### Header Variables

The most important header parameters are defined by default as SIC variables in a protected mode. The others, of less frequent use, can be accessed if required by the user (see “Advanced Processing”). The default variables are (RW means Read-Write variable, RO, Read-Only).

          TELESCOPE       Character*12, RW, Telescope name
          NUMBER          Integer,      RW, Observation number
          VERSION         Integer,      RO, Version number
          DATATYPE        Integer,      RO, Type of observation
                                            0 Line, 1 Continuum, 2 Skydip
          QUALITY         Integer,      RO, Quality of data
          SCAN            Integer,      RO, Original scan number
          UTOBS           Double,       RO, UT of observation (Radians)
          LSTOBS          Double,       RO, LST of observation (Radians)
          AZIMUTH         Real,         RW, Azimuth of observation (Radians)
          ELEVATION       Real,         RW, Elevation of observation (Radians)
          TSYS            Real,         RW, System temperature
          TIME            Real,         RW, Integration time (Seconds)

          SOURCE          Character*12, RW, Source name
          LAMBDA          Double,       RW, Longitude of source (Radians)
          BETA            Double,       RW, Latitude of source (Radians)
          OFF_LAMBDA      Double,       RW, Offset in longitude (Radians)
          OFF_BETA        Double,       RW, Offset in latitude (Radians)
          EQUINOX         Real,         RW, Equinox of coordinates (Years)

          LINE            Character*12  RW, Line name
          CHANNELS        Integer,      RO, Number of channels
          REFERENCE       Real,         RW, Reference channel
          FREQ_STEP       Real,         RW, Frequency step by channel (MHz)
          VELO_STEP       Real,         RW, Velocity step by channel (km/s)
          VELOCITY        Real,         RW, Velocity of reference channel
          FREQUENCY       Double,       RW, Rest frequency at reference channel
          IMAGE           Double,       RW, Image frequency "   "   "   "

          BEAM_EFF        Real,         RW, Telescope beam efficiency
          FORWARD_EFF     Real,         RW, Telescope forward efficiency
          GAIN_IMAGE      Real,         RW, Image to signal band ratio
          WATER           Real,         RO, Water vapor content (mm)
          PRESSURE        Real,         RO, External pressure (hPa)
          AMBIENT_T       Real,         RO, External temperature (K)
          CHOPPER_T       Real,         RO, Chopper temperature (K)
          COLD_T          Real,         RO, Cold load temperature (K)
          TAU_SIGNAL      Real,         RO, Opacity in signal band
          TAU_IMAGE       Real,         RO, Opacity in image band
          ATM_SIGNAL      Real,         RO, Atmospheric temperature
                                            in signal band
          ATM_IMAGE       Real,         RO, Atmospheric temperature
                                            in image band

          RX              Real[8192]    RO, X values of data points
          RY              Real[8192]    RW, Y values of data points

8192 is currently the maximum size of the spectra, but the variables RX and RY are redimensioned to the effective number of channels for each spectrum.