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Joshua Turner
Joshua Turner


In astronomy and celestial navigation, an ephemeris (pl. ephemerides; from Latin ephemeris 'diary', and Greek ἐφημερίς (ephemeris) 'diary, journal')[1][2][3] is a book with tables that gives the trajectory of naturally occurring astronomical objects as well as artificial satellites in the sky, i.e., the position (and possibly velocity) over time. Historically, positions were given as printed tables of values, given at regular intervals of date and time. The calculation of these tables was one of the first applications of mechanical computers. Modern ephemerides are often provided in electronic form. However, printed ephemerides are still produced, as they are useful when computational devices are not available.



The astronomical position calculated from an ephemeris is often given in the spherical polar coordinate system of right ascension and declination, together with the distance from the origin if applicable. Some of the astronomical phenomena of interest to astronomers are eclipses, apparent retrograde motion/planetary stations, planetary ingresses, sidereal time, positions for the mean and true nodes of the moon, the phases of the Moon, and the positions of minor celestial bodies such as Chiron.

For scientific uses, a modern planetary ephemeris comprises software that generates positions of planets and often of their satellites, asteroids, or comets, at virtually any time desired by the user.

Celestial navigation serves as a backup to Satellite navigation. Software is widely available to assist with this form of navigation; some of this software has a self-contained ephemeris.[9] When software is used that does not contain an ephemeris, or if no software is used, position data for celestial objects may be obtained from the modern Nautical Almanac or Air Almanac.[10]

An ephemeris is usually only correct for a particular location on the Earth. In many cases, the differences are too small to matter. However, for nearby asteroids or the Moon, they can be quite important.

This area contains printable ephemeris files in PDF format.This format allows to view and print ephemerides in excellent quality.Each ephemeris file covers one year and prints on six pages, withtwo months per page.

The ephemeris contains the regular planets, Sun, Moon, Mercury, Venus, Mars, Jupiter,Saturn, Uranus, Neptune, Pluto.The ephemeris also contains the Lunar Nodes True Node and Mean Node,the minor planet Chiron and the mathematical point 'Lilith' or 'Dark Moon',technically known as the Lunar Apogee.

The links appearing as numbers contain the ephemeris for this year; thelinks 'A' contain a list of mundane aspects (aspects formed by the movingplanets on the sky). For years marked with 'j' like 1500j the Ephemeris is inthe Julian Calendar, otherwise it is in the Gregorian Calendar.

These printable ephemeris files were created from the Swiss Ephemeris library.Swiss Ephemeris is a highly precise ephemeris toolbox available as sourcecode and as a DLL. Please see Swiss Ephemeris for Programmers.

An ephemeris (plural: ephemerides) gives the trajectory of naturally occurring astronomical objects in the sky, i.e., the position (and possibly velocity) over time.T: 1 (877) 292-0667E:

Minor Planet & Comet Ephemeris ServiceThis webpage serves three purposes:To allow an observer to get ephemerides (utilizing the latest published elements) and/or elements for an arbitrary set of (up to 100 at a time) minor planets or comets.To allow an observer to check the current observability of an arbitrary set of (up to 100 at a time) minor planets, then to get ephemerides and/or elements for those deemed to be observable.To allow an observer to prepare an HTML document that can be placed on their own website, with the aim of encouraging others to perform follow-up astrometry of their minor planet discoveries. Of course, this facility can also be used to generate a page for any arbitrary set of minor planets. Once a page has been placed on your site, you can forget about it. You do not need to update the page as orbits are improved or as objects are identified or numbered--this is all handled transparently by this service. You need only modify the page as you discover new objects. In either case, enter your list of desired objects in the text-area indicated.By default, ephemerides will be returned. If you desire a HTML documentto be returned, check the appropriate box. Further options, specific to eachpurpose are accessible further down this page.A PDF document (633 KB) describing the use of the MPESis available. (Updated 2011 Jan. 14)Information on any known problems with thisservice is available.Report a problem.Comment on this service.Why can't I find an object with a particular name? (Added 2004 Sept. 7)Note: If you wish an ephemeris for the main component of comet C/2019 Y4 (ATLAS), please enter CK19Y04b

An ephemeris is a set of data that provides the assigned places of a celestial body (including a manmade satellite) for regular intervals. Definitive Ephemeris shows the position and velocity of the spacecraft at the time imagery is collected, and shows the position and velocity of the satellites in one-minute intervals.

Banneker, Benjamin, and American Almanac Collection. Benjamin Banneker's Pennsylvania, Delaware, Maryland, and Virginia almanack and ephemeris, for the year of Our Lord. Baltimore: Printed and sold ... by William Goddard and James Angell, 1792. Periodical.

Banneker, B. & American Almanac Collection. (1792) Benjamin Banneker's Pennsylvania, Delaware, Maryland, and Virginia almanack and ephemeris, for the year of Our Lord. Baltimore: Printed and sold ... by William Goddard and James Angell. [Periodical] Retrieved from the Library of Congress,

Banneker, Benjamin, and American Almanac Collection. Benjamin Banneker's Pennsylvania, Delaware, Maryland, and Virginia almanack and ephemeris, for the year of Our Lord. Baltimore: Printed and sold ... by William Goddard and James Angell, 1792. Periodical. Retrieved from the Library of Congress, .

A custom ephemeris can be created using the CreateEphemeris action in the AWS Ground Station API. This action will upload an ephemeris using data either in the request body or from a specified S3 bucket.

It is important to note that uploading an ephemeris sets the ephemeris to VALIDATING and starts an asynchronous workflow that will validate and generate potential contacts from your ephemeris. Only once an ephemeris has passed this workflow and become ENABLED will it be used for contacts. You should poll DescribeEphemeris for the ephemeris status or use Cloudwatch events to track the ephemeris' status changes.

The AWS Ground Station boto3 client can be used to upload a two line element (TLE) set ephemeris to AWS Ground Station via the CreateEphemeris call. This ephemeris will be used in place of the default ephemeris data for a satellite (see Default Ephemeris Data).

This call will return an ephemeris Id that can be used to reference the ephemeris in the future. For example, we can use the provided ephemeris ID from the call above to poll for the status of the ephemeris:

It is recommended to poll the DescribeEphemeris route or use Cloudwatch events to track the status of the uploaded ephemeris as it must go through an asynchronous validation workflow before it is set to ENABLED and becomes usable for scheduling and executing contacts.

It is also possible to upload an ephemeris file directly from an S3 bucket by pointing to the bucket and object key. AWS Ground Station will retrieve the object on your behalf. Information about the encryption of data at rest in AWS Ground Station is detailed in: Data Encryption At Rest For AWS Ground Station

An ephemeris file is an ASCII text file formatted for compatibility with STK that ends in a .e extension. Ephemeris files can be useful when you need to provide STK with position and velocity data for a vehicle to model certain unique circumstances. Vehicle ephemeris is a Basic property of all vehicles in STK. The ephemeris data - organized in a properly formatted table - in any ephemeris file can be imported into STK using the StkExternal propagator.

STK uses ephemeris data to generate the position and velocity of a vehicle at whatever time values it needs to support analysis and animation. When necessary, STK will interpolate between points to do so. Interpolation is performed in the same coordinate frame (inertial or fixed) that the data is supplied in.

Each ephemeris table, regardless of the type of ephemeris data in the table, contains some common elements called keywords. Keywords and their associated values must precede the specification of the ephemeris format and the actual data points.

Without this keyword, smoothness of ephemeris data is determined based on vehicle and progagator types. Ground vehicle, ship, and aircraft objects, as well as any file that declares interpolation to be based on a great arc type, are assumed to have non-smooth data. Otherwise, data is assumed to be smooth.

The coordinate system in which the ephemeris points reside. Normally, the coordinate system is the name of a valid coordinate system for the central body specified above (see Central Body Coordinate Systems). Typically, each central body supports Fixed, J2000, ICRF, Inertial, TrueOfDate, and MeanOfDate though certain bodies support additional systems.

If your ephemeris is not in one of STK's predefined coordinate systems, you must define a new coordinate system using the Vector Geometry Tool. You may then specify the name of your new coordinate system and the name of the STK object to which it corresponds using the Custom coordinate system.

While the sections above outline the basic format for an ephemeris table, the sections below outline the formats used to specify actual data points in the ephemeris table. The format keyword must be included in the file on its own line, after the header keywords and before the actual data point array. 041b061a72


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