Asteroid Ephemeris BC405-A1


This is a numerically-integrated ephemeris of the 300 asteroids used in the force model of the JPL DE-405 planetary ephemeris; it accounts for the mutual perturbations of all 300 asteroids upon one another, in addition to perturbations from the Sun and planets.  

Like DE405, this ephemeris covers the years 1800 to 2200.  More specifically, entries begin at JD 2378495.0, and end at JD 2524615; there are a total of 3654 entries spaced at 40-day intervals.  For each date, the ephemeris entry consists of the six classical orbital elements 
a in AUs
e
i in radians
w in radians
omega in radians
M in radians
for each of the 300 asteroids.  Thus, the entry for each date consists of 1800 numbers.  Each line of the text file contains a single double-precision number; there are no blank lines; as the entry for one date ends, the entry for the next date begins.  The elements are in the heliocentric ecliptic frame, referred to J2000.

Thus, if we wish to find the classical elements for the i'th asteroid at the j'th time interval, we would seek the following lines of text:
a = line 300*(j-1) + 6*(i-1) + 1
e = line 300*(j-1) + 6*(i-1) + 2
i = line 300*(j-1) + 6*(i-1) + 3
w = line 300*(j-1) + 6*(i-1) + 4
omega = line 300*(j-1) + 6*(i-1) + 5
M = line 300*(j-1) + 6*(i-1) + 6


The order in which the asteroids are presented, and the masses assumed for each asteroid, are provided in the accompanying "mu.txt" file.

It should be noted that this ephemeris will likely be short-lived.  First, radar observations are currently available for only a handful of the 300 asteroids  depicted here; but as radar observatories are upgraded, they will be able to provide extremely precise delay and doppler observations of main belt asteroids with regularity.  Second, as the masses of these asteroids are deduced, their mutual perturbations will have to recalculated.  

Nevertheless, I sincerely hope this ephemeris will find use in high-precision applications such as collision analysis, mission design, and mass determination.  

Any questions should be directed to jimbaer1@earthlink.net 




Jim Baer
August 22, 2007