getAster is a service of the IMCCE's Virtual Observatory project allowing to
retrieve the heliocentric J2000 state vectors of asteroids at a reference epoch.
The service can be used as a Web service and easily integrated into your own software (cf.
Skybot3D.getAster API). We propose some examples
of client programs for that. This page describes how to do with some of
the input parameters of the service.
getAster method
in your own software (see client templates) or call the HTTP request
on the command line interface using non-interactive file transfert programs such as wget or curl (see the
how to consume section).
getAster in the Location entry of the
File → Load Table menu of Topcat software.
epoch is used to define the epoch for which the heliocentric J200 state vectors are
requested. As the goal of the service is to provide the whole population of asteroids (almost one million object),
or a subset of them selected by their population class, the computation of their positions at a given epoch will
take a while. Thus, to ensure a relatively quick response, the service extract the data from the database of pre-computed
ephemerides of the SkyBoT service. Thus, the epoch provided by
the user is rounded at the closest epoch of the cut-off of the SkyBoT database, which is 10 days. This means
that the state vectors will be provided at an epoch close by 5 days to the requested epoch. In most cases
this is enough to study the Solar System as a whole.
The epoch must be formatted as an ISO 8601 date (recommended) or as a julian day or as a textual english date (in accordance with the GNU syntax of dates).
Examples of valid dates:
The epoch must be expressed in the UTC timescale. The period of time covered by SkyBoT is given by the status method.
Restriction: the shortcut 'now' can be used only in the HTTP request, not when calling the Web service.
Tolerance: the character 'T' of the ISO 8601 format can be omitted.
class to filter-out the SSOs in the various method of Skybot3D.
Fo asteroids and comets, you can omit the subclass term to get all the objects of a given class.
For example, class=NEA will allow to retrieve all the NEAs (Atira, Aten, Apollo and Amor).
For planets and satellites, you can get the former or the later by defening class=Planet
or class=Satellite.
500 for an observer located at the centre of mass of
the Earth (geocenter). If the place of observation is not referenced in the database of IAU observatories, then provide
the geographical coordinates formatted as a geographic location URI:
[+-]latitude, [+-]longitude, altitude[+-]longitude [+-]latitude altitudeThe longitude and latitude must be expressed in decimal degrees in the WGS84 reference system,
and the altitude must be expressed in meters above the mean sea level. Longitudes are negative toward
West. The sign + of the longitude and latitude can be omitted. If not, use the encoding
%2B instead of the symbol + which is not correctly transmitted in the URL.
Example for Paris observatory (2°20′11.4874" E, 48°50′11.32" N, 67 m):
-observer=007
-observer=%2B48.836477778, 2.336524278, 67.0— For an extra-terrestrial observer or an observer onboard a spacecraft, use one of the following codes recognized by SkyBoT:
earth@L2 | 500@L2 | @L2 | L2 for an observer located at the libration point L2 of the system Sun-(Earth+Moon)@rosetta | @-226 for an observer onboard the Rosetta spacecraft@kepler | @-227 | c55 for an observer onboard the Kepler spacecraft@tess | c57 for an observer onboard the TESS spacecraftgetFile argument?getFile argument is available only in the HTTP request. It allows the user to get back
the data directly instead of the actual response of the service that provides a link to download the data.
This easy solution must be used carefully, in particular if a request is submitted through a Web browser
without limiting the number of asteroids to retrieve: in some cases, the huge volume of data may freeze the
browser. Thus it is recommended to use the argument getFile=1 in test or development modes only.