Tutorial & Examples

by Ian Boyle and Chuck Keeton

30 Aug 2005

by Ian Boyle and Chuck Keeton

30 Aug 2005

INTRODUCTION

This tutorial provides step by step instructions for four
basic lensing calculations as an introduction to the
gravlens
software as well as one section that covers additional commands.
Each example is presented in two parts: the analytical solution and the
solution as found using
gravlens.
This tutorial assumes familiarity with basic lens theory.
For quantitative examples, the following values are assumed:

G = 6.67 x 10

c = 3 x 10

M = 10

D

D

D

D

This tutorial progressively builds on the material presented so each section assumes an understanding of the material explained in the previous sections. The following index lists the gravlens material reviewed in each part of the tutorial:

SECTION
I. Point Mass Lens

- gridlo1 variable
- gridhi1 variable
- Interactive runs
- Input files
- Model and parameter definition
- ptmass
model

- Lens position parameters

- findimg command
- Relation between angular and Cartesian coordinate positions
- findimg
results

- alpha model
- Power law index parameter

- Cental "ghost" image

- Shear parameter
- Source position on origin

- Source position off origin

- findimg3 command
- findsrc command