Questions tagged [ephemeris]
Questions about the predicted positions of an object in space, like another planet, comet, or asteroid.
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Implementing the VSOP-2000 Ephemeris
For a project I'm doing, I need to implement the VSOP-2000 ephemeris for the Moon. However, unlike VSOP-87, there is little to no documentation online on how to use the data. For example, here is the ...
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How accurate should sun\moon ephemeris be for calculating eclipses?
I am writing a program to simulate eclipses for about -2000 to 6000. My question is, how accurate does my ephemeris for the sun and moon have to be to get a decent accuracy for eclipses? I currently ...
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Is it correct to say vertical conjunction?
This question is related to this one: Are we seeing a conjunction these mornings?
Last Feb 27, the a reporter said that, the day before, at sunset, Venus and the Moon were in vertical conjunction. Is ...
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Precision in the measurement of the distance to the Sun
How precisely can the distance to the Sun be measured? Wikipedia says the distance to the Moon can be measured upto millimeter precision. But Wikipedia article on distance to the Sun says only about ...
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How can I calculate 27 tropical/solar year since my birthdate?
Let's say I was born on 27th November 1993 at 03:15:15 AM. Is there any way I can calculate exact 27 tropical cycle since my birthdate/birthtime.
What date and what time it will be after exact 27 ...
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L2 point ephemeris (celestial mechanics)
I'm a master student and I am trying to get the L2 ephemeris for some calculations in my master's project. It was kinda hard to find a file with the L2 ephemeris, but once I found it, I tried the next ...
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Why does the Earth have a z-component at the start of the J2000 epoch?
When I go to the NASA HORIZONS webpage
https://ssd.jpl.nasa.gov/horizons.cgi
and ask for the VECTOR coordinates of the Earth on 1 January 2000, it tells me that Earth has the following coordinates ...
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How to choose between methods to resample/interpolate ephemeris state vectors? Are there recognized techniques for orbital data?
I have ephemeris data for state vectors of a satellite in a J2000.0 coordinate system. This data is already filtered and cleaned.
The data sample rate ranges between 1 second and 60 seconds, and I ...
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How to calculate the ground track of the Moon's position on the Earth's surface?
I would like to project the Moon's position on to the surface of the Earth, starting with its position expressed as Right Ascension in degrees.
I know that the declination of the Moon corresponds to ...
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How to get ephemeris data for location?
How can I obtain ephemeris data which fits to a specific location? Differently phrased: I need ephemeris data of satellites which orbited a specific location. Is there a document where I can look up ...
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Calculating right ascension for two planets and their separation using python
I am experimenting with the Python library PyEphem for astronomy, and I am trying to recreate/understand some of the basic calculations there.
There is a function called separation that, given two ...
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Why is the time between equinoxes different?
The path of the Earth around the sun is described as being an ellipse, with the Sun being at one of the foci of the ellipse.
Since an ellipse, by definition, is symmetrical with respect to the foci, I ...
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Predicting accurate time of local sunrise in mountainous area?
Is there any software which will tell me accurately at what moment any part of the solar disk will become from a specific point on the ground taking account of terrain. I feel like Google maps should ...
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Ephemeris data mismatch between Nasa Horizonz and Astro.com
I have tried to compare the Ephemeris data from Nasa's Horizons with ephemeris
tables from astro.com. And they do not match. Example:
Date: 22th of July 2018. Body: Mars. Time 00:00 UT
Horizons: 309 ...
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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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What is the official classification and naming system of objects in the universe(, or what would my URI look like)?
Poetic human centric approach:
Universe/Laniakea/Virgo/MilkyWay/Sol/Earth/Humans/AndreasT
Little bit more technical:
...
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Which kernel does HORIZONS get the Geometric Albedo from?
I am new to using SPICE and the SPICE Toolkit. My goal is to extract body radius, albedo, and distance from the sun of a number of solar system objects. The tools provided by NAIF are great and I ...
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Where to get rate of change for calculating ephemeris from JPL Horizons
I have a working implementation of Schlyter's method for calculating the Sun's position. I would like to know how Schlyter got the 3.24587E-5_deg in the following calculation for Mercury.
...
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JPL Horizons - how to format TLIST input times for Email query?
I am trying to get a list of all of Mercury's Perihelia and Aphelia over a period of multiple decades. For each event I need X,Y,X and Vx,Vy,Vz data.
Knowing the time of the first event it is easy to ...
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Determination of High-Accuracy Distances of Terrestrial Planets from the Sun
I understand how in olden days the Sun-Planet distances were estimated using:-
(i) measures of planet orbital periods ($T$) from analysis of observations over several centuries;
(ii) Kepler's 3rd Law $...
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Difference in Ephemerides Position:- PlanEph 4.2 (VSOP87) vs JPL Horizons (DE431)
I have obtained the hindcast position of Mercury relative to the Sun for the epoch 2000-Jan-01 12:00:00 using two methods: PlanEph ver 4.2 (Dos-based) and JPL Horizons DE431 (online).
The two methods ...
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Finding Asteroid Geocentric Longitude and Latitude
I started using the software that comes with Jean Meeus book Astronomical Algorithms. I am now using the updated code from naughter(dot)com/aa.html.
I am able to calculate the heliocentric longitude ...
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where to obtain ephemeris data for geodesy satellites?
Is anyone aware of where one can obtain ephemeris data in Geocentric Celestial Reference Systems (GCRS) coordinates for a geodesy satellite such as LAGEOS (It doesn't really matter which mission)? Or, ...
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Converting Earth Moon Barycenter coordinate to Geocentric coordinate
I have Earth Moon Barycenter coordinate (J2000) generated from VSOP2013 in Astronomical Units,
...
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How to visually chart HORIZON ephemeris
I'm trying to build a 3D model of the Sun, Earth and Moon in in Javascript (using Three.JS, which relies on x,y,z coordinates for all objects) in order to simulate the Aug. 21 eclipse. I've ...
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calculating lunar phases
Given a date, I'd like to return the lunar phase.
Jean Meeus's Astronomical Algorithms book and the many packages like PyEphem that make use its algorithms provide ways to calculate when a primary ...
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How Can I Interpolate Ephemerides?
I have two ephemerides for orbital elements—that is, each contains $a$ (semi-major axis), $e$ (ecc.), $i$ (incl.), $\Omega$ (long. asc. node), $\omega$ (arg. of peri.), $\tau$ (time of peri.), $T$ (...
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JPL DE Documentation
I'm currently trying to write a C++ library that makes accessing binary data from a JPL ephemeris file easier. So far I sifted through the web, trying to find a good and thorough documentation about ...
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Is there an English translation of the Parisian Alfonsine tables
I'm interested in the Alfonsine tables published in Paris in the 1400s. I know there is an English translation of what survived of earlier Alfonsine tables from Castile, but that's not what I'm ...
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How to calculate the current distance between two planets [duplicate]
I'd like to add a feature to one of my apps that calculates the current distance between the Earth and Mars (or any other planet, for that matter). My google searches have led me to statistics of ...
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How can we map masses orbiting the outer Solar System by determining the orbits of planets and smaller objects?
Neptune was discovered 170 years ago with the help of observations of Uranus' orbit. A great demonstration of the scientific principle for its time. Recently, Earth and cis-Lunar based radio ...
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Did the Juno mission locate Jupiter at the same precision as Saturn (4 km)?
Juno's low perijove should be great for measuring Jupiter's gravitational effect on Juno's orbit. Cassini together with VLBI has measured Saturn's location to within 4 km.
Will Was Juno be able to ...
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Exactly what in Saturn has been located to within 4 km precision?
Saturn has been located with fantastic precision thanks to Cassini and VLBI. The location of the 120,000 km diameter giant planet (when defining the 1 bar pressure level as its surface) is known to ...
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