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   71123
   We propose to observe BL Lac object PKS0548-322 with ASCA and a TeV
   gamma-ray telescope. This source is classified as High frequency BL Lac
   objects (HBLs) whose emission could extend up to TeV gamma-ray band.
   Since TeV photon from extragalactic objects is absorbed by the cosmic
   infrared background (CIB) and the density of CIB is unknown, we can not
   know the cutoff of TeV spectrum of HBLs is intrinsic or due to
   absorption by CIB. There is a plausible argument that the TeV emission
   of HBLs is Synchrotron-Self-Compton emission by electrons radiating X-
   ray emission. In order to know intrinsic energy spectrum of electrons,
   simultaneous observations both in the X-ray and TeV gamma-ray band is
   crucial. These observations may also give clue to the cosmic gamma-ray
   background as well as CIB.
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