Astronomical Observatory: Cool Images

Asteroids

Table of Calvin College Asteroid Discoveries

LATEST NEWS:

March 21, 2011: Asteroids 2005 YO, 2008 DU4, 2009 AF17, and 2009 WD25 received the permanent designations 268488, 269147, 269374, and 269554, respectively.

[See a chronology of previous asteroid discovery news.]

The Minor Planet Center (MPC) credits Calvin College with the discovery of 321 asteroids as of 4/4/11 (principal designations). Of these, 77 have been given permanent designations. (An additional 41 asteroids were given provisional designations that are now considered secondary designations.) The table below summarizes the essential information on these objects (name, discovery circumstances, orbital parameters as determined by the MPC, size, and the circumstances of the next close approach to Earth). Active links for each asteroid link to a 3D interactive orbit visualization tool from the NASA Near Earth Object Program. Descriptions of each column are given below.

Designation: Asteroid positional measurements are reported to the MPC, which evaluates the measurements for quality, compares them to positions of known asteroids, and assigns provisional designations to newly discovered asteroids. These designations indicate the approximate date of discovery: a four digit year, a letter based on the half-month within which the first measurement was made, and an alphanumeric value denoting the order of discovery within the halfmonth (cf. the detailed description of the nomenclature).

To define the orbit of an asteroid precisely, observations over a number of years are required. Asteroids for which adequate observations have been made at four or more oppositions have orbits established well enough that they will never be lost or confused with other objects. These receive a permanent designation, a six digit serial number.

Discovery Circumstances:

Date: Date of first observation of asteroid by Calvin College.

Orbit: Asteroid orbits are modeled as Keplerian ellipses, the shape of which are determined by the average distance from the Sun (the semimajor axis, a, in units of the Earth-Sun distance, the AU) and the eccentricity (e). The orbits are generally tilted with respect to the plane of the Earth's orbit by an inclination, i (in units of degrees). The values given here are osculating elements computed by the Minor Planet Center. For the current position and brightness and the status of observations of any asteroid, try their Minor Planet Ephemeris Service. To visualize the orbits of our asteroids, simply click on the asteroid name in the table above.

Size: This column gives the absolute magnitude, H, of each asteroid, the brightness as it would be seen from a standard distance. The units are logarithmic with smaller numbers indicating brighter objects. The absolute magnitude, combined with an estimate of the albedo (degree of reflectance of the surface), can be used to estimate the physical diameter of the asteroid using a conversion table. Our discoveries have absolute magnitudes ranging from 14.6 to 19.0, which roughly corresponds to diameters of 0.8 to 5 km. Were they to strike the Earth, the resulting impact craters would be about 10 to 50 km across.

Arc: To make an accurate determination of an asteroid's orbit, its position must be observed over a wide range of time. For asteroids seen in only one opposition, this column give the range of days over which it was observed. Otherwise, this column gives the number of different oppositions in which the asteroid was detected.

Miscellaneous: For a number of the asteroids only two nights of data could be obtained, so no reasonable estimate of the orbital parameters could be made.

updated 4/8/11 by L. Molnar

Secondary

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