Early Access Versions of AstroGrav
Users of AstroGrav are entitled to download and use early access versions of AstroGrav when they are available. These give you the opportunity to try out and comment on new features before they are finalized and released to the general public, and your feedback can help identify bugs and influence the final form that new features take.
AstroGrav Software License Agreement
You must click on the button below to accept the AstroGrav Software License Agreement before downloading any early access versions of AstroGrav.
AstroGrav Early Access Download
When you have accepted the license agreement, you can click on one of the buttons below to download the AstroGrav installer.
Alternatively, if you already have a version of AstroGrav installed on Windows, you can click on the button below to download just the AstroGrav executable (AstroGrav_ea.exe), without the sample simulations and documentation. This must be placed in the same location as your currently installed executable in order for it to work correctly.
AstroGrav Early Access Versions
The following early access versions of AstroGrav 5.1 have been released.
- AstroGrav 5.1 Early Access 01
- AstroGrav 5.1 Early Access 02
- AstroGrav 5.1 Early Access 03
- AstroGrav 5.1 Early Access 04
- AstroGrav 5.1 Early Access 05
The documentation and tutorial have not yet been updated to cover the new features and changes. Please contact us if you require further information or advice.
AstroGrav 5.1 Early Access 01 was uploaded on 7th November 2023, and has the following improvements and bug fixes in addition to those in earlier versions.
- The Edit / Import Objects... command has been enhanced by adding the importing of Earth satellites from CelesTrak.
AstroGrav 5.1 Early Access 02 was uploaded on 10th November 2023, and has the following improvements and bug fixes in addition to those in earlier versions.
- A bug has been fixed that caused inaccuracies in the importing of Earth satellites using the Edit / Import Objects... command. This bug was caused by incorrectly using the J2000 reference frame, instead of the JNow reference frame.
- The twelve CelesTrak satellite web addresses have been added to the Small Body tab in the Edit / Preferences... command.
- On Windows, the list of recently used simulations has been moved from the bottom of the File menu to the new File / Open Recent menu.
AstroGrav 5.1 Early Access 03 was uploaded on 13th November 2023, and has the following improvements and bug fixes in addition to those in earlier versions.
- A bug has been fixed that prevented the CelesTrak Search option of the Edit / Import Objects... command from working on Windows.
- The CelesTrak Search option of the Edit / Import Objects... command has been enhanced to allow full designations (such as '2016-12A') as well as condensed designations (such as '16012A').
- The popup on a satellite table's Designation column has been enhanced to display the designation in full, instead of in the condensed form.
AstroGrav 5.1 Early Access 04 was uploaded on 22nd November 2023, and has the following improvements and bug fixes in addition to those in earlier versions.
- In the Edit / Import Objects... command, the eight Trojan asteroid categories have been replaced with the corresponding eight Co-orbital asteroid categories.
- The Trojan asteroid category has been added between the Hilda and Centaur categories. This is identical to the old Jupiter Trojan category.
- In the Edit / Add Family... command, the true longitude has been replaced with the much more useful mean longitude.
- The February Hydrids sample simulation has been updated so that the meteoroids have equally spaced mean longitudes, instead of equally spaced true longitudes.
The easiest way to study a co-orbital asteroid is to import it, use the evolver settings to set the time step to the orbital period of the associated planet, and then run the simulation either forward or backward. The associated planet will then appear stationary in a view window, making it easy to observe the relative motion of the asteroid.
When this is done, co-orbital asteroids fall into one of the following sub-categories, although it is possible for an individual asteroid to occasionally move from one sub-category to another.
- Trojan: The asteroid always stays on one side of the line joining the planet and the Sun.
- Horseshoe: The asteroid crosses the far side of the line joining the planet and the Sun, going part way round, reversing direction, going part way round, reversing direction, and so on.
- Transition: The asteroid goes round and round, occasionally reversing direction.
- Consistent: The asteroid goes round and round, always in the same direction.
If the associated planet is one of the giant planets, it's a good idea to first use the Tools / Calculate Orbits... command to ensure that orbits are being calculated relative to the barycenter of all inferior objects, and to use the Edit / Remove Objects... command to remove the inner solar system. Removing the inner solar system makes the simulation evolve much more quickly, which is important when evolving with time steps as long as the orbital periods of the giant planets.
AstroGrav 5.1 Early Access 05 was uploaded on 25th November 2023, and has the following improvements and bug fixes in addition to those in earlier versions.
- A bug has been fixed that caused a 69 second error in the positions of satellites that had been imported with the Edit / Import Objects... command. This error was the result of a mix-up between TDB and UTC.
- The CelesTrak Search option of the Edit / Import Objects... command has been modified to automatically refresh the satellite data if this has not already been done in the preceding 15 minutes.
- The CelesTrak Search option of the Edit / Import Objects... command has been modified to initially evolve to the present time if the simulation time is more than a day away from this.