# ARTS built-in documentation server

## Workspace Method jacobianAddPointingZa

### Description

Adds sensor pointing zenith angle off-set jacobian.
Retrieval of deviations between nominal and actual zenith angle of
the sensor can be included by this method. The weighing functions
can be calculated in several ways:
- ``calcmode = "recalc"``:
Recalculation of pencil beam spectra,
shifted with ``dza`` from nominal values. A single-sided
perturbation is applied (towards higher zenith angles).
- ``calcmode = "interp"``:
Inter/extrapolation of existing pencil
beam spectra. For this option, allow some extra margins for
zenith angle grids, to avoid artifacts when extrapolating
the data (to shifted zenith angles). The average of a
negative and a positive shift is taken.
The interp option is recommended. It should in general be both
faster and more accurate (due to the double sided disturbance).
In addition, it is less sensitive to the choice of dza (as long
as a small value is applied).
The pointing off-set can be modelled to be time varying. The time
variation is then described by a polynomial (with standard base
functions). For example, a polynomial order of 0 means that the
off-set is constant in time. If the off-set is totally uncorrelated
between the spectra, set the order to -1.
The number of elements added to the state vector (x) is
* if poly_order < 0 : length of sensor_time
* otherwise : poly_order+1
In the first case, the order in x matches sensor_time. In the second
case, the coefficient for polynomial order 0 comes first etc.

**Authors: **Patrick Eriksson, Mattias Ekstrom

### Synopsis

### Variables