(quickstart)=

# Quickstart

Although it started as a simple program, `PyORBIT` got increasingly complex with time.
Before you start delving into the many available models, let’s work together on a few test cases to better understand the philosophy behind `PyORBIT`. 

- In [Radial velocity fit](radial_velocity_fit) we will fit radial velocity measurements of HD189733 
- In [Light curve fit](lightcurve_fit) we will fit light curves of HD189733 from several instruments
- In [Combined fit](combined_fit) we will fit radial velocities and light curves simultaneously

My suggestion is to follow the examples in the given order for a better understanding of the many functionalities of `PyORBIT`. 

```{toctree}
:maxdepth: 1
quickstart/radial_velocity_fit
quickstart/lightcurve_fit
quickstart/combined_fit
```