{Copyright (C) 1997, 2019 by Han Kleijn, www.hnsky.org
 email: han.k.. at...hnsky.org

The ephemeride calculation for the planets, comets and numerical integration is based on source code which is
copyright (C) 1998 by Springer-Nature, Berlin Heidelberg and originates the code described in the book 
Astronomy on the Personal Computer, ISBN 3-540-63521-1 3rd edition 1998.  Authors Oliver Montenbruck and Thomas Pleger.
Reproduced with written permission of SNCSC (Springer-Nature) dated 2019-3-27 under the conditions specified in the letter below.
The units using this code are marked as such in the header.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

Springer Nature letter dated 2019-3-27:
*** Johannes Kleijn
*** Netherlands
*** 27/03/2019
*** Dear Mr Kleijn,
*** Re: Your permission request dated: 26 March 2019, your reference: Johannes Kleijn (�Licensee�), our reference: Springer Nature Customer Service Center GmbH (�SNCSC�)
***     acting as a commissionaire agent of Springer Nature Ltd (the PUBLISHER)
*** Request for permission to use: Software code from Astronomy on the Personal Computer, 978-3-540-63521-5, 3rd Edition, 1998 by Montenbruck, Oliver (�Licensed Material�)
*** to be published in the Astronomy Program HNSky http://www.hnsky.org/software.htm under a GPL3 License.
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