Description of the ASTEROID LIGHTCURVE DERIVED DATA bundle V1.0 =============================================================== Bundle Generation Date: 2017-09-18 Peer Review: 2017b Asteroid Review, Wed May 31 00:00:00 MST 2017 Discipline node: Small Bodies Node Content description for the ASTEROID LIGHTCURVE DERIVED DATA bundle =================================================================== This is a compilation of published rotational parameters for lightcurve data on asteroids, based on the Warner et al. (2009) Asteroid Lightcurve Database. This is the version released on February 3, 2017. These data files are provided by Alan Harris (MoreData!), Brian D. Warner (Palmer Divide Observatory/MoreData!), and Petr Pravec, (Astronomical Institute, Czech Republic). The compilation is originally based on that published in Lagerkvist et al. (1989). Parameters ========== The data files included are listed here with a description of their contents. lcsummary.tab - The summary file includes one entry for each asteroid for which lightcurve observations have been made. Each entry gives the following parameters: rotation period; minimum and maximum amplitude of lightcurve; reliability code; and a flag for binarity. These parameters are selected as the best values known from the published literature. lcdetails.tab - The details file includes one entry for each publication of asteroid lightcurve results, with the same parameters as in the summary file but extracted from the individual publications. There is a reference code referring to the publications list (lc_references.tab). lc_binary.tab - A list of asteroids known or suspected to be binary, along with the reported primary and secondary periods and amplitudes. Primary and secondary periods correspond with the rotation period of the primary and the orbital period of the binary. Note that not all binaries listed are based on lightcurve studies, the list also includes adaptive optics and radar studies. An independent compilation of information on binary asteroids may be found in another PDS data set, the Binary Minor Planets Summary, EAR-A-COMPIL-5-BINMP. lc_npa.tab - A list of asteroids for which non-principal-axis (NPA) data have been reported, along with the reported primary and secondary periods and amplitudes. lc_references.tab - This file includes the complete citation for each reference cited in the data files. It also contains the BibCode of the reference. lc_spinaxis.tab - A list of asteroids for which spin axis determinations have been published. Includes published pole solutions plus a synthesis entry for each asteroid. Amplitudes quoted in these files are the difference between maximum and minimum light, with some accounting for noise in the data. Note that for the release of spring 2016 (V16.0) the formats of the summary, details, and binary files have changed with the addition of some columns of supporting information. See aareadme.asc in the document directory for details. Documentation ========== The file readme.asc, included in the document directory, contains a description of the data files and how they were compiled. The readme file was released with the full distribution of the Asteroid Lightcurve Database, including a few files not included in the PDS archive. The Ambiguous Periods file was removed by the 2008 PDS review panel on the grounds that it is of marginal utility. The detailed binary asteroid files maintained by Petr Pravec, although part of the Asteroid Lightcurve Database, have not been supplied to us and are thus not included. Since the data files have been reformatted to conform to PDS requirements, the byte counts in the detailed format descriptions in readme.asc may not match the files. The order of the columns has not been changed. The file readme.asc has not been edited by PDS except to adjust the format to conform to PDS requirements. In addition, a frequency-diameter plot of all the LCDB asteroids, lcdb_frequency_diameter_plot.pdf, has been included in the document directory. Modification History ==================== The lc data set was first introduced into PDS at the April 1994 asteroid datasets review. It was subsequently updated at the March 1996 review, the April 1999 review, the May 2002 review, the May 2004 review, and the June 2005 review. Updates consist of adding information published or released since the last update. At the May 2002 review of version 5.0, it was decided to separate the reference number listings, which were becoming long, from the main data table. The lccross.tab file was created to provide the cross-listing information between objects and references. The reference list in the main data file was replaced with a single number indicating the total number of references for each object. For the May 2007 review, the compilers of this data set (Harris, Warner, and Pravec) had loaded the data into a database and were able to provide the data files in a slightly updated and more uniform format. The lcscross.tab crosslisting file is no longer needed, since each line in lcdetails.tab is tied to its appropriate reference through the lc_references.tab file. The entries in the other data files also each cite a specific reference in lc_references.tab. The data set was subsequently updated in 2008 with the addition of data published through February 2008. In the 2008 version the spin axis compilation was removed from the data set because it is a subset of the spin axis compilation of Kryszczynska which is included in a separate data set. The ambiguous periods compilation was also not included because reviewers considered it to have marginal value in the permanent archive. The data set has subsequently been updated in the same form in 2010, 2011, 2012, 2014, 2015, 2016, and 2017. In the version of 2011 and subsequent versions, the spinaxis file has been restored because it is more complete than the previously archived spin axis compilation. References ========== Lagerkvist, C.-I., A.W. Harris, and V. Zappala, Asteroid lightcurve parameters. In 'Asteroids II', Binzel, R.P., T. Gehrels, and M.S. Matthews, Eds. (University of Arizona Press: Tucson) p. 1162, 1989. Warner, B.D., A.W. Harris, and P. Pravec, The asteroid lightcurve database, Icarus 202, 134-146, doi:10.1016/j.icarus.2009.02.003, 2009. Known issues or problems with the data ====================================== The confidence level of each entry in the data set is indicated by a quality code U. This quality code is described in the associated data label, 'lc_summary.lbl'. For further information the user is referred to the file readme.asc in the document directory. As noted in Warner et al. (2009, Icarus 202, 134-146), only those objects with a U code of 2- or greater in the LC_SUMMARY file, i.e., U = 2-, 2, 2+, 3-, or 3, should be used for rotational rate studies and, unless there is a specific reason otherwise, the summary line period should be used instead of one of the periods in the details table. The U code describes the authors' assessment of the quality of the period solution, and takes the following values: 0 - Result later proven incorrect. This appears only on records of individual observations. 1 - Result based on fragmentary lightcurve(s), may be completely wrong. 2 - Result based on less than full coverage, so that the period may be wrong by 30 percent or so. Also, a quality of 2 is used to note results where an ambiguity exists as to the number of extrema per cycle or the number of elapsed cycles between lightcurves. Hence the result may be wrong by an integer ratio. 3 - Denotes a secure result with no ambiguity and full lightcurve coverage. 4 - In addition to full coverage, denotes that a pole position is reported. In many cases, the numerical quality code may be followed by a plus or minus sign, indicating that the reliability is judged somewhat better (+) or worse (-) than implied by an un-signed number alone. This refinement in scale has been only recently added, and not yet retroactively, so many entries don't have signs, even in some cases where they would be appropriate. See readme.asc in the document directory for additional information about the meaning of the plus or minus signs.