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What the MPC API responses actually mean: Welcome to the constelatio-express wiki!

rms: root mean square epoch: epoch of osculation - units: ET in packed form, .0 tt readeable_des : Temporary designation or permanent number for this object. Assigned by the Minor Planet Center. H: Absolute Magnitude is an intrinsic measure of brightness. It is the apparent magnitude of the object when it is 1 AU from both the sun and the observer, and at full phase for the observer. num_obs: number of observation ref: numerical reference code G: magnitude slope parameter (default is 0.15) last_obs: date of last observation comp: Computer used (default answer MPCLINUX) M: mean anomaly at epoch, degrees

U: Orbit condition code?

OR

Uncertainty parameter, U - If this column contains E it indicates that the orbital eccentricity was assumed. For one-opposition orbits this column can also contain D if a double (or multiple) designation is involved or `F' if an e-assumed double (or multiple) designation is involved?

e: eccentricity a: semimajor axis (AU) om: Longitude of ascending node (deg)- j2k degrees pert_p: precise indicator of pert d: mean daily motion (deg/day) i: Inclination (deg) des: designation (number that corresponds to flags: (see below) num_opp: num opp can be blank w: Argument of perihelion (deg) pert_c: coarse indicator of pert

162 - 165 z4.4 4-hexdigit flags The bottom 6 bits (bits 0 to 5) are used to encode a value representing the orbit type (other values are undefined):

                 Value

2 Aten - Aten asteroids -- whose orbits also cross Earth's orbit, but unlike Apollos, Atens spend most of their time inside Earth orbit.

3 Apollo - Apollo asteroids -- whose orbits cross Earth's orbit. Apollo asteroids spend most of their time outside Earth orbit. Technically, they have wider orbits than Earth.

4 Amor - Amor asteroids -- whose orbits approach but do not cross Earth orbit, and whose orbits are further from the Sun than Earth's orbit. Many have orbits which reside entirely between Earth and Mars.

5 Object with q < 1.665 AU - perihelion distance is less than q

6 Hungaria - asteroids orbitting the sun with a distance (semi-major axis) between 1.78 and 2.00 AU

7 Phocaea

8 Hilda - The Hilda or Hildian asteroids are a dynamical group[1] of asteroids in a 3:2 orbital resonance with Jupiter. Hildas move in their elliptical orbits so that their aphelia put them opposite Jupiter, or 60 degrees ahead of or behind Jupiter at the L4 and L5 Lagrangian points. Over three successive orbits each Hilda asteroid passes through all of these three points in sequence. Consequently, a Hilda's orbit has a semi-major axis between 3.7 AU and 4.2 AU, an eccentricity less than 0.3, and an inclination less than 20°.Two collisional families exist within the Hilda group: the Hilda family and the Shubart family.[4] The namesake is 153 Hilda, discovered by Johann Palisa in 1875. There are more than 1,100 known Hilda asteroids including unnumbered objects

9 Jupiter Trojan - The Jupiter Trojans, commonly called Trojans or Trojan asteroids, are a large group of objects that share the orbit of the planet Jupiter around the Sun. Relative to Jupiter, each Trojan librates around one of Jupiter's two stable Lagrangian points, L4 and L5, that respectively lie 60° ahead of and behind the planet in its orbit. Jupiter Trojans are distributed in two elongated, curved regions around these Lagrangian points with an average semi-major axis of about 5.2 AU

10 Centaur - Centaurs are small Solar System bodies with a semi-major axis between those of the outer planets. They have unstable orbits that cross or have crossed the orbits of one or more of the giant planets, and have dynamic lifetimes of a few million years.Centaurs typically behave with characteristics of both asteroids and comets.

14 Plutino - In astronomy, a plutino is a trans-Neptunian object in 2:3 mean motion resonance with Neptune. For every 2 orbits that a plutino makes, Neptune orbits 3 times. Plutinos are named after Pluto, the first discovered object with this resonance. The name refers only to the orbital resonance and does not imply common physical characteristics.

15 Other resonant TNO - In astronomy, a resonant trans-Neptunian object is a trans-Neptunian object (TNO) in mean motion orbital resonance with Neptune. The orbital periods of the resonant objects are in a simple integer relations with the period of Neptune e.g. 1:2, 2:3 etc. Resonant TNOs can be either part of the main Kuiper belt population, or the more distant scattered disc population.

16 Cubewano - A classical Kuiper belt object, also called a cubewano is a low-eccentricity Kuiper belt object (KBO) that orbits beyond Neptune and is not controlled by an orbital resonance with Neptune. Cubewanos have orbits with semi-major axes in the 40–50 AU range and, unlike Pluto, do not cross Neptune’s orbit. That is, they have low-eccentricity and sometimes low-inclination orbits like the classical planets.

17 Scattered disk - The scattered disc (or scattered disk) is a distant region of the Solar System that is sparsely populated by icy minor planets, a subset of the broader family of trans-Neptunian objects. The scattered-disc objects (SDOs) have orbital eccentricities ranging as high as 0.8, inclinations as high as 40°, and perihelia greater than 30 astronomical units (4.5×109 km; 2.8×109 mi). These extreme orbits are believed to be the result of gravitational "scattering" by the gas giants, and the objects continue to be subject to perturbation by the planet Neptune. Although the closest scattered-disc objects approach the Sun at about 30–35 AU, their orbits can extend well beyond 100 AU

                Additional information is conveyed by
                adding in the following bit values:

           Bit  Value
             6     64  Unused
             7    128  Unused
             8    256  Unused
             9    512  Unused
            10   1024  Unused
            11   2048  Object is NEO (Near Earth Object)
            12   4096  Object is 1-km (or larger) NEO
            13   8192  1-opposition object seen at
                       earlier opposition
            14  16384  Critical list numbered object
            15  32768  Object is PHA - (potentially hazardous asteroid)

                Note that the orbit classification is
                  based on cuts in osculating element
                  space and is not 100% reliable.