Originally collected from the literature by
Per Magnusson at the time working at the Uppsala Observatory (Sweden).
Latest version of 1995 Dec 29.
Currently maintained by
Agnieszka Kryszczyńska from the
Astronomical Observatory, A. Mickiewicz University, Słoneczna 36, 60-286 Poznań, Poland.
Latest version of 2014 Feb 14.
New interface created by
Emil Wilawer within master thesis at the
Astronomical Observatory, A. Mickiewicz University.
Master thesis is available here.
This is a comprehensive tabulation of asteroid spin vector determinations. Supplementary information on shape models is also included, but only when part of a spin vector determination. To see individual solutions click on the asteroid name.
If you find omissions and errors or have suggestions for future improvements please contact me on agn @ amu.edu.pl .
Please use the following citation to reference this data set: Kryszczynska A., La Spina A., Paolicchi P., Harris A.W., Breiter S., Pravec P., 2007, New findings on asteroid spin-vector distributions, Icarus 192, 223-237.
The OLD version and related documentation is available here.
The terms "North Pole" and "South Pole" are ambiguous and they are avoided in this table. Instead I use the direction of the spin angular velocity vector, as defined by the "right-hand-rule". Note that a full specification of the spin vector makes it superfluous to use the ambiguous terms "prograde rotation" and "retrograde rotation". These are ambiguous since the sense of rotation can be based on the ecliptic plane, the asteroid's orbital plane, or something else (the truth usually depends in a complicated way on the distribution of serving geometries).
For some asteroids a large number of independent solutions have been published. This may be confusing for readers who are not interested in the spin vector determination process as such. For the benefit of readers who just want reliable results for their own applications I include a "synthesis" of our knowledge for some asteroids. I estimate that these synthesis results have a high reliability and an accuracy in the spin vector direction of order 10 degrees or less. They were obtained by taking averages of the most recent independent results, with weights based on the method used and the amount and type of the input data. This procedure is necessarily somewhat subjective, and can't replace a careful evaluation of the original results.
METHOD
The data from which the spin vectors and rejections of spurious solutions are based are designated by the letters:
A = Amplitudes of lightcurves
B = ADAM - All-Data Asteroid Modelling algorithm (optical lc + radar data + stellar occ. + disc resolved images)
C = Close observations from spacecraft during fly-by or rendezvous
D = Individual data-points of photometric lightcurves
E = Epochs (e.g. times of lightcurve extrema)
F = Fourier coefficients of photometric lightcurves
I = Infrared pre- and post-opposition differences
K = KOALA algorithm (optical lc + stellar occ. + disc resolved images)
L = Lightcurve inversion based on lightcurves
L* = Lightcurve inversion based on lightcurves and sparse data
L** = Lightcurve inversion based on sparse data only
M = Magnitudes (usually at maximum light)
O = Occultation observations
P = Infrared polarimetry
R = Radar observations
S = Surface resolved (e.g. speckle data, adaptive optics)
T = Thermophysical modelling
V = Visual position angles
X = Radar speckles
Z = Zero and non-zero amplitude apparitions imply pole-on view in former case
SPIN VECTOR SOLUTIONS (λ, β)
The direction of the spin vectors (defined by the "right-hand-rule") are given in degrees in the ecliptic system for equinox J2000.0. Some older determinations where obtained in the ecliptic system for equinox B1950.0, however the difference in longitudes (about 0.7°) is far below the level of accuracy of the spin vector solutions.
The table contains column space for four spin vector directions per line. These reflect the symmetry properties of most spin vector determinations. Methods based on aspect dependences (e.g. amplitude and magnitude methods) tend to give two spin axis solutions for main-belt asteroid with moderate orbital inclination (due to the near symmetry of the observational geo-metries in the ecliptic plane). Corresponding to each spin axis solution we have two opposite spin vector directions, which are given explicitly in the table. Thus, whenever the method used does not contain information on the sense of rotation I interpret "poles" as spin axis solutions and calculate the implicit spin vector directions. The result is generally four different solutions. I try to put the two prograde ones in the two left columns the two retrograde ones in the columns to the right. If subsequent determinations agree reasonably then corresponding solutions appear in the same column, making comparison easy. The 4-fold symmetry is not applicable to certain objects. The distinction between the four groups may break down for objects in high inclination orbits (e.g. 2 Pallas), for objects with spin axes close to the ecliptic plane, and for objects whose lightcurves are difficult to interpret (e.g. 532 Herculina). For Earth-approaching objects it often reduces to a 2-fold clustering. The newest spin vector determination methods give single best fitted solution.
SIDEREAL PERIOD
Only periods accurate enough to bridge inter-apparitional gaps and produce absolute rotational phases for the whole data set are included. Less accurate synodic period determinations exist for many more objects. As evident from the table, the agreement between sidereal period determinations tend to be either very good or very bad. This is due to the non-uniform time-distribution of the observations, which tend to give many well-defined local chi-square minima.
ELLIPSOIDAL MODEL (a⁄b, b⁄c)
Many pole determination methods are based on a tri-axial ellipsoid model with semi-axes a≥b≥c rotating about the c-axis. Corrections for non- geometric scattering and albedo variegation have often not been made. A warning must therefore be made against direct identification of the model axis-ratios with the asteroid shape. Note that the table is not a comprehensive list of asteroid shapes, but includes models obtained as by-products of spin vector determinations only.
REFERENCE CODE
The reference codes are formed by 2-3 letters of the first author name, followed by '+' if there are more authors, and the last two digits of the publication year. Full expansions of the codes are given in the reference list.