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Uhuru was the first satellite launched specifically for the purpose of X-ray astronomy. It was also known as the X-ray Explorer Satellite, SAS-A (for "Small Astronomy Satellite" A, being first of the three-spacecraft SAS series), SAS 1, or Explorer 42. The observatory was launched on December 12, 1970 into an initial orbit of about 560 km apogee, 520 km perigee, 3 degrees inclination, with a period of 96 minutes. The mission ended in March 1973. Uhuru was a scanning mission, with a spin period of ~12 minutes. It performed the first comprehensive survey of the entire sky for X-ray sources, with a sensitivity of about 0.001 times the intensity of the Crab nebula. ==Objectives== The main objectives of the mission were:〔( HEASARC "The Uhuru Satellite" )〕 * To survey the sky for cosmic X-ray sources in the 2–20 keV range to a limiting sensitivity of 1.5 × 10−18 joule/(cm2-sec), 5 × 10−4 the flux from the Crab Nebula * To determine discrete source locations with a precision of a few square minutes of arc for strong sources and a few tenths of a square degree at the sensitivity limit * To study the structure of extended sources or complex regions with a resolution of about 30 arc minutes * To determine gross spectral features and variability of X-ray sources * To perform, wherever possible, coordinated and/or simultaneous observations of X-ray objects with other observers. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Uhuru (satellite)」の詳細全文を読む スポンサード リンク
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