Astronomical Observatories

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Sean C Casey - One of the best experts on this subject based on the ideXlab platform.

  • the sofia program astronomers return to the stratosphere
    Proceedings of SPIE, 2006
    Co-Authors: Sean C Casey
    Abstract:

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) is the next generation of airborne Astronomical Observatories. Funded by the U.S. and German space agencies, SOFIA is scheduled for science flights beginning in late-2008. The observatory consists of a 747-SP modified to accommodate a 2.7-meter telescope with an open port design. Academic and government laboratories spanning both the U.S. and Germany are developing science instruments for SOFIA. Using state-of-the-art technologies, SOFIA will explore the emission of Astronomical sources with an unprecedented level of angular resolution (θ[arc-seconds] = 0.1 x wavelength [μm]) and spectral line sensitivity at infrared and sub-millimeter wavelengths. The current status of SOFIA is available from the observatory web site at http://sofia.arc.nasa.gov/ and is updated frequently.

  • the sofia program astronomers return to the stratosphere
    Advances in Space Research, 2004
    Co-Authors: Sean C Casey
    Abstract:

    Abstract The Stratospheric Observatory for Infrared Astronomy (SOFIA) is the next generation of airborne Astronomical Observatories. Funded by the US and German space agencies, SOFIA is scheduled for science flights beginning in late 2005. The observatory consists of a 747-SP modified to accommodate a 2.7-m telescope with an open port design. Academic and government laboratories spanning both the US and Germany are developing science instruments for SOFIA. Using state-of-the-art technologies, SOFIA will explore the emission of Astronomical sources with an unprecedented level of angular resolution ( θ [arc-sec]=0.1 × wavelength [μm]) and spectral line sensitivity at infrared and sub-millimeter wavelengths. The current status of SOFIA is available from the observatory web site at http://sofia.arc.nasa.gov and is updated frequently.

William L Bradford - One of the best experts on this subject based on the ideXlab platform.

  • improved upper winds models for several Astronomical Observatories
    Optics Express, 2011
    Co-Authors: Lewis C Roberts, William L Bradford
    Abstract:

    An understanding of wind speed and direction as a function of height are critical to the proper modeling of atmospheric turbulence. We have used radiosonde data from launch sites near significant Astronomical Observatories and created mean profiles of wind speed and direction and have also computed Richardson number profiles. Using data from the last 30 years, we extend the 1977 Greenwood wind profile to include parameters that show seasonal variations and differences in location. The added information from our models is useful for the design of adaptive optics systems and other imaging systems. Our analysis of the Richardson number suggests that persistent turbulent layers may be inferred when low values are present in our long term averaged data. Knowledge of the presence of these layers may help with planning for adaptive optics and laser communications.

  • improved models of upper level wind for several Astronomical Observatories
    arXiv: Instrumentation and Methods for Astrophysics, 2010
    Co-Authors: Lewis C Roberts, William L Bradford
    Abstract:

    An understanding of wind speed and direction as a function of height are critical to the proper modeling of atmospheric turbulence. We have used radiosonde data from launch sites near significant Astronomical Observatories and created mean profiles of wind speed and direction and have also computed Richardson number profiles. Using data from the last 30 years, we extend the 1977 Greenwood wind profile to include parameters that show seasonal variations and differences in location. The added information from our models is useful for the design of adaptive optics systems and other imaging systems. Our analysis of the Richardson number suggests that persistent turbulent layers may be inferred when low values are present in our long term averaged data. Knowledge of the presence of these layers may help with planning for adaptive optics and laser communications.

Lewis C Roberts - One of the best experts on this subject based on the ideXlab platform.

  • improved upper winds models for several Astronomical Observatories
    Optics Express, 2011
    Co-Authors: Lewis C Roberts, William L Bradford
    Abstract:

    An understanding of wind speed and direction as a function of height are critical to the proper modeling of atmospheric turbulence. We have used radiosonde data from launch sites near significant Astronomical Observatories and created mean profiles of wind speed and direction and have also computed Richardson number profiles. Using data from the last 30 years, we extend the 1977 Greenwood wind profile to include parameters that show seasonal variations and differences in location. The added information from our models is useful for the design of adaptive optics systems and other imaging systems. Our analysis of the Richardson number suggests that persistent turbulent layers may be inferred when low values are present in our long term averaged data. Knowledge of the presence of these layers may help with planning for adaptive optics and laser communications.

  • improved models of upper level wind for several Astronomical Observatories
    arXiv: Instrumentation and Methods for Astrophysics, 2010
    Co-Authors: Lewis C Roberts, William L Bradford
    Abstract:

    An understanding of wind speed and direction as a function of height are critical to the proper modeling of atmospheric turbulence. We have used radiosonde data from launch sites near significant Astronomical Observatories and created mean profiles of wind speed and direction and have also computed Richardson number profiles. Using data from the last 30 years, we extend the 1977 Greenwood wind profile to include parameters that show seasonal variations and differences in location. The added information from our models is useful for the design of adaptive optics systems and other imaging systems. Our analysis of the Richardson number suggests that persistent turbulent layers may be inferred when low values are present in our long term averaged data. Knowledge of the presence of these layers may help with planning for adaptive optics and laser communications.

K. Prabhu - One of the best experts on this subject based on the ideXlab platform.

  • Astronomical site survey report on dust measurement, wind profile, optical turbulence, and their correlation with seeing over IAO-Hanle
    Experimental Astronomy, 2017
    Co-Authors: Shantikumar S. Ningombam, S. Kathiravan, P. S. Parihar, E. J. L. Larson, Sharika Mohanan, Dorje Angchuk, Sonam Jorphel, K. E. Rangarajan, K. Prabhu
    Abstract:

    The present work discusses Astronomical site survey reports on dust content, vertical distribution of atmospheric turbulence, precipitable water vapor (PWV), surface and upper-air data, and their effects on seeing over the Indian Astronomical Observatory (IAO) Hanle. Using Laser Particulate Counter, ambient dust measurements at various sizes (0.3 μ m to 25 μ m) were performed at various locations at the site during November 2015. Estimated volume concentration for the particle size at 0.5 μ m was around 10,000 per cubic foot, which is equivalent to ten thousand class of clean room standard protocol. During the measurement, surface wind speed varied from 0-20 m s ^−1, while estimated aerosol optical depth (AOD) using Sky radiometer (Prede) varied from 0.02-0.04 at 500 nm, which indicates the site is fairly clean. The two independent measurements of dust content and aerosol concentrations at the site agreed well. The turbulence or wind gust at the site was studied with wind profiles at three different heights above the ground. The strength of the wind gust varies with time and altitude. Nocturnal temperature across seasons varied with a moderate at summer (6−8 ^∘C) and lower in winter (4−5 ^∘C). However, the contrast between the two is significantly small due to cold and extremely dry typical climatic conditions of the site. The present study also examined the effects of surface and upper-air data along with Planetary Boundary Layer (PBL) dynamics with seeing measurement over the site. Further, a comparative study of such observed parameters was conducted with other high altitude Astronomical Observatories across the globe.

Enzo Sauma - One of the best experts on this subject based on the ideXlab platform.

  • Economic impacts of installing solar power plants in northern Chile
    Renewable and Sustainable Energy Reviews, 2013
    Co-Authors: Felipe Del Sol, Enzo Sauma
    Abstract:

    Chile has one of the best worldwide conditions for the generation of electrical energy from solar resources, having an annual average Direct Normal Irradiation (DNI) of 9-10 kWh/m2/day. Many important Astronomical Observatories have been installed in the north of Chile because of the low number of cloudy days and the high sky clearness index. Also, in the north of Chile, there are many mining companies who demand large amounts of load for their operation. They currently use electricity provided from fossil fuels thermoelectric plants (99% of the electrical generation of the Northern Interconnected Power System is thermoelectric) that are subject to fuel-price volatilities and have large global and local impacts on the environment. The work reported in this paper focuses on identifying a limited number of variables, which explain the variations on the investment cost of solar power plants, and use this information to assess the economic benefits of the installation of this type of plants in the north of Chile. In particular, multiple linear regressions were formulated, with information about 45 thermal and 37 photovoltaic existing and projected solar plants, to explain the variations among the investment cost of the different projects. We determine a limited number of variables that adequately explain the variations of the investment cost of solar energy power plants. Using these results, 11 technologies were simulated in four locations to assess the economic impact of these projects in terms of the change induced in the marginal cost of the system and the net present value of the 44 projects. We show that installing a solar power plant in the north of Chile will not bring net economic benefits for the power sector unless current conditions on factors such as carbon bond prices, labor rate, or solar-plant part prices change. The break even capital cost and energy cost for a Stirling Dish solar plant in Calama are 2.33 millions of USD/MW and 9.3 cents/kWh, respectively. © 2012 Elsevier Ltd.