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   PR # 41278
   Gravitational-lensing objects for roughly half of about 30
   gravitationally lensed QSO samples have already been confirmed by
   optical observations. However, lens objects for the other half
   samples have not yet been found despite of optical deep searches for
   them. These are called "dark lenses". We are planning to search for
   lens objects by X-ray detection of hot gases associated with deep
   gravitational potentials of dark lens objects. Encouraged by the
   first successful result, MG2016 (ASCA AO2), we propose X-ray search
   for the dark lens of the most misterious dark lens candidate
   Q2345+007.
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