Skybot3D

The Virtual Observatory
Solar System in 3D

Version: 3.0 2020-04-01

Presentation

Skybot3D is an extension of the SkyBoT service. It is composed of a Web service and a standalone software. It has been designed for whom wants to explore the Solar System in 3D, to learn the structure of the small solar system objects, and to visualize the various population classes of asteroids (NEAs, Main Belts, Trojans, Centaurs, KBOs), comets, planets and major natural satellites . It is also a usefull service to query and retrieve at once the heliocentric state vectors or spherical coordinates of all solar system objects or a subset of them.

The high accuracy ephemeris provided by Skybot3D makes it perfect for scientists who are interested to get quickly a snapshot of the solar system at a given epoch.

Skybot3D is also the ideal tool for whom wants to create realistic animations such as a Solar system tour or the encounter of a Near-Earth asteroid with the Earth. View demo...

API

The Skybot3D Web service allows to retrieve a dataset of positions of Solar System objects through several methods:
getAster
This method extracts the positions of asteroids from the Skybot database, for a reference epoch the closest from the requested epoch.
getComet
This method extracts the positions of comets from the Skybot database, for a reference epoch the closest from the requested epoch.
getPlanet
This method computes the positions of planets and their major satellites, for a reference epoch the closest from the requested epoch.
getSso
This method provides the positions of all the Solar System objects (asteroids, comets, planets and their major natural satellites) for a reference epoch the closest from the requested epoch.
Administrative method:
getAvailability
This method provides the availability of the Skybot3D Web-service. Check now!

Practical use

The Skybot3D service is a SaaS which allows to access methods to gather Solar System state vectors through SOAP requests or by using VO applications such as Aladin or Topcat. The underlying technology (XML+SOAP+WSDL) being inherently interoperable, you can use them and implement them regardless of what your favourite platform and operating system are. For that, you can freely download toolkits client to help you to make the integration of the Skybot3D service seamless with your code.

The easiest way to implement Skybot3D is to use a non-interactive network downloader (e.g. curl, wget) to send HTTP requests and to receive the result "on your desktop". Advanced users may prefer to query Skybot3D directly through its API.

Scientific issues

The ephemerides provided by Skybot3D are heliocentric equatorial mean J2000 coordinates, expressed in a rectangular (position and motion vector) or a spherical (right ascension, declination and distance) format in the ICRF. The position and motion vectors of asteroids and comets are computed by numerical integration of a two bodies problem perturbed by the 8 planets, taking into account relativistic perturbations (post-newtonian approximation). The source of the orbital elements of asteroids is the ASTORB database, and those of comets is the IMCCE cometary database. The ephemerides of the planets are computed using the planetary theory INPOP, and the major natural satellites are computed using dedicated solution of their motion: V. Lainey, V. Dehant and M. Pätzold 2007 for Mars, V. Lainey, L. Duriez and A. Vienne 2004 for Jupiter, A. Vienne and L. Duriez 1995 for Saturn, J. Laskar and R.A. Jacobson 1987 for Uranus, and C. Le Guyader 1993 for Neptune.

The ephemerides of the solar system objects, or a subset of them, can be retrieved in two manners:

  • by using the getAster or getComet or getPlanet synchronous methods. These methods require no computation (only requests to databases) and are rather fast. Each method allows to filter out the classes of objects in order to retrieve a subset of them.
  • by using the getSso synchronous method to get all the solar system objects (provided by the previous methods) in a single request, without filter out object classes.

The synchronous methods are freely available without restriction. The only limitation of these methods is that the positions of objects are given for a specified epoch T0 close to the requested epoch by less than few days (see next section).

To get the ephemerides of the solar system objects at a given epoch, you must use the previous methods in asynchronous mode. This is recommended only for advanced users who need accurate positions of all solar system objects for their work. See the asynchronous mode section for more information about this mode.

Technical issues

The computation of accurate ephemerides of all the known Solar System objects (more than 920,000 asteroids and 1,400 comets early 2020) at a given epoch requires a numerical integration of their orbits. Even with parallel programming, the computation take a while. That is why the synchronous methods of Skybot3D do not compute ephemerides. Instead, to respond as quickly as possible, we extract the pre-computed positions of the Solar System objects available in SkyBoT databases. The cut-off of Sso positions in SkyBoT being 10 days, the positions returned by the synchronous methods are the positions of the objects at a reference epoch (that of SkyBoT) close to, at most, 5 days of the requested epoch. The returned positions are of course accurate at the reference epoch.

With almost 1 million asteroids known in the Solar System, the amount of data sent back by Skybot3D methods is substantial. Encoded in XML (VOtable), the maximum volume of data to download is about ~215 Mbytes if uncompressed (-getFile=1) , and ~33 Mbytes if compressed with Bzip (-getFile=0). In TEXT format, it is ~57 Mbytes if uncompressed (-getFile=1), and ~18 Mbytes bzipped (-getFile=0). For ~1200 comets, the maximum volume of data to download is ~540 Kbytes if uncompressed (XML, -getFile=1), and ~70 Kbytes if bzipped, while in TEXT format it is ~180 Kbytes uncompressed and ~40 Kbytes if bzipped. For JSON format, the volume of data to download is ~100 Mbytes for asteroids, and ~225 Kbytes for comets.

For the method getSso, the volume of data to download is ~33 Mbytes for VOtable format if bzipped (-getFile=0), ~233 Mbytes if uncompressed (-getFile=1), and ~22 Mbytes for TEXT format (ZIP archive). If the JSON format is used, the volume of data to download is ~100 Mbytes.

As a consequence, we strongly recommend to not request the Skybot3D getAster and getSso methods through an Internet browser with the parameter getFile equal to 1 without filtering the classes or without limiting the number of objects. In addition to the huge amount of data to download, the browser might be overloaded to format and display the data (XML, JSON, and even the TEXT format).

Asynchronous mode

TBD

Skybot3D software

TBD

User support

Each response sent back by the Skybot3D service contains a ticket number. This 18 digits number (e.g. 166134206162181138) identifies each request and may be used to retrieve information on its processing. If you face with errors by using the Skybot3D service (it could occur that no relevant error message is returned), please report us the ticket number corresponding to the problem. It will help you to anderstand and solve it, and you will help us to improve the service.

The information regarding requests sent to Skybot3D is stored in a dedicated database. No personal information is stored, except the IP address provided by the client, which is employed to make statistics on the geographical localization of the Skybot3D users. The Skybot3D logs are never disseminated nor sent on request. You can access to the public logs by using the following URL:

https://ssp.imcce.fr/webservices/skybot3d/showLog.php?ticket=[ticket]&method=[method]

where:

ticket
Ticket number of the request
method
Keyword defining the service:
  • Skybot3d(getAster), Skybot3d(getComet),
  • Skybot3d(getPlanet), Skybot3d(getSso),
  • Skybot(getAvailability)

If you are confronted with a bug, or if you would like to request improvements or special needs, please use the IMCCE Mantis Bug Tracker (Quick access: use the Report issue button in the portal menubar).

Notes to user

The numerical precision of the Skybot3D ephemerides differ from one target to another, mainly depending on the accuracy of the orbital elements. As a consequence, you should not consider the accuracy of the computed positions as the number of digit which is provided. It is only a numerical accuracy that is given to avoid truncation error.

In any case, the IMCCE cannot be held for person in charge for a misuse or interpretation of the Skybot3D service and the data that are provided.

How to cite SkyBoT

If Skybot3D was helpful for your research work, the following acknowledgment would be appreciated: "This research has made use of IMCCE's Skybot3D VO tool". Skybot3D being based on SkyBoT service, you can also cite the following article 2006ASPC..351..367B.