Earth straylight measurements with PHT

the earth straylight program is performed with both the p2 detector at 25 micron, where the emission by the earth has a maximum, and the c200 detector at 170 micron, the channel which is most sensitive to any kind of straylight, as representative detector subsystems. the measurement is a differential one by comparing the absolutely calibrated surface brightness of a relatively dark background level at 3 different illumination angles of the inner side of iso.s sunshade by the earth. for stability monitoring of the detector conditions each time a dark and a measurement of a secondary sky standard are performed. in order to have similar constellations for both p2 and c200 the measurements are performed on two subsequent revolutions. revolutions 819 and 820 offer good constellations of earth, sun and moon. the observations are performed with aots (pht05//pht03//pht05 pht03 for p2 and pht25//pht22//pht25 pht22 for c200). the total measurement time is 6.1 hours. history: 21/01/98uk, rjlinstantiation and delivery .tdt 23205 .ott 20805 truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]