50 lines
4.0 KiB
Markdown
50 lines
4.0 KiB
Markdown
---
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title: Testowy Artykuł - Tytuł
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description: Testowy artykuł - opis
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date: 2026-07-23
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category: news
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author: CTAO
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cover: /uploads/UAE_Event.jpg
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draft: true
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---
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_Artykuł testowy — treść skopiowana z newsa CTAO:_ [_Preparing the Montpellier Raman LIDAR Calibration System for CTAO-South_](https://www.ctao.org/news/preparing-the-montpellier-raman-lidar-calibration-system-for-ctao-south/)_._
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***
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**An essential part of the CTAO telescopes' detectors is situated well above their actual mechanical structure: the Earth's atmosphere.** It is there that high-energy gamma rays interact with atmospheric molecules, giving rise to a [cascade of particles that produce faint flashes of Cherenkov light](https://www.ctao.org/emission-to-discovery/science/how-ctao-works/). Because atmospheric conditions dictate how this light reaches the ground, it is fundamental to characterise our skies continuously — a task performed by devices known as **Raman LIDARs**.
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## How a Raman LIDAR works
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1. The instrument fires powerful laser pulses into the atmosphere — two beams of different wavelengths at once, covering the spectrum of Cherenkov light seen by the telescopes.
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2. A telescope collects the light that bounces back.
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3. By measuring the exact time it takes for this light to return, it calculates the amount of aerosols present at different altitudes.
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4. The backscattered signal is separated into four channels — one dedicated to _Raman-scattered_ light, produced when photons interact with atmospheric nitrogen and shift slightly in wavelength.
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This configuration provides scientists with highly detailed atmospheric profiles, allowing them to pinpoint various aerosols.
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[](https://www.ctao.org/news/italian-minister-of-university-and-research-visits-the-ctao-south-site-in-chile/)
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_Zdjęcie testowe — kliknięcie prowadzi do powiązanego newsa CTAO._
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## Two instruments, two sites
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| Instrument | Array site | Location |
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| --- | --- | --- |
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| [Barcelona Raman LIDAR (BRL)](https://www.ctao.org/news/pathfinder-barcelona-raman-lidar-completes-its-performance-evaluation-phase/) | CTAO-North | La Palma, Spain |
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| Montpellier Raman LIDAR (MRL) | CTAO-South | Atacama Desert, Chile |
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The MRL is being developed by researchers from the In-Kind Contribution (IKC) team at **LUPM** (Laboratoire Univers et Particules de Montpellier), France. It shares a similar foundational design with its northern counterpart — a large 1.8-metre mirror, a high-specification laser and a bespoke detection module — but what truly sets it apart is its in-house technology:
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- a specialised **timing protocol** for the light sensor, capturing atmospheric profiles at altitudes as low as **230 metres**;
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- an **automated alignment and calibration protocol** for the entire detection chain, reducing human intervention to a minimum — a tremendous advantage in the remote, high-altitude Chilean desert.
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## Validated against a European reference network
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Recently, the MRL team concluded a **24-month testing phase** at the Observatoire de Haute-Provence in France. Atmospheric profiles were recorded, analysed and validated against data from LATMOS, a reference site of the European Aerosol Research Lidar Network (EARLINET). The results confirmed that all individual elements of the LIDAR performed successfully.
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## Next step: the design review
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These evaluations propel the project toward the **Critical Design and Mechanical Review (CDMR)** — a comprehensive evaluation by the CTAO Central Organisation, verifying that the instrument's design is mature, safe and ready for final construction. In the near future, a panel of experts will visit France to officially initiate the review; passing it is mandatory for installation at CTAO-South.
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> An observatory requires many different pieces working in harmony. Beyond the telescopes, calibration and monitoring instruments like the MRL are necessary to guarantee the highest quality data.
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