Radio Wave Detectors
VIRGO
The Variability of solar IRradiance and Gravity Oscillations (VIRGO) is an international collaboration of different European countries. This is a part of the payload of the SOHO spacecraft. SOHO is an international collaboration programme between ESA and NASA. The VIRGO experiment will provide the following observational and derived data: - continuous high-precision, high-stability and high-accuracy measurements of the solar total and spectral irradiance and spectral radiance variation; - continuous measurements of the solar polar and equatorial diameters; - frequencies, amplitudes and phases of oscillation modes in the frequency range of 1 uHz to 8 mHz; The total irradiance is measured with active cavity radiometers (PM06-V and the Dual Irradiance Absolute Radiometer, DIARAD), the spectral irradiance by three-channel Sunphotometers (SPM) and the radiance with 12 resolution elements on the solar disk using the Luminosity Oscillations Imager (LOI). These data will be utilized to achieve the main scientific objectives of VIRGO summarized in the following list: - detect and classify low-degree g modes of solar oscillations; - determine the sound speed, density stratification and rotation in the solar interior, specifically determine the physical and dynamical properties of the solar core; - study the solar atmosphere through comparison of amplitudes and phases of the p modes with these from GOLF (Global Oscillations at Low Frequencies) and SOI/MDI (Solar Oscillation Investigation/Michelson Doppler Imager); - search for the long periodicities or quasiperiodicities that have been found in other solar parameters; - utilize the solar `noise' signal to develop models for the global signature of stellar surface parameters; - determine properties of the solar asphericity and its variation in time; - study the relation between p-mode frequency changes and irradiance variations; - study the influence of solar active regions and other large-scale structures on total and spectral irradiance; - study the solar energy budget; - provide accurate total and spectral irradiance data for input in terrestrial climate modelling. Observations of the total solar irradiance will be a continuation of previous measurements from satellites, which have been performed by the radiometer HF of the Earth Radiation Budget experiment (ERB) on the NIMBUS-7 satellite from November 1978 until January 1993 (Hoyt et al 1992), by ACRIM~I on the Solar Maximum Mission satellite (SMM) from February 14, 1980 until June 1, 1989 (e.g. Willson and Hudson 1991), by ACRIM~II on the Upper Atmospheric Research Satellite (UARS) since October 1991 (Willson 1992) and by SOVA (Solar Variability) on the European Retrievable Carrier (EURECA) from August 1992 until May 1993 (Crommelynck et al 1993, Romero et al 1994). For more information, see: http://www.ias.u-psud.fr/virgo/virgomain.html Group: Instrument_Details Entry_ID: VIRGO Group: Instrument_Identification Instrument_Category: Solar/Space Observing Instruments Instrument_Class: Radio Wave Detectors Short_Name: VIRGO Long_Name: Variability of Solar Irradiance and Gravity Oscillations End_Group Group: Associated_Platforms Short_Name: SOHO End_Group Group: Spectral_Frequency_Information Wavelength_Keyword: Ultraviolet Number_Channels: 1 Spectral_Frequency_Coverage_Range: 335 nm End_Group Group: Spectral_Frequency_Information Wavelength_Keyword: Visible Number_Channels: 1 Spectral_Frequency_Coverage_Range: 550 nm End_Group Group: Spectral_Frequency_Information Wavelength_Keyword: Near Infrared Number_Channels: 1 Spectral_Frequency_Coverage_Range: 865 nm End_Group Online_Resource: http://www.ias.u-psud.fr/virgo/ Group: Instrument_Logistics Instrument_Start_Date: 1995-02-12 Instrument_Owner: Institut d'Astrophysique Spatiale, Framce End_Group End_Group