Astrometry Data Exchange Standard. Describes how information can be formatted to allow position and brightness information of an astronomical object to be stored in for instance, a simple text file. Supersedes and is more flexible than the previous format used by the Minor Planet Center, known as the 80-column MPC1992 format. See the MPC's July 2018 ADES announcement and their ADES Data submission page at, together with the Concise Description of the ADES standard document at


A Windows program by Herbert Raab providing professional quality astrometric reduction, track & stack, automated moving object detection functionality and more. See Astrometrica integration.

Versions of Astrometrica up to 4.11 generate astrometry data files in MPC1992 format, but from version 4.12 onwards generate ADES PSV formatted text files only.

Version 4.11 is available from the Astrometrica Downloads page at but the ADES version, announced in July 2018 in message #6994  on the Astrometrica message forum is still (March 2022) only available as a beta version, direct download of the zip file is available from


Object class is a value of 1, 2 or 3 assigned to NEOCP objects by the MPC and can be used in Ephemeris Interpolator to filter NEOCP objects. The exact meaning of the values appears to be undocumented but the assigned values are listed on an old version of the NEOCP at:

Object class 1 is generally assigned to newly discovered NEOs.

Object class 2 is generally assigned to newly discovered objects that  have a lower probability of being NEOs.

Object class 3 is generally assigned to objects that may be of interest but not necessarily NEOs. Often PCCP objects are assigned a class of 3.



Measurement on the celestial sphere, equivalent to latitude on Earth. See RA and the wiki article


A list of positions (Right Ascension and Declination, or RA and Dec) and often motion information (speed and direction of motion, or P.A.°) for a range of times for a moving object in the sky (comets, minor planets and also artificial satellites). To be suitable for use in Ephemeris Interpolator the list of times must be evenly spaced, e.g. hourly.

Ephemeris format

Defines the location of where Date, Time, RA, Dec, Speed and P.A.° are to be found in an ephemeris. Ephemeris formats are stored internally in Ephemeris Interpolator and can be viewed and edited in the Ephemeris Format Editor.


As applied to the Ephemeris Interpolator this is the estimation of RA, Dec, Speed and P.A.° for a date and time outside the range of dates in a set of astrometric positions. See Using astrometric lines to interpolate and extrapolate.


A program written by Bill Gray, used to calculate orbital elements from astrometric observations. It can also generate ephemerides and these can be imported directly into Ephemeris Interpolator, see Find_Orb integration. See for Find_Orb documentation and downloads.


Google Sky allows deep images of the sky to be viewed in detail. Available as a browser based  app on the internet but also as a Desktop application via Google Earth Pro, then switching to Sky mode. Integration with Ephemeris Interpolator is only possible with the Desktop application version, see GoogleSky integration.


See JPL Horizons


As applied to the Ephemeris Interpolator this is the estimation of values of RA, Dec, Speed and P.A.° for a date and time within the range of dates in an ephemeris. Depending on the distribution of the ephemeris dates around the required date, the rate of change of the quantities is used to provide better estimates for intermediate times.


The Jet Propulsion Laboratory (JPL) Center for NEO Studies (CNEOS) is the home of JPL’s Sentry impact monitoring system, which performs long-term analyses of possible future orbits of hazardous asteroids, searching for impact possibilities over the next century.


The JPL CNEOS Scout system monitors the MPC NEOCP webpages of new potential asteroid discoveries and computes the possible range of future motions before these objects have been confirmed as discoveries. Scout provides orbital, ephemeris and hazard assessment information for these NEOCP objects.

JPL Horizons

The JPL Horizons system provides access to solar system data and customizable production of accurate ephemerides for observers, mission-planners, researchers, and the public, by numerically characterizing the location, motion, and observability of solar system objects as a function of time, as seen from locations within the solar system.

The online Horizons system is available at

Documentation for the online system is at


The Jet Propulsion Laboratory's (JPL) Solar System Dynamics (SSD) group provides information related to the orbits, physical characteristics, and discovery circumstances for most known natural bodies in our solar system.


The Minor Planet Center is the single worldwide location for receipt and distribution of positional measurements of minor planets, comets and outer irregular natural satellites of the major planets.


A format for storing astrometry data, defined by the Minor Planet Center in 1992 and still in use today, though gradually being replaced by the ADES format. Individual lines are limited to a length of 80 characters.

MPC DB Search

The MPC Database Search service allows astrometry for designated Minor Planets and Comets to be retrieved from the MPC's database, not for objects on the NEOCP or PCCP. It can also be used to search for objects by object type or by orbit properties.

MPC packed format

In MPC1992 formatted astrometry, the identifiers used for permanently numbered objects or objects with provisional designations are converted into "packed" format to save space in the fixed 80-column astrometry line. See the MPC Packed Provisional and Permanent Designations page and the Pack and Unpack MPC Designations application overview on the Great Shefford website at


The MPC's Minor Planet and Comet Ephemeris Service, available at


The MPC's Near-Earth Object Confirmation Page, where unconfirmed newly discovered unusual asteroids are listed, so that observers can attempt to confirm and follow-up by submitting positional measurements. Possible comets are linked on the NEOCP to the Possible Comet Confirmation Page (PCCP).

The information from the NEOCP is shared with the Scout system, which provides an independent source of predictions.

The NEOCP can be accessed at:


A web service developed by the Catalina Sky Survey team.

NEOfixer aims to help optimize the discovery and follow-up of Near-Earth Objects (NEOs) by providing observers with targeting recommendations, specific to their site. A by-product of the service is the generation of ephemerides for NEOs, comets and NEOCP objects and these can be downloaded automatically into Ephemeris Interpolator if the observer has an MPC observatory code and creates an account on NEOFixer. See the NEOFixer FAQ for more information.

Object Class

See Class.


Position Angle. The angle, measured relative to the North Celestial Pole of the direction of motion of a moving solar system object. The convention adopted in Ephemeris Interpolator is that used by the MPC, where North = 0°, East = 90°, South = 180° and West = 270°.


The MPC's Possible Comet Confirmation Page, where unconfirmed newly discovered comets are listed, so that observers can attempt to confirm and follow-up by submitting positional measurements. The PCCP is for comets the equivalent of the NEOCP for near-Earth asteroids.

The PCCP can be accessed at:


An optional extra identifier to the Object name, entered in the toolstrip. The combination of Object and Qualifier makes an object name unique in the list of tabs in Ephemeris Interpolator. For MPES and NEOCP objects, a numeric variant orbit number can be entered as a qualifier to retrieve an ephemeris for that variant.

Right Ascension


Measurement on the celestial sphere, equivalent to longitude on Earth. See Dec and the wiki article




Observer-assigned tracklet identifier, an identifier given to the same object in a set of measurements during one night. A NEOCP temporary identifier is normally the trkSub from the discovery observations of a new object. trkSub is used in ADES submissions and is typically the same as the observer-assigned temporary designation previously employed for the MPC1992 format.


One of a set of possible orbits (and therefore predicted positions) for a solar system object. The Minor Planet Center provides predictions for a number of different possible orbits (variants) via their MPES and NEOCP online services. MPC variants are identified by a number in square brackets following the ID of the related object, e.g. C2X9AZ1[1784] refers to variant orbit 1784 for NEOCP object C2X9AZ1.

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