NEODyS provides information and services for all near-Earth asteroids (NEAs). Each NEA has its own dynamically generated home page providing information and services. A search facility puts the information in easy reach.

Starting from 1 September 2011 NEODyS is sponsored by ESA, which pays a portion of the operating costs, both for the background orbit and risk computations and for the database and web interface. The rest of the work is provided, as before, by the Department of Mathematics, University of Pisa, and by IASF-INAF (Rome), with the work of staff, including some retired.

The ESA participation is through a contract with SpaceDyS srl, a company of Cascina (Pisa, Italy), which is a startup promoted by the same research group which has built and operated NEODyS for the past 19 years.

The University and Research groups will in the near future continue to share the work and the responsibility, and are in any case committed to continue for a long period of time to contribute with research, innovation and certification functions.

This is the new version NEODyS-2, implementing the new error model based upon Farnocchia, Chesley, Chambelain and Tholen (Icarus 2015). The orbits have all been recomputed by using star catalog debiasing and an error model with assumed astrometric errors RMS deduced from the tests of the paper cited above. Risk files have bene recomputed for all PHAs, scanning for possible impacts for 100 years in the future; as a result, many objects do not have anymore a risk file, because the orbit has improved. A few NEAs have a risk file in NEODYS-2, while they had none in the old versions, but this is in most cases due to the increase of the final time of the scan from 2080 (which had been in use previoulsy) to 2118.

The software used for this version of NEODyS is OrbFit version 5.0.5; the free distribution can be obtained on request, but needs to be used by users which do understand the new error model. We have not yet implemented the correlation model for the astrometric errors, see Baer et al. (Icarus, in press 2011); a compensating increase of the RMS has been used as a safety margin. We plan to complete this additional step towards a fully consistent statistical error model soon (but no fixed date yet).

The NEODyS service is in some circumstances time critical (e.g., during special observation campaigns for asteroids at risk of being lost and/or with Virtual Impactors). At the moment we cannot provide a duplicate service to guarantee against network failures.

We are doing an effort to provide NEODyS with online help and captions. However, it is obviously not possible to explain all the technicalities involved in such a complex information system. The Tumbling Stone site had been created precisely to provide more user friendly information, including an illustrated dictionary of technical terms, and comments on the most relevant events and discoveries about Near Earth Asteroids. Unfortunately this site is not currently maintained.

The same services for other asteroids, including all numbered and multiopposition orbit objects, can be accessed at AstDyS.

How does it work?

These important buttons and links are at the top and bottom of every page:

Objects

To browse the list of objects in the NEODyS database.

Observatories

To browse the list of observing stations. (You can get a listing of the NEA observations and residuals for any station.)

Search

To search for a specific object or for objects with particular characteristics.

Risk page

Details known possibilities of Earth-asteroid collision. We operate the impact risk monitoring system CLOMON2, providing an estimate of the urgency of the problem based upon the Palermo Technical scale .

NEA elements

Catalogs of all NEA orbital elements in OrbFit format, updated daily.

Related sites

Links to related WWW sites.

Info & Credits

Information page: about Neodys, frequently asked questions, MJD conversion tables and other infos.

[Help]

Help window.

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This is the Tools icon (on the right in the top banner). Clicking repeatedly on it shows the following tools: Go to nea, Current date-time, MJD-calendar conversor and, finally, color and font-size selectors. When all the tools are displayed the icon changes to  ▼ . Clicking on  ▼  hides the tools and sets the icon again to  ▲ .

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Expands the main content area, hiding the banners and menus, to increase the available on-screen surface for data browsing. The same icon lets you restore the initial layout.

Contact »

Send feedback to the NEODyS team.

What's new?

• The NEODyS information system has recently changed its web interface. This was necessary to allow upgrade and maintenance of the web interface, because the previous version used propietary software which we could not maintain and which used obsolete libraries. The new interface will gradually diverge, that is acquire new functionality. We would appreciate receiving comments on the new interface.

Other features

• We are operating the impact monitoring service CLOMON2. The risk pages have a new format and contain more information, including the Palermo Technical scale for each possible impact.
• We are providing a link to the animated orbit diagrams available from JPL (e.g., Apophis).
• We are providing proper elements, computed by means of singular averaging, and encounter conditions; a figure shows the secular evolution of the proper elements (e.g., Apophis).
• We compute not only the Minimum Orbital Intersection Distance (MOID), but also all the stationary points of the distance function between the orbit of the asteroid and the orbit of the Earth; a figure illustrates the geometry of the distance function; this is informative especially in the cases with multiple minima (e.g., Apophis).
• We include the daily ephemeris for each object to the database. This allows an observer to search for all NEODyS objects that are visible now, or are in a certain region of sky, in particular taking into account the galactic disk. See the Search section to give it a try.
• Radar observations now incorporated into our orbital solutions. For those objects with radar observations, this results in substantially improved orbits, with far less uncertainty.
• We are now using simpler and constant URL's. This means that you can put a link to your favorite asteroid (e.g., Apophis) or to your favorite observatory (e.g., Highland Road Park Observatory) on your own web pages. You can also use bookmarks now, the URL for an object does not change.

What's next?

• We are working on the problem of assigning formal uncertainties, based upon the covariance matrix formalism, to all the quantities presented in the NEODyS home page of an asteroid. E.g., the perihelion distance, the MOID, the period, etc., should have a stated uncertainty.

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