Astropy and Jupyter Notebooks

Overview

Teaching: 30 min
Exercises: 0 min

Questions

• What is Astropy?

Objectives

• Learn some basic functionality in Astropy

• Learn some basic functionality in Jupyter Notebooks.

In this episode we will cover the Astropy library. But first we will shift from the Terminal and text editor to Jupyter Notebooks to give you a taste of this coding environment and its functionalities.

Jupyter Notebook

In the Terminal, with your Astroconda environment loaded, type the following:

jupyter notebook

This command will open up a window in your browser.

In the top right corner of this window, use the New button to create a notebook. If more than one options are available in the dropdown menu, do select Python 3.

Do a little walk through the notebook here, types of cells, running cells, adding new ones, non-linear execution.

Imports work just the same:

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt

And so do shell commands:

ls data/*fits

data/J_A+A_523_A7_table10.fits      data/J_A+A_523_A7_table9.dat.fits
data/J_A+A_523_A7_table11.dat.fits  data/ib3747060_drz.fits*

Astropy

(Astropy)[https://www.astropy.org/]

The astropy librarby has very limited functionality, with more stuff available in the affiliated libraries.

Reading in a table:

from astropy.table import Table
tab = Table.read('data/J_A+A_523_A7_table10.fits')

Opening a fits image:

from astropy.io import fits
image = fits.open('data/ib3747060_drz.fits')

Displaying header:

print(data[0].header)

Displaying image:

plt.imshow(data[1], vmin=0.0, vmax=0.1)

Key Points

• To start up Jupyter Notebooks type jupyter notebook in your terminal.

• Know how to execute cells and navigate around the notebook.

• Understand the pitfalls of the non-linear execution of notebooks.

• Astropy has several basic sub-modules.

• A fits file can be read with astropy.io.fits.

• An image is just a numpy array that can be plotted with matplotlib.pyplot.imshow().