NIMBUS I HRIR 



324 R/O 328 



SEPT. 19, \96i 



EAST OF PHILIPPINES 





SPACE 

 HOUSING A EARTH RADIATION 



IN FLIGHT CALIBRATION 

 HOUSING SURFACE 



:^ r.ryf^ 



Uw 



Figure 9 Portion of on HRIR analog record - Nimbus 1 



Only a small section of the record represents terrestrial radiation. As the scan 

 mirror rotates, it also measures the temperature of space and of the radiometer housing. 

 In the example shown, the mirror made two complete revolutions and thus gave two "scans" 

 or sweeps of the earth below the satellite. The distinctive "kick" of the space trace 

 formed a convenient reference point in positioning the satellite, while the characteristic 

 trace of the radiometer housing was useful in calibrating the temperature readout. 



(LaViolette and Chabot 1968b) 



18 



