PDS_VERSION_ID = PDS3 /* File Characteristics */ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 106 FILE_RECORDS = 526 /* Data Object Pointers */ ^TABLE = "SPIN.TAB" /* Identification Keywords */ DATA_SET_ID = "A-5-DDR-ASTEROID-SPIN-VECTORS-V3.0" PRODUCT_NAME = "Asteroid Spin Vectors" PRODUCT_ID = "SPIN-SPIN-199604" INSTRUMENT_HOST_NAME = "N/A" INSTRUMENT_NAME = "N/A" TARGET_NAME = ASTEROID START_TIME = 1932 STOP_TIME = 1995 PRODUCT_CREATION_TIME = 1996-03-29 /* Peer Review Date */ RECORD_FORMAT = "(I5,1X,A5,2X,A1,4(2X,A1,1X,I3,1X,I3),2X, F10.8,2X,A1,1X,F4.2,1X,F4.2,2X,A6,2X,A10)" /* Data Object Descriptions */ OBJECT = TABLE ROWS = 526 ROW_BYTES = 106 INTERCHANGE_FORMAT = ASCII COLUMNS = 21 DESCRIPTION = " This dataset is identical in content to the asteroid spin vector compilation of Magnusson. The format has been modified to make it machine readable and consistent with PDS archiving standards. For a general description of the Uppsala Asteroid Database, of which this spin vectors compilation is a part, see the following reference. The Uppsala Asteroid database is available by anonymous ftp at ftp.astro.uu.se. Magnussen, P., C.-I. Lagerkvist, M. Dahlgren, A. Erikson, M. A. Barucci, I. Belskaya, and M. T. Capria 1993. 'The Uppsala Asteroid Database', Asteroids, Comets, Meteors 1993, A. Milani, M. diMartino, and A. Cellino, Eds. (Kluwer Academic Publishers, Dordrecht) pp. 471-476. The following description of the compilation has been modified slightly to be applicable to this PDS version of the compilation. ASTEROID SPIN VECTOR DETERMINATIONS collected from the literature by Per Magnusson Astronomiska observatoriet Box 515 S-751 20 Uppsala Sweden Per.Magnusson@astro.uu.se Version of 1995 December 29 This is a comprehensive tabulation of asteroid spin vector determinations. Supplementary information on shape models and albedo variegation is also included, but only when part of a spin vector determination. If you find omissions and errors or have suggestions for future improvements please contact me on the above address. Comments on the nomenclature used --------------------------------- 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 observing geometries). The exception is determinations of the sense of rotation only (no spin axis given), for which the published designations prograde and retrograde are repeated faithfully in the present table. Synthesis of independent results -------------------------------- 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. Explanation of table columns ----------------------------- BASIC DATA The data from which the spin vectors and rejections of spurious solutions are based are designated by the letters: A = Amplitudes of lightcurves 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 M = Magnitudes (usually at maximum light) O = Occultation observations P = Infrared polarimetry R = Radar observations S = Surface resolved (e.g. speckle data, adaptive optics) V = Visual position angles Z = Zero and non-zero amplitude apparitions imply pole-on view in the former case X = used where the solution was rejected based on a type of data not specified SPIN VECTOR SOLUTIONS The direction of the spin vectors (defined by the 'right-hand-rule') are given in degrees in the ecliptic system for equinox B1950.0. The corresponding ecliptic coordinates for equinox J2000.0 can be obtained by adding 0.7 degrees to all tabulated longitudes, but this adjustment is far below the level of accuracy for most spin vector determinations. 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. A result which demonstrates (explicitly or implicitly) that one of the four solutions can be rejected is indicated by a letter in the flag entry accompanying the affected solution. The letter indicates the type of data primarily responsible for the rejection (see table above). Rejection flags have not been used for asteroids where the solutions don't cluster in a clear way. 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 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. When a non-ellipsoidal model is used it is described in a note referenced in the final column of the table. Note that the table is not a comprehensive list of asteroid shapes, but includes models obtained as by-products of spin vector determinations only. ALBEDO VARIEGATION Albedo models are also often by-products of spin-vector determinations, and therefore noted in the table. However, the table is not a complete collection of such models. The notes referenced by the final column of the table give some additional information. 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, in the file 'spinref.tab'. " OBJECT = COLUMN NAME = "ASTEROID ID" DATA_TYPE = ASCII_INTEGER START_BYTE = 1 BYTES = 5 FORMAT = I5 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "BASIC DATA ID" DESCRIPTION = "The type of data on which the solutions in this entry have been based (see table above)." DATA_TYPE = CHARACTER START_BYTE = 7 BYTES = 5 FORMAT = A5 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "POLE SOLUTION FLAG" DESCRIPTION = "For results presenting sense of rotation only, with no spin axis given, the published designations 'prograde' and 'retrograde' are reported here as they were given in the original publication. This flag takes three values: P - prograde R - retrograde N - a note on this pole solution occurs in the 'note' column." DATA_TYPE = CHARACTER START_BYTE = 14 BYTES = 1 FORMAT = A1 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION ONE POLE FLAG" DESCRIPTION = "A letter in this column indicates that this solution has been rejected, primarily on the basis of the type of data corresponding to that letter (see the above table). " DATA_TYPE = CHARACTER START_BYTE = 17 BYTES = 1 FORMAT = A1 MISSING_CONSTANT = "_" END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION ONE POLE COORD LATITUDE" DESCRIPTION = "The null value for this field is '999'." UNIT = DEGREE DATA_TYPE = ASCII_INTEGER START_BYTE = 19 BYTES = 3 FORMAT = I3 MISSING_CONSTANT = 999 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION ONE POLE COORD LONGITUDE" DESCRIPTION = "The null value for this field is '999'." UNIT = DEGREE DATA_TYPE = ASCII_INTEGER START_BYTE = 23 BYTES = 3 FORMAT = I3 MISSING_CONSTANT = 999 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION TWO POLE FLAG" DESCRIPTION = "A letter in this column indicates that this solution has been rejected, primarily on the basis of the type of data corresponding to that letter (see the above table)." DATA_TYPE = CHARACTER START_BYTE = 28 BYTES = 1 FORMAT = A1 MISSING_CONSTANT = "_" END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION TWO POLE COORD LATITUDE" DESCRIPTION = "The null value for this field is '999'." UNIT = DEGREE DATA_TYPE = ASCII_INTEGER START_BYTE = 30 BYTES = 3 FORMAT = I3 MISSING_CONSTANT = 999 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION TWO POLE COORD LONGITUDE" DESCRIPTION = "The null value for this field is '999'." UNIT = DEGREE DATA_TYPE = ASCII_INTEGER START_BYTE = 34 BYTES = 3 FORMAT = I3 MISSING_CONSTANT = 999 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION THREE POLE FLAG" DESCRIPTION = "A letter in this column indicates that this solution has been rejected, primarily on the basis of the type of data corresponding to that letter (see the above table)." DATA_TYPE = CHARACTER START_BYTE = 39 BYTES = 1 FORMAT = A1 MISSING_CONSTANT = "_" END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION THREE POLE COORD LATITUDE" DESCRIPTION = "The null value for this field is '999'." UNIT = DEGREE DATA_TYPE = ASCII_INTEGER START_BYTE = 41 BYTES = 3 FORMAT = I3 MISSING_CONSTANT = 999 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION THREE POLE COORD LONGITUDE" DESCRIPTION = "The null value for this field is '999'." UNIT = DEGREE DATA_TYPE = ASCII_INTEGER START_BYTE = 45 BYTES = 3 FORMAT = I3 MISSING_CONSTANT = 999 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION FOUR POLE FLAG" DESCRIPTION = "A letter in this column indicates that this solution has been rejected, primarily on the basis of the type of data corresponding to that letter (see the above table)." DATA_TYPE = CHARACTER START_BYTE = 50 BYTES = 1 FORMAT = A1 MISSING_CONSTANT = "_" END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION FOUR POLE COORD LATITUDE" DESCRIPTION = "The null value for this field is '999'." UNIT = DEGREE DATA_TYPE = ASCII_INTEGER START_BYTE = 52 BYTES = 3 FORMAT = I3 MISSING_CONSTANT = 999 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SOLUTION FOUR POLE COORD LONGITUDE" DESCRIPTION = "The null value for this field is '999'." UNIT = DEGREE DATA_TYPE = ASCII_INTEGER START_BYTE = 56 BYTES = 3 FORMAT = I3 MISSING_CONSTANT = 999 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SIDEREAL PERIOD" DESCRIPTION = "The null value for this field is 0." UNIT = DAY DATA_TYPE = ASCII_REAL START_BYTE = 61 BYTES = 10 FORMAT = "F10.8" MISSING_CONSTANT = 0. END_OBJECT = COLUMN OBJECT = COLUMN NAME = "SHAPE MODEL FLAG" DESCRIPTION = " This flag can take the following values: A - An albedo model was used. Refer to comment in note column. N - Refer to comment in note field. The null value for this field is an underscore character '_'. " DATA_TYPE = CHARACTER START_BYTE = 73 BYTES = 1 FORMAT = A1 MISSING_CONSTANT = "_" END_OBJECT = COLUMN OBJECT = COLUMN NAME = "A OVER B MODEL" DESCRIPTION = " Many pole determination methods are based on a tri-axial ellipsoid model with semi-axes a > b > c which rotates 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. When a non-ellipsoidal model is used, the model is described in a note in the note column. The table is not a comprehensive list of asteroid shapes and albedo models, but includes models obtained as by-products of pole determinations only. The null value for this field is -.99. " DATA_TYPE = ASCII_REAL START_BYTE = 75 BYTES = 4 FORMAT = "F4.2" MISSING_CONSTANT = -.99 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "B OVER C MODEL" DESCRIPTION = " Many pole determination methods are based on a tri-axial ellipsoid model with semi-axes a > b > c which rotates 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. When a non_ellipsoidal model is used, it is described in a note in the note column. The table is not a comprehensive list of asteroid shapes and albedo models, but includes models obtained as by-products of pole determinations only. The null value for this field is -.99. " DATA_TYPE = ASCII_REAL START_BYTE = 80 BYTES = 4 FORMAT = "F4.2" MISSING_CONSTANT = -.99 END_OBJECT = COLUMN OBJECT = COLUMN NAME = "REFERENCE ID" DESCRIPTION = " 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, which may be found in the SPINREF.TAB table. " DATA_TYPE = CHARACTER START_BYTE = 86 BYTES = 6 FORMAT = A6 END_OBJECT = COLUMN OBJECT = COLUMN NAME = NOTE DESCRIPTION = " The numbers in this column refer to the following notes. For further information, see the individual references. 1. Solution curve 2. Value given for a/b is lower limit. 3. Different spin axis solutions for different apparitions was interpreted as indicating a precessing motion. 4. Symmetric solution obtained, but quantitative specification is missing. 5. Consistency check of previous spin vector determinations. 6. Based on a radar experiment giving constraints on the aspect angle at the time of observation. 7. Based on two radar experiments giving an aspect circle at the time of observation. 8. Modelled as a cylinder with hemispherical ends. 9. Modelled as a cylinder cut out of a sphere. 10. Complex shape. 11. Modelled as a Jacobi ellipsoid. 12. Modelled as 8 octants of ellipsoids put together to form a continuous surface. 13. Modelled as an ellipsoid with a piece removed by a plane cut. 14. Modelled as an irregular polyhedron. 15. Modelled as a sphere with free albedo facets. 16. Results show that there are no significant albedo variations. 17. Modelled using a sherical harmonics expansion of the shape. 18. Albedo model with a single big spot. 19. Modelled as a sphere with two dark regions. 20. Speckle images show albedo variations. 21. Bi-axial ellipsoid (a/b = 1.15) with a flat region just off the South Pole. 22. Also presented in Ful+91. 23. Also presented in English in Lup+90. 24. Also presented in Mi+90c. 25. a/b is assumed value. 26. b/c is assumed value. 27. a/b is a mean value of two significantly different solutions. 28. b/c is a mean value of two significantly different solutions. 29. Sidereal period is a mean value of two significantly different solutions. 30. Also presented in Det+94. 31. Detailed model from spacecraft images. 32. Also presented in Mic94. " DATA_TYPE = CHARACTER START_BYTE = 94 BYTES = 10 FORMAT = A10 END_OBJECT = COLUMN END_OBJECT = TABLE END