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Questions tagged [ephemeris]

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1answer
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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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1answer
37 views

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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1answer
118 views

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, ...
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1answer
121 views

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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1answer
64 views

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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2answers
52 views

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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1answer
72 views

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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1answer
52 views

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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0answers
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How did Halley combine newton’s lunary theory with the saros cycle to predict eclipses?

I’ve read that halley combined Newton’s lunar motion model with the old knowledge of the saros cycle to predict eclipses. Unfortunately I can’t find any source that shows exactly how he did this, ...
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1answer
155 views

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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1answer
433 views

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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1answer
283 views

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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1answer
210 views

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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1answer
299 views

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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1answer
176 views

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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2answers
103 views

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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0answers
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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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1answer
1k views

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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1answer
51 views

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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0answers
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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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1answer
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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 ...