SUMMARY OF PROPOSAL 41129 MR. HIDETOSHI KUBO UNIVERSITY OF TOKYO JAPAN 113 TOKYO 7-3-1 HONGO BUNKYO-KU E-mail: KUBO@ASTRO.ISAS.AC.JP Tel: 0427-51-3911(2612) Fax: 0427-59-4253 Medium: 2.5GB8MM Subject: AGN Title: ORIGIN OF THE VERY HARD SPECTRUM OF THE HIGH REDSHIFT QUASAR Q0636+680(Z Abstract: We propose to observe the high redshift quasar Q0636+680(z=3.2). This quasar has the hardest xray spectrum among the high redshift quasars observed with ROSAT. This was interpreted as being possibly due to excess absorption. ROSAT could not constrain the absorber and the continuum form, but ASCA observation can do so significantly. It is important to understand the origin of the hard spectrum because it must impose constrains on the nature of the xray emission and the physical environment. It may also give clue to the AGN evolution and the cosmic xray background. Co-Is: 1 TADAYUKI TAKAHASHI ISAS JAPAN TAKAHASI@ASTRO.ISAS.AC.JP 0427-51-3911(2622) 2 JYUN KATAOKA ISAS JAPAN 3 AKIKO YAMASHITA ISAS JAPAN 4 TUNEYOSHI KAMAE UNIV.OF TOKYO JAPAN 5 MAKOTO TASHIRO UNIV.OF TOKYO JAPAN 6 MASARU MATSUOKA RIKEN JAPAN 7 TAKAYA OHASHI TOKYO METRO. UNIV JAPAN 8 NORIKO YAMAZAKI TOKYO METRO. UNIV JAPAN Target Name PRI RA Dec Time TC Off GIS SIS_Cts Obs ------------------- --- -------- -------- ---- -- --- --- ------- --- Q0636+680 2 100.5179 67.9766 60 N N P 0.01000 1