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 isos 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 (pht-05//pht-03//pht05 - pht-03 for p2 and pht-25//pht-22//pht-25 - pht-22 for c200). the total measurement time is 6.1 hours. history: 21/01/98\t\t\t\tuk, rjl\tinstantiation and delivery .tdt 23205 .ott 20805
Instrument
PHT03 , PHT05 , PHT22 , PHT25
Temporal Coverage
1998-02-11T10:33:06Z/1998-02-13T02:04:06Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
