Hipparcos Payload and Satellite Characteristics


     Telescope configuration                    All-reflective Schmidt
     Field of view                                    0.9 x 0.9 degrees
     Focal length                                     1400 mm
     Separation between fields                 58 degrees
     Diameter of primary mirror               290 mm
     Mirror surface accuracy                    Formula: 0/60 rms

Primary Detection System:

      Modulating grid                                 2688 slits
      Slit period                                        1.2 arcsec (8.2 micron)
      Detector                                           Image dissector tube
      Photocathode                                    S20
      Sensitive field of view                       38 arcsec diameter
      Spectral range                                  375-750 nm
      Sampling frequency                          1200 Hz

Star Mapper (Tycho) System:

      Modulating grid                                 4 slits perpendicular to scan
                                                             4 slits at ±45 degree inclination
      Detector                                           Photomultiplier tubes
      Photocathode                                    Bialkali
      Spectral range ('B')                           Formula: 1_eff=430 nm, Formula: 2=90 nm     
      Spectral range ('V')                           Formula: 3_eff=530 nm,Formula: 4 =100 nm 
      Sampling frequency                          600 Hz

Satellite Parameters:

       Launch mass                                    1140 kg
       Power requirements                          295 W
       Uplink data rate                                 2 kbit/s
       Downlink data rate                            24 kbit/s
       Spin axis inclination to Sun                43 degrees
       Spin rate                                           168.75 arcsec/s

Mission Parameters:

       Launch date                                       8 August 1989
       End of operations                              15 August 1993
       Intended satellite orbit                       Geostationary            
       Actual satelliet orbit                           Geostationary transfer
       Total scientific data                             > 1000 Gbits