Asteroids and Comets Tool

This tool allows you to display positions and  trajectories of asteroids and comets deduced from their orbital elements. To get information about one of the commands in this tool, left click on it in the image below:

The Auto import button allows you to download automatically from the Internet orbital elements of observable comets and certain classes of asteroids. It is the fastest way to update the orbital elements loaded in C2A and it is advisable to use this tool first. Clicking the button invokes the following dialogue box:

The orbital elements that you can import are as follows:

• Important comets which are potentially observable. The list of comets and their corresponding orbital elements are taken from the Website of the Minor Planet Center (MPC).
• Asteroids from the Lowell Observatory database maintained by Ted Bowell. You can specify whether to download 500, 1000, or 2000 primary orbital elements from a complete database containing 450000 objects characterised by their orbital elements (in a 115MB file). You can also download the complete Bowell catalogue, but the download time may be very long.
• A specific asteroids from the Astorb.dat Bowell file. The file can either be transfered automatically (in which case the transfer time can be very long) or be present in a folder on the local disk (the file location must be declared iith the Advanced Options command from the SolSys tab in the Options dialogue box). This file can be obtained from ftp://ftp.lowell.edu/pub/elgb/astorb.dat.gz.
• A list of asteroids identified by their names in the standard format of the MPC Ephemerides Designation. They must be provided in a text file with one name per line, and the access path to this file must be provided in the text area below the option. In order to get the orbital elements of the asteroids, the Astorb.dat file must be available on the local disk (the file location must be declared iith the Advanced Options command from the SolSys tab in the Options dialogue box). This file can be obtained from ftp://ftp.lowell.edu/pub/elgb/astorb.dat.gz.
• Bright asteroids at opposition for the year of the current map. The orbital elements are taken from the Website of the Minor Planet Center (MPC).
• Numbered asteroids in the MPC critical list.
• Near-earth asteroids or those with unusual orbits from MPC.
• Distant asteroids (Centaurians and Trans-Neptunians) from MPC.

By default, these are the observable comets from the Planet Center (MPC) along with 500 primary asteroids from the Bowell catalogue which are imported. Note that the dialogue box contains an option to overwrite all existing orbital elements. It is advisable to leave this option active, or successive imports will result in duplications appearing in the list of loaded objects. Indeed, C2A does not eliminate duplications when two objects of the same name are successively loaded (since you could use the different elements for the same object), except if you check the option Overwrite objects with the same name, in which case C2A check if an object with same name is already loaded and delete it if it is the case (take care that this possibility can considerably slow the import process down in case there is a large number of objects to import).

It is also advisable to select a single source for asteroids. Indeed, a given asteroid may be present in several sources, so it could then appear several times in the list managed by C2A.

You must of course be connected to the Internet to achieve automatic import of orbital elements. Once the import has been completed, you must close the window using the Close button.

The section How to display asteroids and comets explains step by step how to display positions and trajectories derived from orbital elements. The section How to declare orbital elements in a file provides the syntax to use in order to declare orbital elements for asteroids and comets in a text file.

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