11.1.3 Gain Factors

The S$_{\lambda}^{-1}$ function for the LWR camera was derived from observations obtained at a UVC voltage setting of -5.0 kV. Therefore all LWR observations that have been obtained at the reduced voltage setting of -4.5 kV have an absolute calibration gain correction factor of 1.37 applied by the processing system (Harris 1985) to compensate. A message to this effect is included in the processing history log. In the event that an observation for any camera has been obtained at non-standard settings of either the exposure gain (normally MAXIMUM) or the camera read gain (normally LOW), an additional absolute flux scaling factor is multiplicatively applied as follows (cf. Coleman et al., 1977):

• Exposure Gain Corrections

  Maximum:

  Correction = 1.0

  Medium:

  Correction = 3.0

  Minimum:

  Correction = 10.0

• Read Gain Corrections

  High:

  Correction = 0.33

  Low:

  Correction = 1.0

Corrections are also applied to the absolute flux spectrum to take into account changes in camera sensitivity as a function of time (observation date) and camera temperature (THDA). The derivation and application of these corrections are detailed in the following sections.