Solar system objects identification

The method skybotconesearch is intended to people who need to search for and identify Solar System objects (asteroids, planets, natural satellites and comets) that are present in a field of view of given celestial coordinates and radius at a given epoch.

HTTP Request

If you are a software/solutions developer, you might want to include the SkyBoT skybotconesearch service into your application. This can be done by using the web service method or by using the following HTTP request:[parameters]
where [parameters] is a list of parameters separated by the character &, which may be composed in two ways:
- standard Simple Cone Search (SCS) interface
the parameters are encoded in the URL with standard keywords providing a J2000 right ascension and declination (in degrees) and a search radius in degrees of the requested field of view in the sky. A non standard but mandatory keyword (EPOCH) must be added to specify at which epoch you are searching for solar system objects. These parameters are described in Table 1.
- non standard interface
the parameters are encoded in the URL with dedicated keywords providing the relevant information to search the solar system objects located in a given field of view. These parameters are described in Table 2.

If you choose to query SkyBoT using the SCS standard interface, you may also use the non standard keywords by adding them before the standard ones.

Table 1: Standard Simple Cone Search interface
EPOCH=<string> Requested epoch, expressed in Julian day or ISO dateTime - 2411320.0 .. 2473540.0
1889-11-13 12h .. 2060-03-21 12h
RA=<double> J2000 Right ascension of the FOV center degree 0° .. 360° (decimal)
DEC=<double> J2000 Declination of the FOV center degree -90° .. +90° (decimal)
SR=<double> Radius of the FOV degree 0 .. 30° (decimal)
VERB=<int> Level of output parameters (optional) - 1, 2, 3 which correspond, respectively, to output object, basic, all
Table 2: Non standard interface
-ep=<string> Requested epoch, expressed in Julian day or formatted as any English textual datetime - 2411320.0 .. 2473540.0
1889-11-13 12h .. 2060-03-21 12h
-ra=<double> Right ascension or ecliptic longitude of the FOV center degree 0° .. 360° (decimal)
-dec=<double> Declination or ecliptic latitude of the FOV center degree -90° .. +90° (decimal)

Radius of the FOV
Size of the FOV as Δα x Δδ

0 .. 36000 arcsec
0 .. 600 arcmin
0 .. 10 degrees

0 .. 72000 arcsec
0 .. 1200 arcmin
0 .. 20 degrees
-mime=<string> Mime type of the results - votable | html | text | json
-output=<string> Output parameters - object | basic | obs | all
-observer=<string> Observer's location code - Optional parameter,
default = 500 (geocenter)
-filter=<double> Filter to retrieve only objects with a position error lesser than the given value. 0 implies no filter arcsec Optional parameter,
default = 120 arcsec
-objFilter=<string> Code to indicate which objects must be sought in the FOV - Optional parameter, default = 111 (all objects)
-refsys=<string> Code to indicate the reference plane of coordinates - Optional parameter:
EQJ2000 (default) | ECJ2000
-from=<string> Word which definite the name of the caller application, or which describes the request - Any short string
(no space character)

The output results are described in the following section, and are available in VOTable (default), HTML, plain text format, and JSON object (cf. examples). Some arguments are optionnal and their values can be omitted. In that case, the default values are used.

Web service

The SkyBoT Web service provides methods based on SOAP and HTTP POST verb which allow one to interact between its own application and the SkyBoT service. Here is the useful information to invoke the SkyBoT skybotconesearch method:
Web Service URI:
SOAP header:
name of the SOAP header element: clientID
SOAP header's content: array('from' => 'YourName', 'hostip'=>'')
skybotconesearch (inputArray)
The input parameter of the method is an array which must contained the following parameter:
VariableTypeUnitsLimits or valuesDefaultComment
epoch string - 2411320.0 .. 2473540.0
1889-11-13 12h .. 2060-03-21 12h
none Requested epoch, expressed in Julian day, ISO format
or formatted as any English textual datetime
alpha double degree 0° .. 360° (decimal) none Right ascension or ecliptic longitude of the FOV center
delta double degree -90° .. +90° (decimal) none Declination or ecliptic latitude of the FOV center
radius string arcsec 0 .. 108000 arcsec
0 .. 216000 arcsec
none Radius (single value)
sizes (<value> x <value>) of the FOV
mime string - votable | html | text | json votable Mime type of the results
output string - object | basic | obs | all basic Output parameters
observer string - Code of observer's location 500 IAU observatory code or observer's location code
filter double arcsec 0 implies no filter 120 Filter on the error of position: only targets with position
error lesser that the given value are retrieved
objFilter string - 100 | 010 | 001 | 110 | 101 | 011 | 111 111 Code to indicate which objects must be sought in the FOV, respectively asteroids, planets and comets.
refsys string - EQJ2000 | ECJ2000 EQJ2000 Code to indicate the reference plane of coordinates

The output of the skybotconesearch method is an object containing the following attributes:

the status of the response: flag=1 means ok; flag=0 or flag=-1 mean that an error occured
the HTTP status-code of the response (e.g. 400: bad request, 422: Unprocessable Entity, 500: internal error)
the Unix timestamp of the response which can be useful to stamp the request
a string containing the ephemeris of the requested solar system body with the parameters described in the output results section
Depending on the selected mime type, the output is formatted as:
the data are written in the IVOA standard VOTable format
the data are transformed from VOTable to HTML by XSLT processing (SkyBoT XSL style sheet)
the data are returned in plain text where each value is separated by the pipe '|' character
the data are written in a JSON object.

Query examples

Output results

The output parameters of the method is a string which contains the following information:

1 Object number (blank if unnumbered) - x x x x
2 Object name (official or preliminary designation) - x x x x
3–4 Astrometric J2000 equatorial or ecliptic coordinates at the given epoch,
relatively to the observer, sexagesimal format
α in hour, δ in deg
long and lat in deg
x x x x
5 Class - x x x x
6 Visual magnitude mag x x x x
7 Error on the position arcsec x x x x
8–9 Motion on the celestial sphere (Δα'cos(δ), Δδ) or (Δlon cos(lat), Δlat) arcsec/h   x x x
10 Distance to observer au   x x x
11 Heliocentric distance au   x x x
12 Phase angle degree     x x
13 Solar elongation degree     x x
14–19 Mean J2000 heliocentric equatorial or ecliptic position and velocity vectors
at epoch T0
au and au/d       x
20 Reference epoch of the position vector Julien Day       x
The VOTable, whatever the output, contains three hidden fields dedicated to Aladin software: namely the astrometric J200 right ascension and declination (fields _raj2000 \ and _decj2000), andan external link to hint the targets (field externallink).

Structure of the output JSON object

When the output mime type is the JSON data-interchange format, the output of the skybotconesearch method is encapsulated into a structure defined as follows (case output=all):
    "Num": {int | string}, 
    "Name": {string}, 
    "RA (hour)": {string}, 
    "DEC (deg)": {string}, 
    "Class": {string},
    "VMag (mag)": {float}, 
    "Err (arcsec)": {float}, 
    "dRA (arcsec\/h)": {float}, 
    "dDEC (arcsec\/h)": {float}, 
    "dg (ua)": {float}, 
    "dh (ua)": {float}, 
    "Phase (deg)": {float}, 
    "SunElong (deg)": {float}, 
    "position (au)": { "x": {float}, "y": {float}, "z": {float} },
    "velocity (au\/d)": { "x": {float}, "y": {float}, "z": {float} },
    "ref_epoch": {float} 

How to consume

You have two ways to use the SkyBoT web service: by writting a client to send requests to the SkyBoT server and to receive and analyze the response, or by using a command line interface and a data transfert program such as curl or wget. For that, just execute one of the following commands in a console:
$> curl "<URL>"
$> wget "<URL>"
where <URL> is described in section HTTP request.

In order to help you to invoke the SkyBoT web service, we provide some clients written in differents languages. Here are some detailed explanations to write a client with PHP and SOAP which invokes the skybotconesearch method:

1/ Provide the input parameters which are mandatory for the service:

// Client's ID: provide the name of your project or organisation or yourself
$from = 'MyName';
// Input parameters
$param = array('epoch'     => 2453384.92153935181,
               'alpha'     => 148.67,
               'delta'     => 16.3838,
               'radius'    => "900",
               'mime'      => "votable",
               'output'    => "basic",
               'observer'  => "500",
               'filter'    => "120",
               'objFilter' => "111",
               'refsys'    => "EQJ2000");

2/ Define the SOAP options, the namespace and the WSDL URI of SkyBoT web service:

// Enables or disables the WSDL caching feature
ini_set('soap.wsdl_cache_enabled', 1);
// SkyBoT namespace
$namespace = '';
// SkyBoT WSDL
$uriwsdl = $namespace.'/skybot.wsdl';

3/ Create a SoapClient object in WSDL mode, set the SOAP header, then call the method and catch exceptions:

try {
   // Constructs the client
   $client = new SoapClient($uriwsdl, array('exceptions'=>1));
   // SOAP header
   $header = array('from'=>$from, 'hostip'=>'', 'lang'=>'en');
   $client->__setSoapHeaders(array(new SOAPHeader($namespace, 'clientID', $header)));  
   // Call the resolver method
   $response = $client->__soapCall(' skybotconesearch',$param);
   // Display the results
   if ($param['mime'] == 'text') {
      header("HTTP/1.0 200");
      header("Content-Type: text/plain");
      echo "# Flag: ".$response->flag.PHP_EOL;
      echo "# Ticket: ".$response->ticket.PHP_EOL;
      $res = explode(';', $response->result);
      $nbr = count($res);
      $newkey = array_keys($res);
      for ($i=0; $i<$nbr; $i++) { echo $res[$newkey[$i]].PHP_EOL; }
    } else if ($param['mime'] == 'json') {
      header("HTTP/1.0 200");
      header("Content-Type: application/json");
      echo $response->result;
   } else {
      header("HTTP/1.0 200");
      header("Content-Type: text/xml;content=x-votable");
      echo $response->result;
catch (SoapFault $fault) 
   trigger_error("SOAP Fault: {$fault->getTraceAsString()} (faultcode: {$fault->faultcode},
                               faultstring: {$fault->faultstring})", E_USER_ERROR);