Institut de Mécanique Céleste et de Calcul des Éphémérides (IMCCE) Solar System Services (astroquery.imcce/astroquery.solarsystem.imcce)

Overview

IMCCE provides a number of Solar System-related services, two of which are currently implemented here:

  • SkyBoT: search for and identify Solar System objects that are present in a given area of the sky at a given time

  • Miriade: ephemerides service

Use cases for both services are detailed below.

SkyBot - Solar System Body Identification Service

Miriade - Ephemeris Service

The Miriade service enable the query of Solar System object ephemerides. The most minimalistic get_ephemerides query looks like this:

>>> from astroquery.miriade import Miriade
>>> Miriade.get_ephemerides('Ceres')
<Table masked=True length=1>
 target        epoch                 RA        ...  DEC_rate   delta_rate
                 d                  deg        ... arcs / min    km / s
bytes20       float64             float64      ...  float64     float64
------- -------------------- ----------------- ... ---------- ------------
  Ceres    2458519.315165116 242.1874308333333 ...   -0.14926  -20.9668673

This query will return ephemerides for asteroid Ceres, for the current epoch, and for a geocentric location. The query output is formatted as a Table.

Ephemerides Queries

Miriade queries are highly customizable.

Epochs and Location

get_ephemerides is able to query a range of epochs starting at epoch epoch in steps of epoch_step for a total of epoch_nsteps. epoch has to be provided as a Time object, a float (interpreted as Julian Date), or a string (interpreted as iso date YYYY-MM-DD HH-MM-SS). Time steps epoch_step are provided as string that consist of a floating point number followed by a single character: d refers to days, h to hours, m to minutes, s to seconds; e.g., '1.23d' defines a time step of 1.23 days. epoch_nsteps defines the number of steps between the individual ephemerides. By default, epoch_nsteps = 1, which means that only a single epoch epoch will be queried.

Consider the following example, which queries ephemerides for asteroid Pallas over an entire year with a time step of 1 day:

>>> from astroquery.miriade import Miriade
>>> Miriade.get_ephemerides('Pallas', epoch='2019-01-01',
>>>                         epoch_step='1d', epoch_nsteps=365) 
<Table masked=True length=365>
 target        epoch                 RA         ...  DEC_rate   delta_rate
                 d                  deg         ... arcs / min    km / s
bytes20       float64             float64       ...  float64     float64
------- -------------------- ------------------ ... ---------- ------------
 Pallas            2458484.5  200.5865645833333 ...    0.15854  -19.3678422
 Pallas            2458485.5 200.92699458333328 ...    0.16727  -19.4137907
 Pallas            2458486.5 201.26416541666663 ...    0.17613  -19.4552649
 Pallas            2458487.5 201.59800958333332 ...    0.18511  -19.4921113
 Pallas            2458488.5  201.9284608333333 ...    0.19421  -19.5241972
 Pallas            2458489.5 202.25545124999996 ...    0.20344  -19.5514101
    ...                  ...                ... ...        ...          ...
 Pallas            2458843.5  261.1308308333333 ...   0.025007   -2.2916737
 Pallas            2458844.5  261.5084158333333 ...   0.029542   -2.5107013
 Pallas            2458845.5 261.88534958333327 ...   0.034077   -2.7290895
 Pallas            2458846.5        262.2616025 ...   0.038612   -2.9467393
 Pallas            2458847.5  262.6371470833333 ...   0.043144   -3.1635784
 Pallas            2458848.5         263.011955 ...   0.047672   -3.3795565

The observer location is defined through the location keyword, expecting a string containing the official IAU observatory code, a spacecraft name, or a set of coordinates (see the Miriade manual for details).

Coordinate Types

The Miriade system offers a range of different coordinate types - sets of coordinates and properties that can be queried. In agreement with the Miriade webform query, the coordinate type in get_ephemerides is defined through an integer value. For a full discussion of the different coordinate types we refer to this section of the Miriade website. The keyword coordtype controls which set of coordinates and properties are queried.

Here, we list the different coordinates and properties as returned by get_ephemerides for the different coordinate types available (the item numbers refer to the integer code to be provided to the keyword coordtype to use these sets) :

  1. Spherical coordinates (default):

Column Name

Definition

target

Target name (str)

epoch

Ephemerides epoch (JD, float)

RA

Target RA at ephtype (deg, float)

DEC

Target declination at ephtype (deg, float)

delta

Distance from observer (au, float)

delta_rate

Rate in observer distance (km/s, float)

V

Apparent visual magnitude (mag, float)

alpha

Solar phase angle (deg)

elong

Solar elongation angle (deg)

RAcosD_rate

Rate of motion in RA * cos(DEC) (arcsec/min, float)

DEC_rate

Rate of motion in DEC (arcsec/min, float)

  1. Rectangular coordinates:

Column Name

Definition

target

Target name (str)

epoch

Ephemerides epoch (JD, float)

delta

Distance from observer (au, float)

V

Apparent visual magnitude (mag, float)

alpha

Solar phase angle (deg)

elong

Solar elongation angle (deg)

x

X position state vector (au, float)

y

Y position state vector (au, float)

z

Z position state vector (au, float)

vx

X velocity state vector (au/d, float)

vy

Y velocity state vector (au/d, float)

vz

Z velocity state vector (au/d, float)

rv

Radial velocity (km/s, float)

heldist

Target heliocentric distance (au, float)

x_h

X heliocentric position vector (au, float)

y_h

Y heliocentric position vector (au, float)

z_h

Z heliocentric position vector (au, float)

vx_h

X heliocentric vel. vector (au/d, float)

vy_h

Y heliocentric vel. vector (au/d, float)

vz_h

Z heliocentric vel. vector (au/d, float)

  1. Local coordinates:

Column Name

Definition

target

Target name (str)

epoch

Ephemerides epoch (JD, float)

AZ

Target azimuth (deg, float)

EL

Target elevation (deg, float)

delta

Distance from observer (au, float)

V

Apparent visual magnitude (mag, float)

alpha

Solar phase angle (deg)

elong

Solar elongation angle (deg)

  1. Hour angle coordinates:

Column Name

Definition

target

Target name (str)

epoch

Ephemerides epoch (JD, float)

DEC

Target declination at ephtype (deg)

delta

Distance from observer (au, float)

V

Apparent visual magnitude (mag, float)

alpha

Solar phase angle (deg)

elong

Solar elongation angle (deg)

hourangle

Target hour angle (deg, float)

  1. dedicated to observations:

Column Name

Definition

target

Target name (str)

epoch

Ephemerides epoch (JD, float)

DEC

Target declination at ephtype (deg)

RAJ2000

Target RA at J2000 (deg, float)

DECJ2000

Target declination at J2000 (deg, float)

AZ

Target azimuth (deg, float)

EL

Target elevation (deg, float)

delta

Distance from observer (au, float)

delta_rate

Rate in observer distance (km/s, float)

V

Apparent visual magnitude (mag, float)

alpha

Solar phase angle (deg)

elong

Solar elongation angle (deg)

RAcosD_rate

Rate of motion in RA * cos(DEC) (arcsec/min, float)

DEC_rate

Rate of motion in DEC (arcsec/min, float)

heldist

Target heliocentric distance (au, float)

hourangle

Target hour angle (deg, float)

siderealtime

Local sidereal time (hr, float)

refraction

Atmospheric refraction (arcsec, float)

airmass

Target airmass (float)

posunc

Positional uncertainty (arcsec, float)

  1. dedicated to AO observations:

Column Name

Definition

target

Target name (str)

epoch

Ephemerides epoch (JD, float)

RAJ2000

Target RA at J2000 (deg, float)

DECJ2000

Target declination at J2000 (deg, float)

delta

Distance from observer (au, float)

delta_rate

Rate in observer distance (km/s, float)

V

Apparent visual magnitude (mag, float)

alpha

Solar phase angle (deg)

elong

Solar elongation angle (deg)

RAcosD_rate

Rate of motion in RA * cos(DEC) (arcsec/min, float)

DEC_rate

Rate of motion in DEC (arcsec/min, float)

heldist

Target heliocentric distance (au, float)

siderealtime

Local sidereal time (hr, float)

refraction

Atmospheric refraction (arcsec, float)

airmass

Target airmass (float)

posunc

Positional uncertainty (arcsec, float)

Other parameters

A range of additional parameters is available in get_ephemerides to modify the query results:

  • timescale: switch between UTC (default) and TT

  • planetary_theory: use planetary ephemerides other than INPOP

  • ephtype: switch between J2000 ephemerides (default) and other coordinates

  • refplane: switch from equatorial coordinates (default) to ecliptical coordinates

  • elements: switch to MPCORB ephemerides instead of ASTORB

  • radial_velocity: provides additional information on target’s radial velocity

Acknowledgements

This submodule makes use of IMCCE’s SkyBoT VO tool and the IMCCE Miriade service. Additional information on SkyBoT can be obtained from Berthier et al. 2006.

Please consider the following notes from IMCCE:

  • If SkyBoT was helpful for your research work, the following acknowledgment would be appreciated: “This research has made use of IMCCE’s SkyBoT VO tool”, or cite the following article 2006ASPC..351..367B.

  • If Miriade was helpful for your research work, the following acknowledgment would be appreciated: “This research has made use of IMCCE’s Miriade VO tool

The development of this submodule is funded through NASA PDART Grant No. 80NSSC18K0987 to the sbpy project.

Reference/API

astroquery.imcce Package

IMCCE

author

Michael Mommert (mommermiscience@gmail.com)

Classes

MiriadeClass()

A class for querying the IMCCE/Miriade service.

SkybotClass()

A class for querying the IMCCE SkyBoT service.

Conf

Configuration parameters for astroquery.imcce.