MESSIER is an application which simulates the formation of globular star clusters. Vary the number of stars and watch how clustering patterns remarkably similar to true astronomical objects evolve over time.

This program has been originally developed using Borland Delphi 2.0/3.0 for Windows '95 and later ported to Free Pascal 3.0/Lazarus 2.0 for Windows 10 and Ubuntu Linux; it is based on a BASIC version that appeared in the "Astronomical Computing" section of the Sky & Telescope Magazine, April 1986, p. 398.

To install, unzip the distribution file MESSIER.ZIP, using an output directory of your choice (e.g. c:\messier).

To start the program, double-click the file Messier.exe from Windows Explorer or Messier from your Linux distro file browser. Choose the "Run" option from the main menu to execute a simulation.

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.

• Version 1.00, 05/05/1998 - Initial release.
• Version 1.01, 11/05/1998 - Added color cycling to plot and number of stars plotted in cluster to the main window caption. More comments included to the program code.
• Version 1.02, 09/06/1998 - Fixed a bug that caused the program's description in the "About" dialog box to be partly chopped off at different screen resolutions.
• Version 1.03, 28/06/1998 - Added support to the orange color when plotting stars, with a call to the RGB Windows API function.
• Version 1.04, 18/07/1998 - Added a call to the ProcessMessages method of the application's main window to yield for other events when plotting a large number of stars. Added a call to the globular cluster plotting procedure to the OnPaint and the OnResize events. Beautified.
• Version 1.05, 16/08/1998 - Fixed a bug that prevented the clearing of the main window's display area when no stars was selected for plotting. Recompiled in Delphi 3.0.
• Version 2.00: 28/10/2019 - Converted to FreePascal 3.0.4/Lazarus 2.0.2.
• Version 1.06: 02/06/2023 - Recompiled in Delphi 7.0.