Questions tagged [jpl-horizons]
Questions relating to the JPL Horizons solar system data and ephemeris computation service
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Meeus on the Positions of the Satellites of Jupiter
Ex. 44.a of Meeus Astronomical Algorithm, Second Edition, provide the position of the Galileans on December 16 1992 at 0h UT (p.311/488).
Procedure 1:
For Io, in terms of the Jupiter's equatorial ...
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Different Earth-centered ICRF positions in GMAT and Skyfield/Spiceypy with DE421
I compared the Earth-centered positions from the Moon in the ICRF (i.e., in GCRF) using three different sources:
SpiceyPy (https://pypi.org/project/spiceypy/)
Skyfield (https://rhodesmill.org/...
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Distance between Sun and Earth using JPL horizons
Using the JPL Horizons app at https://ssd.jpl.nasa.gov/horizons/app.html#/ would someone help to calculate the distance between the Sun and the Earth say 1 May 2023 00:00 UT? I used the following for ...
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Using NASA Horizons with Celestrak Socrates's TLE CDMs?
Has anyone succeeded with getting a list of Collision Data Messages (CDMs) from nice sites like Celestrak in order to feed them into NASA Horizon's ephemeris computation service. These would include ...
user30059
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What are exactly each of the coefficients in Modified Difference Arrays?
I am looking into the different types of SPK kernels.
Type 1 are the so-called Modified Difference Arrays (MDA).
The linked document mentions that its reference 163 contains a description of the ...
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Are there any sources with high-confidence state vectors for GRAIL-A?
I have been experimenting with propagation of Moon-orbiting satellites. In particular, of GRAIL-A.
In order to obtain state vectors to use as starting points for my propagation, and to compare the ...
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Why does Earth's North Pole RA flip by ~180 deg around AD2000 relative to SSB? (JPL Horizons data)
Using JPL's Horizons API I see that the Earth's North Pole RA flipped by ~180 degrees quite suddenly around AD 2000. It was pretty stable around 180deg for at least 1000 years prior, and then remains ...
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Where to get data for axis of rotation of solar system bodies?
Where can I get data for the axis of rotation of the (major) bodies of the solar system?
For each solar system body, I want to get a unit vector of its axis of rotation (at a specified point in time).
...
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Why is there a 38.6 km Earth-Moon distance difference between Ephemeris types "Observer table" and "Vector table" on Horizons Web Application?
The image above is a screenshot from Horizons Web Application with the Ephemeris type: Observer Table.
It shows the distance (delta) from the geocentric observer location to target Moon on April 15, ...
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How to calculate earth's precession using JPL Horizons System?
I'm new to JPL Horizons and understanding how to use the tool efficiently.
I'm looking to extract earth's precession data and understand where we are in the current cycle. I understand we progress 1 ...
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How does JPL define the exact position of Lagrange points in the real solar system where (I thought that) they can't be defined?
My answer to Does the distance to L2 vary? is
The correct answer is "No, they are only mathematically defined when the orbit is circular".
but @DavidHammen's answer explains that they can ...
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What is the inertial heliocentric reference system used by NASA JPL to calculate the ephemerides of Near Earth Objects?
I'm using the website of NASA JPL Horizon system at this link Small-Body Database Query
to download a database of orbital elements for NEOs (asteroids and comets).
Although I checked the Horizons ...
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Positions of asteroids in heliocentric ecliptic (x,y,z) coordinates
I would like to make positions of asteroids in heliocentric ecliptic (x,y,z) coordinates plot for a given date, like in the image below (Matsuoka N. Ryo (CC-BY 4.0)).
For that I need so-called state ...
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How can I find the old reference orbit for JWST (from 2014) and get AltAz positions from Earth without learning Spice? Can Horizons do it? Can Python?
In this ancient 2017 answer to What happens to JWST after it runs out of propellant? I've plotted an eleven year long reference orbit for JWST that was available form Horizons at the time.
Now that ...
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Access to Chebyshev coefficients from JPL ephemerides
I want to generate an ephemeris file containing the Chebyshev coefficients, similar to how we can generate ephemeris file of positions with Horizon tool (https://ssd.jpl.nasa.gov/horizons/app.html#/). ...
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Is it posible to convert JPL Horizons Vectors to ECEF?
I'm needing to accurately find the sun and moon position in ECEF and I'm wanting to make use of JPL's Horisons VECTORS to do this.
What data should I export from the web interface and how should I ...
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Horizons ephemeris - how did they calculate that “Keplerian GM” value?
I’ve been playing with the NAIF’s SPICE library for some time (CSPICE in particular). In order to obtain the state vector of an asteroid from its osculating elements, I’m calling the “conics_c” ...
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Was the famous SPICE package of programs, utilities and data kernels named after "Melange" found on the planet Arrakis?
This question is NOT about a fictional planet:
This question is about NASA JPL history and the naming of SPICE. It is not primarily about the fictional planet Arrakis nor the fictional drug Melange ...
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Should coordinate transformations from J2000 to ITRF93 in quaternions be cyclic?
I used SPICE's pxform at an interval of epochs to determine the transformation from J2000 (inertial) to ITRF93 (Earth body-fixed) frame. Then, I converted these rotation matrices to quaternions with ...
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Why aren't there any trajectories for the Viking missions in JPL Horizons' database?
Horizons has calculated trajectories for deep space spacecraft, including six objects related to Apollo 8 through 12.
See an (old) list in the currently unanswered question What was Chang'e-2'...
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Why is the highest speed that Voyager 2 achieved from the Jupiter gravity assist not at perijove?
I plotted some data of the speed of Voyager 2 for various times (around the Jupiter flyby) and noticed that the highest speed that Voyager achieved was not at perijove and was wondering why this might ...
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Where are post-2017 EPIC images of Earth and the DSCOVR spacecraft coordinates available for download?
I tried to download orbital positions for the DSCOVR spacecraft in its Lissajous orbit around Sun-Earth L1 from JPL's Horizons web page but I was surprised to see the following!
No ephemeris for ...
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Why hasn't DSCOVR's trajectory determination been updated in JPL's Horizons after 2015-Aug-4?
I tried to download orbital positions for the DSCOVR spacecraft in its Lissajous orbit around Sun-Earth L1 from JPL's Horizons web page but I was surprised to see the following!
No ephemeris for ...
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Where can I find the specific details of a gravity assist space mission?
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I am writing a research essay where I need to know the specific details of a gravity assist mission such as Voyager 2's flyby of Jupiter for example (but any mission would work as long as it is a ...
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Possible idea for a simulation in orbital mechanics using data from the JPL [closed]
I have to write a research essay and have decided to write it on orbital mechanics where I would use data from the JPL to perform an experiment (simulation).
I was thinking of using the location data ...
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How to find instantaneous mass of a central body that results in a given osculating orbit?
This question was underspecified, so I'm going to try again.
Osculating orbital elements are Keplerian elements of a hypothetical orbit around a specified center which would be tangent to a specified ...
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JPL ephemerides: effect of Saturn, Uranus and Neptune
According to the Folkner ( Folkner et al, 2014, The Planetary and Lunar Ephemerides
DE430 and DE431, IPN Progress Report 42-196 • February 15, 2014), JPL ephemerides consider the following effects:
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What time is NASA using for Horizons web output?
Here's an example of some output from JPL's Horizons web interface.
NASA does not (appear to) specify which GMT is at those hours that the specific transits occurred, or at least I can't find it.
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Rotation matrix from J2000 to ITRF2008
I want to rotate a vector from the inertial J2000 frame into ITRF2008. I am using the NASA SPICE library, which provides a rotation matrix from J2000 to ITRF93 (they plan to upgrade the library to a ...
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How to find Horizons ephemerides or Spice kernels for the cis-lunar halo orbits of the Themis B & C) spacecraft?
The Themis spacecraft B and C have been renamed ARTEMIS P1 and P2 and moved around in cis-lunar space from Earth orbit to Lunar orbit.
This transfer involved libration point orbits, as discussed in ...
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Why are JPL using this expression to emulate Schwarzschild orbits?
From the documentation ”Formulation for Observed and Computed Values of Deep Space Network Data Types for Navigation ” expression 4-61 on page 4-42 it can be seen that JPL uses the following ...
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How to obtain Chebyshev coefficients directly from the JPL Horizon's interface?
I'm from Spain and I'm currently finishing my degree in Aerospace Engineering.
I am starting with all of this. My objective is to obtain the Chebyshev coefficients for the major planets position, ...
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Does JPL's Horizons have better MU69 state vectors for the New Horizons flyby somewhere?
Today I downloaded the state vectors for New Horizons and MU69 Arrokoth and subtracted their positions. The two new get closer than about 596,000 kilometers.
The New Horizons output header says:
<...
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NAIF and SpiceyPy returning seemingly inaccurate results
I am yet another amateur astrophysics enthusiast creating a solar system simulator. I began by hard-coding planetary bodies and their satellite orbiting characteristics via JPL data tables such as ...
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What's going on with NASA's Solar System Dynamics?
JPL's Horizons web interface generates the following orange announcement:
IMPORTANT: The SSD Announcement email list is now available. Major changes are coming in the near future, including possible ...
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Determining the spacecraft position vector with respect to ICRF frame for Venus flyby
For an interplanetary mission design to Saturn, I have considered doing multiple gravity assists starting with Venus. I am using the JPL Horizons ephemeris and ESA Lambert Solver.
I have the velocity ...
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Generating JPL HORIZONS parameters for use with JPL HORIZONS itself
I want to be able to calculate RA/Dec for a given body with JPL HORIZONS, using a heliocentric specification of the orbital elements for a small solar system body (say, Apophis), but instead of using ...
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How can I know if NASA Horizons output is measured, calculated, estimated or what-else?
This link allows downloading from NASA Horizons server data about the distance of a body (OSIRIS-REX spacecraft ) from the Sun (see link here):
How can I know how the distance is obtained?
Is it ...
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What happened to time in 1962? (JPL Horizons changes displayed time from UT1 to UTC for dates starting in 1962)
I was viewing some observer output from JPL's Horizons while writing this answer and I saw this annotation. "Prior to 1962, times are UT1. Dates thereafter are UTC".
Presumably users of JPL's ...
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How exactly to use astroquery.jplhorizons to get the state vectors of Mercury and the Parker Solar Probe?
In the question Is the Parker Solar Probe's semimajor axis being so close to that of Mercury's just coincidence? Does it help somehow? I used a Python script to plot the heliocentric orbit of the ...
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How is the Chebyshev method used by JPL?
In the DE packages, NASA gives us a series of coefficients for the Chebyshev approximation.
As I understand it, those approximations are given by a series of polynomials $T_n$ for the interval $[-1,1]$...
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How to show spacecraft position, heading etc relative to an asteroid
Given all the cool asteroid and comet missions out there (OSIRIS-REx, Hayabusa2, etc) I want to track the approach of the spacecraft to the asteroid.
My favorite tool, JPL Horizons, can provide highly ...
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Calculation of Sun-Satellite and Moon-Satellite distance
I have the coordinates of a satellite in the Earth Centered Inertial frame.
I have calculated the Sun-Earth and Moon-Earth vectors using the JPLEphemeris package.
Now I have to calculate the Sun-...
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Sources for SPICE Kernel (SPK) files for asteroids
Besides the official source for SPK files (ftp://ssd.jpl.nasa.gov/pub/eph ...) is there a place where people upload kernels for the smaller bodies in the solar system? I was looking for the Jupiter ...
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Difficulty trying to use the SPK file ast343de430.bsp
I'm looking for a NAIF SPK file (these typically end in .bsp) for a bunch of asteroids in the J2000 reference frame. I found ...
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I've almost learned to spell Chebyshev, why has JPL switched to Hermite interpolation for DE438?
According to @ChrisR's thorough answer
One caveat however is that the interpolation in DE438 is a Hermite interpolation, and no longer a Chebychev interpolation, so you may need to update your code....
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What are the problems that need to be taken in consideration when trying to find planetary position by using jpl ephemerides?
I'm currently trying to determine the position of the sun and the moon from jpl ephemeris DE200 which is referred to the dynamical equator and equinox of 2000 and uses tdb time. I am using the j2000 ...
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Will these equations give me the approximate apparent RA and Dec using positions from Horizons?
In this answer @DavidHammen showed me how to get coordinates from JPL's Horizons using the Earth's equatorial plane as a reference plane by selecting
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How does JPL calculate Epochs for generating ephemerides?
How exactly do epochs fit into the computational propogation of data of NASA's Jet Propulsion Laboratory and what methods do they use to calculate the properties of those epochs in the first place?
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