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 asteroids for which you want to retrieve their
state vectors. 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). You can use
a comma-separated list of classes to get more than one class. The definition of classes is case-insensitive.
getFile 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.
In the context of Skybot3D, the choice of one or another database is not important to the extent that the returned ephemerides are heliocentric. The only impact is the time limit of the data, which can be obtained by using the status method of the SkyBoT API.
The different project code name are:
sbot2: main SkyBoT database dedicated to the Earth (geocentric)sbotRosetta: database dedicated to the Rosetta spacecraftsbotKepler: database dedicated to the Kepler spacecraftsbotEarthL2: database dedicated to the Sun-Earth L2 pointsbotTESS: database dedicated to the TESS spacecraft We recommend using the code name sbot2, which is the default value of the argument project.