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==> In this proposal, more time is being requested for KKAWARA.PQ
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ISO is the first telescape which has potential to detect dust emission from
many high-redshift quasars and to provide database for studies of evolution of
circumnuclear regions and host galaxies of quasars.  Once the quantity of dust
is established as a function of redshifts, our knowledge of evolution of
quasar host galaxies, especially in terms of star-formation history, will
greatly advance.  Such importance led many groups to dedicate massive
observing time to observe about 150 quasars in total from z = 0 up to z = 4.9.
The dust abundance in high-redshift quasars would result from formation through
supernova explosions and destruction by intense radiation from the central
source.  Hence, the luminosity of dust emission relative to the luminosity of
the central source should provide an interesting check on other measurements
related to star-foramation history of quasar host galaxies.  To achieve this
goal, we must know the dust abundance as a function of redshifts, or in other
words "spectral evolution in the infrared" has to be established.
However, statistics made by using "the Search tool for the Reserved Targets
Lists" shows that the quasars reserved for the existing GT (Guaranteed Time)
and OT (Open Time) programs are not well coordinated to form a sample
appropriate for this purpose.  The difference in the average absolute B-band
magnitude Mb for reserved quasars between 0 < z < 1 and 3 < z <5 quasars is
a factor of 50 (about 4 mag difference).  The real situation is even worse.
The reduction of in-flight sensitivities of the PHT far-infrared photometry
bands sets the detection limit to Mb = -29 for quasars at z > 3, thus making
the Mb difference even greater.  Suprisingly, there is only one quasar with
Mb < -29 at z <2.  Here, we are proposing to add new quasars to the reserved
quasars in such a way that this small addition makes the ISO quasar database
complete in terms of study of spectral evolution.