Replace Binder in README with Google Colab

README.md

@@ -1,61 +1,42 @@
 # Astropy Tutorials
 
 This repository contains tutorial IPython notebooks for the
-[Astropy](http://astropy.org) project. These are typically longer-form, more
+[Astropy](http://astropy.org) project. These are typically longer-form,
 narrative presentations of functionality in the [Astropy core
 package](https://github.com/astropy/astropy) and any [affiliated
-packages](http://www.astropy.org/affiliated/index.html). The tutorials are
-therefore different from the [Astropy core package
-documentation](http://docs.astropy.org), which presents a more structured and
-exhaustive view of the Astropy core package.
+packages](http://www.astropy.org/affiliated/index.html). The tutorials are different
+from the [Astropy core package documentation](http://docs.astropy.org), which presents a
+more structured and exhaustive view of the Astropy core package.
 
 
-## View the tutorials rendered as HTML pages
+## Viewing and running the tutorials
 
 To see the tutorials rendered as static web pages, see the [Learn Astropy
 website](https://learn.astropy.org).
 
-To execute the tutorials interactively, you can either clone this repository to
-your local machine or use Binder to run the tutorials remotely, as described
-below.
+To execute the tutorials interactively, either use Google Colab to run the tutorials
+remotely or clone this repository to your local machine:
 
+- Run the tutorials in your browser with Google Colab
 
-## Run the tutorials locally
+[![Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/astropy/astropy-tutorials)
 
-To run the tutorials locally, you should start by cloning this repository with
-`git` or downloading an archive of this repository from GitHub. You will need to
-have [Jupyter notebook](http://jupyter.org/) and IPython installed and will need
-to install the tutorial dependencies specified in `requirements.txt`:
+- Run the tutorials locally
 
-    python -m pip install -r requirements.txt
+Clone this repository with `git` or download an archive of the repository from
+GitHub. You will need to have [Jupyter notebook](http://jupyter.org/) and IPython
+installed. Then install the `requirements.txt` that are specified in the folder
+containing the specific `.ipynb` tutorial you wish to run. For example, to run the
+`FITS-cubes.ipynb` tutorial, first install:
 
-To check that your environment is set up to run the tutorials, you can use the
-Makefile provided in this repository with the custom `envcheck` command:
+    python -m pip install -r FITS-cubes/requirements.txt
 
-    make envcheck
 
-If this line fails, your environment is missing packages, and you should run the
-pip install line shown above.
-
-The notebook files themselves live in the `tutorials` directory of this
-repository, organized by the names of the tutorials. These can be opened with
-Jupyter notebook as with any other notebook files.
-
-
-## Run the tutorials on Binder
-
-You can also get started with a remote environment to run the tutorial notebooks
-in your browser using [Binder](http://mybinder.org)
-
-[![Binder](http://mybinder.org/badge.svg)](https://mybinder.org/v2/gh/astropy/astropy-tutorials/main?filepath=tutorials)
-
-
-Contributing tutorial material
-------------------------------
+## Contributing tutorial material
 
 We are always interested in incorporating new tutorials into Learn Astropy and
-the Astropy Tutorials series. We welcome tutorials covering astro-relevant topics and they do not
-necessarily need to use the Astropy package in order to be hosted or indexed here.
+the Astropy Tutorials series. We welcome tutorials covering astro-relevant topics; they
+do not need to use the Astropy package in order to be hosted or indexed here.
 If you have astronomy tutorials that you would like to contribute to this repository,
 or if you have a separate tutorial series that you would like indexed by the
 Learn Astropy website, please see the [Contributing