=======
Physics
=======

The calibration engine implements the standard heterodyne calibration
equation, converting raw detector counts into antenna temperature
:math:`T_A^*` corrected for atmospheric absorption. This section
derives each component of the equation and maps it to its implementation.

.. toctree::
   :maxdepth: 2

   rayleigh-jeans
   calibration-loads
   atmosphere
   observation-modes
   calibration-equation

Symbol Reference
----------------

.. list-table::
   :header-rows: 1
   :widths: 15 40 25 20

   * - Symbol
     - Meaning
     - Unit
     - Typical range
   * - :math:`T_A^*`
     - Antenna temperature (atmosphere-corrected)
     - K
     - −1 to 100
   * - :math:`\gamma`
     - Gain calibration factor (counts → K)
     - K/count
     - 10⁻⁴ to 10⁻²
   * - :math:`T_{rec}`
     - Receiver noise temperature (SSB)
     - K
     - 100 to 5000
   * - :math:`T_{sys}`
     - System temperature
     - K
     - 200 to 10000
   * - :math:`\tau_0`
     - Zenith optical depth
     - Np
     - 0.01 to 5
   * - :math:`t_r`
     - Atmospheric transmission
     - —
     - 0.01 to 0.99
   * - PWV
     - Precipitable water vapour
     - mm
     - 0.01 to 10
   * - :math:`f_{eff}`
     - Forward efficiency
     - —
     - 0.95 to 0.99
   * - :math:`g_s x_s`
     - Signal sideband gain × suppression
     - —
     - 0.5
   * - :math:`g_i x_i`
     - Image sideband gain × suppression
     - —
     - 0.5