Forgot to put the license in

COPYING.txt

@@ -0,0 +1,35 @@
+========================
+ pyXSIM licensing terms
+========================
+
+pyXSIM is licensed under the terms of the Modified BSD License (also known as New
+or Revised BSD), as follows:
+
+Copyright (c) 2016-, John ZuHone <[email protected]>
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification, 
+are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this list
+of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice, this list
+of conditions and the following disclaimer in the documentation and/or other materials 
+provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its contributors may be 
+used to endorse or promote products derived from this software without specific prior 
+written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY 
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 
+OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
+SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
+OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR 
+TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 
+EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+

doc/source/index.rst

@@ -52,6 +52,11 @@ link between the simulation data and the algorithm for generating the X-ray phot
 detailed information about the design of the algorithm in yt, check out
 `the SciPy 2014 Proceedings. <http://conference.scipy.org/proceedings/scipy2014/zuhone.html>`_
 
+License
+-------
+
+pyXSIM is released under a `BSD 3-clause license <https://opensource.org/licenses/BSD-3-Clause>`_.
+
 Table of Contents
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