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Atmospheric Absorption

The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform

T Bretz – 1st expert on this subject based on the ideXlab platform

  • a method to correct iact data for Atmospheric Absorption due to the saharan air layer
    HIGH ENERGY GAMMA‐RAY ASTRONOMY: Proceedings of the 4th International Meeting on#N#High Energy Gamma‐Ray Astronomy, 2009
    Co-Authors: D Dorner, K Nilsson, T Bretz

    Abstract:

    Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma‐ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Therefore, a method to correct the data for the effect of the SAL is required. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma‐ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Therefore, a method to correct the data for the effect of the SAL is required. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.

  • a method to correct iact data for Atmospheric Absorption due to the saharan air layer
    Astronomy and Astrophysics, 2009
    Co-Authors: D Dorner, K Nilsson, T Bretz

    Abstract:

    Context. Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma-ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Aims. To correlate IACT data with other measurements, e.g. long-term monitoring or Multi-Wavelength (MWL) studies, an accurate flux determination is mandatory. Therefore, a method to correct the data for the effect of the SAL is required. Methods. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. Results. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.

D Dorner – 2nd expert on this subject based on the ideXlab platform

  • a method to correct iact data for Atmospheric Absorption due to the saharan air layer
    HIGH ENERGY GAMMA‐RAY ASTRONOMY: Proceedings of the 4th International Meeting on#N#High Energy Gamma‐Ray Astronomy, 2009
    Co-Authors: D Dorner, K Nilsson, T Bretz

    Abstract:

    Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma‐ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Therefore, a method to correct the data for the effect of the SAL is required. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma‐ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Therefore, a method to correct the data for the effect of the SAL is required. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.

  • a method to correct iact data for Atmospheric Absorption due to the saharan air layer
    Astronomy and Astrophysics, 2009
    Co-Authors: D Dorner, K Nilsson, T Bretz

    Abstract:

    Context. Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma-ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong Atmospheric Absorption affecting the data quality and resulting in a reduced gamma flux. Aims. To correlate IACT data with other measurements, e.g. long-term monitoring or Multi-Wavelength (MWL) studies, an accurate flux determination is mandatory. Therefore, a method to correct the data for the effect of the SAL is required. Methods. Three different measurements of the Atmospheric Absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. Results. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, were analyzed using the presented method, providing a corrected flux measurement for the study of the spectral energy distribution of the source.

Tang Lingli – 3rd expert on this subject based on the ideXlab platform

  • WHISPERS – A temperature and emissivity retrieval algorithm based on Atmospheric Absorption feature from hyperspectral thermal infrared data
    2016 8th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (WHISPERS), 2016
    Co-Authors: Chen Mengshuo, Qian Yonggang, Wang Ning, Ma Lingling, Li Chuanrong, Tang Lingli

    Abstract:

    Land surface temperature and emissivity separation (TES) is a key problem in thermal infrared (TIR) remote sensing. However, because of the ill-posed problem, the retrieval accuracy still needs to be improved. Through exploring the offset characteristics of Atmospheric downward radiance, a temperature and emissivity retrieval algorithm based on Atmospheric Absorption feature is proposed from hyperspectral thermal infrared data. Furthermore, an optimal channel selection is carried out to improve the efficiency and accuracy of method. The simulated results show that modeling errors less than 0.4K for temperature and 1.5% for relative emissivity for contrast materials and the accuracy is similar to the ISSTES method (Borel, 2008) for high emissivity materials. Furthermore, the proposed method can enhance the retrieval accuracy for low emissivity materials, that is approximately temperature 0.5 K and emissivity 2.1%.

  • A temperature and emissivity retrieval algorithm based on Atmospheric Absorption feature from hyperspectral thermal infrared data
    2016 8th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (WHISPERS), 2016
    Co-Authors: Chen Mengshuo, Qian Yonggang, Wang Ning, Ma Lingling, Li Chuanrong, Tang Lingli

    Abstract:

    Land surface temperature and emissivity separation (TES) is a key problem in thermal infrared (TIR) remote sensing. However, because of the ill-posed problem, the retrieval accuracy still needs to be improved. Through exploring the offset characteristics of Atmospheric downward radiance, a temperature and emissivity retrieval algorithm based on Atmospheric Absorption feature is proposed from hyperspectral thermal infrared data. Furthermore, an optimal channel selection is carried out to improve the efficiency and accuracy of method. The simulated results show that modeling errors less than 0.4K for temperature and 1.5% for relative emissivity for contrast materials and the accuracy is similar to the ISSTES method (Borel, 2008) for high emissivity materials. Furthermore, the proposed method can enhance the retrieval accuracy for low emissivity materials, that is approximately temperature 0.5 K and emissivity 2.1%.