#!/usr/bin/env python
# coding: utf-8

# # Preface
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# Photometry is the measurement of the amount of light from an image. There are, broadly speaking, two types of photometry. *Aperture photometry* measures the amount of light inside a region (the aperture) of fixed size. This is the kind of photometry done by photoelectric photometers. *PSF photometry* fits the image of an object like a star to the point spread function (PSF) of the camera. It is essential to doing photometry in crowded fields.
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# ### The notebooks in this part of the guide draw heavily from the excellent [photutils documentation](https://photutils.readthedocs.io/en/stable/)