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   71116
   PKS 1830-211 is a Blazar gravitationally lensed by a foreground galaxy
   at z=0.89 (and possibly by another galaxy at z=0.19). Since only one of
   the two lensed images of the AGN is obscured by a thick (N_H ~ 5e22)
   interstellar matter of the lensing galaxy, we can separate the two
   images from temporal variations. The following scientific results are
   expected. (1) Constrains on the metal abundance of interstellar matter,
   which further constrains the star formation activities at z=0.89. (2)
   The magnification ratio of two lensed images which constrains the lens
   model. (3) Time variations of two images, in particular, the time delay
   between the two images. (4) Redshift of the Blazar if it has an iron
   emission line of EW=30eV. (5) Constraints on the Hubble constant from
   the above results.
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