (540 nm), and R (620 nm) filters. Shorter wavelengths are expected to yield higher VAOD. However, we observe a filter-dependent ordering VAOD(V) > VAOD(R) > VAOD(B) inconsistent with this expectation. We determine an intercept for each filter pair by fitting a linear relation between VAOD measured in one filter versus another — a relationship that would otherwise be expected to pass through the origin — and use it to correct the Angstrom coefficient calculation. We present results from FRAM and validate against independent AERONET sun-photometer measurements (2021–2022) at the Roque de los Muchachos. The B–V combination shows the best agreement with AERONET. The derived Angstrom coefficient distribution shows a bimodal structure: the low-α peak corresponds to Calima periods —
intrusions of Saharan dust dominated by large particles — while the
high-α peak reflects clean, non-dusty conditions.

Speaker: Mrs Shefali Negi (FZU - Insititute of Physics of the Czech Academy of Sciences)

coffee berak

Open discussion

20 Social Event

Thursday 30 July

Influence of atmosphere on measurements of present and future CR and Gamma-Ray esperiments

21 Air shower simulations in CORSIKA 8

Air shower simulations represent a critical component of data analysis in ground-based, high-energy astroparticle experiments, for which the Fortran-based CORSIKA 7 framework has been widely used. This contribution will present the development status and features of CORSIKA 8, a complete redesign of the simulation framework in the modern C++ language. Special focus will be placed on the modelling of the atmosphere in the framework.

Speaker: Radek Privara (Palacky University Olomouc)

22 Impact of Atmospheric Molecular Absorption and Realistic Cloud Conditions on CTAO-North Performance

The performance of Imaging Atmospheric Cherenkov Telescopes (IACTs), such as the Cherenkov Telescope Array Observatory (CTAO), depends critically on atmospheric conditions, which govern both air-shower development and Cherenkov light transmission. In this contribution, we focus on the latter. In the first part, we investigate seasonal and Stratosphere to Troposphere exchange-driven variations of absorbing molecules—primarily ozone—above the two CTAO sites. Using dedicated simulations, we assess the impact of these variations on image intensity, and trigger effective area, with particular emphasis on dynamic atmospheric phenomena such as stratosphere-to-troposphere transport events. In the second part, we study via simulations the effect of realistic cloud profiles, as observed over La Palma, on CTAO North performance. The results of these two studies provide quantitative estimates of the systematic uncertainties affecting CTAO performance and inform the development of its atmospheric calibration strategy.

Speaker: Georgios Voutsinas (University of Geneva)

23 Gamma-Ray Observations of the BBH Merger Candidate S241125n with MAGIC and LST-1 under Variable Atmospheric Conditions

We report on gamma-ray observations of the binary black hole (BBH) merger candidate S241125n, detected by the LIGO-Virgo-KAGRA Collaboration during the O4b observing run. Follow-up observations were performed with the MAGIC telescopes and the Large-Sized Telescope prototype (LST-1) of the Cherenkov Telescope Array Observatory. S241125n is of particular interest due to its temporal and spatial coincidence with a sub-threshold short-duration burst detected by Swift/BAT, Swift/XRT, and the Einstein Probe/FXT, offering a rare opportunity to probe potential electromagnetic counterparts to a BBH merger.

The observations were conducted under suboptimal atmospheric conditions, with the presence of cloud coverage significantly impacting data quality. To address this problem, LIDAR-based atmospheric measurements were included into dedicated Monte Carlo simulations of extensive air showers and Cherenkov light emission. Out of ~4 hours of LST-1 observations (including ~3.4 hours in joint configuration with the MAGIC telescopes), ~1 hour of data was retained, limited to selected runs where conditions allowed for reliable instrument response calibration. The spectral energy distribution and light curve were derived for reconstructed energies above 500 GeV. This approach ensures a reliable analysis despite adverse conditions and highlights the importance of real-time atmospheric monitoring for ground-based gamma-ray astronomy.

Speaker: Mario Pecimotika (Department of Polytechnics, Dr. Franjo Tuđman Defense and Security University, Zagreb, Croatia)

24 Impact of Calima on Atmospheric Transmission and the Performance of the CTAO LST System at ORM, La Palma

The next generation of imaging atmospheric Cherenkov telescopes, in particular the four LSTs (Large-Sized Telescopes) of the CTAO (Cherenkov Telescope Array Observatory), will provide substantially improved sensitivity compared to previous instruments. This increased sensitivity also makes precise atmospheric characterization more important, since even moderate atmospheric disturbances can affect the transmission of Cherenkov light and, consequently, the reconstruction of cosmic gamma rays. At the ORM (Roque de los Muchachos Observatory) on La Palma, besides clouds, one of the most relevant atmospheric disturbances is calima, i.e. Saharan dust intrusion.

In this work, we modeled plausible vertical distributions of calima above ORM and used the MODTRAN (MODerate resolution atmospheric TRANsmission) code to calculate wavelength-dependent atmospheric extinction profiles. Five dust-concentration levels at telescope altitude, from weak to strong calima, were considered, using values motivated by measurements from the TNG (Telescopio Nazionale Galileo) on La Palma. The resulting extinction tables were then used as input to air-shower and detector-response simulations with CORSIKA (COsmic Ray SImulations for KAscade) and sim_telarray in order to evaluate the impact of dust-induced atmospheric extinction on key performance parameters of the LST system.

The main goals of the study are to determine the dust-concentration limit at telescope level up to which observations remain scientifically useful, and to quantify the impact of calima on reconstructed shower and image parameters in order to support the development of an adequate correction method for dust-affected observations. The results are also relevant for atmospheric monitoring, data-quality assessment, and observing strategy for present and future Cherenkov-telescope experiments.

Speaker: Dario Hrupec (Department of Physics Josip Juraj Strossmayer University of Osijek)

coffee berak

25 Discussion and closing