Description of the SDSS-BASED ASTEROID TAXONOMY bundle V1.0 =========================================================== Bundle Generation Date: 2020-02-28 Peer Review: 2011 Asteroid Review, Tue May 31 00:00:00 MST 2011 Discipline node: Small Bodies Node Content description based on the data set catalog file description for the PDS3 version, EAR-A-I0035-5-SDSSTAX-V1.1 =================================================================================================================== Note: for PDS3 data sets migrated to PDS4, the following text is taken verbatim from the data set description and confidence level note of the PDS3 data set catalog file. In these cases, some details may not be correct as a description of the PDS4 bundle. The Sloan Digital Sky Survey Moving Object Catalog (SDSS-MOC) is a large data set that provides five-filter magnitudes and astrometric information for all moving objects identified in the SDSS images. Its 4th release contains 471,569 detections prior to March 2007, where 220,101 are linked to 104,449 unique objects (Izevic et al. 2010). This actual data set is the result of the taxonomic classification for the SDSS-MOC asteroid observations. The asteroid observations are classified into nine classes: Vp, Op, Qp, Sp, Ap, Lp, Dp, Xp, and Cp, all related to the classes and complexes of Bus taxonomy (Bus & Binzel, 2002b). Furthermore the probability for each observation to belong each class are also computed. After this, the taxonomic classifications for each observation are collapsed into a single classification for each asteroid. Asteroids and observations were allowed to be assigned to more than one class. Further information about the method, the defining limits for each class and the classification algorithm can be found in Carvano et al. (2010). The data set is composed of three tables: The SDSS Taxonomy Observation Table (107,467 records) containing the taxonomic types for the multiple SDSS-MOC observations of each asteroid. This file also contains the classification probability score and the logarithmic reflectance values. The SDSS Taxonomy Asteroid Table (63468 records) containing the SDSS observed asteroids with their respective taxonomic type. This file also contains the probability scores, typical observations, binary flags and supporting astrometric informations. The SDSS Taxonomy Templates (9 records) is the table containing templates representing each taxonomic type. Each template has its modal logarithmic reflectance value and its color ranges used on the classification procedure. == Logarithmic Reflectances == Logarithmic reflectances (log reflectances) are directly proportional to calibrated magnitude colors, but their values are independent of reference reflectance, which reduces the influence of the normalization on asteroid spectra. Therefore log reflectances are not absolute values but a differential quantity relative to the reference filter. The calibrated magnitude colors are obtained by the difference of the SDSS magnitudes relative to a reference filter and subtracting it the solar colors, obtained from Izevic et al. (2001). Finally the log reflectances can be simply derived from Pogson equation, where log reflectance is -0.4*Cx + log(Rref), whereas magnitude color Cx = mx - mref - (mxsun - mrefsun). The uncertainties were calculated by propagation of the magnitude errors. The g' band is set as reference due to its band peak (0.47 micrometers) be located close to the standard reference wavelength position at 0.550 micrometers. == References == Bus, S.J. and R.P. Binzel, Phase II of the small main-belt asteroid spectroscopic survey: A feature-based taxonomy, Icarus 158, 146- 177, 2002. Carvano, J. M.; Hasselmann, P. H.; Lazzaro, D.; Mothe-Diniz, T. SDSS-based taxonomic classification and orbital distribution of main belt asteroids, Astronomy and Astrophysics, Volume 510, id.A43, DOI: 10.1051/0004-6361/200913322, 2010. Ivezic, Z., Juric, M., Lupton, R.H., Tabachnik, S., Quinn, T., and the SDSS Collaboration, SDSS Moving Object Catalog V3.0. EAR-A-I0035-3-SDSSMOC-V3.0. NASA Planetary Data System, 2010. Ivezic, Z. and 31 others, Solar System objects observed in the Sloan Digital Sky Survey commissioning data, AJ 122, 2749-2784, 2001. == Modification History == The data set was updated to version 1.1 in early 2012 to correct colunm name and descriptions in the file sdsstax_obs_table.lbl, changing REFLECTANCE_xxx to LOG_REFLECTANCE_xxx, and to add a description of the derivation of the log reflectances to the data set description. Typos and sentences were corrected, also some minor changes were made in the data set description to clarify the text. Known issues or problems with the data ====================================== All the photometric and astrometric data are provided by the SDSS MOVING OBJECT CATALOG V3.0 (Izevic et al. 2010), thus any information about the confidence level must be located there. The data was sampled before the classification procedure, which is represented by the binary flag at the colunm BAD. This quality flag is raised when one or more magnitudes had uncertainties above the 3rd quartile of the error distributions. The taxonomic classification for these observations and asteroids must be handled with caution. For further information about this quality flag, see Carvano et al. (2010). PDS3 Source =========== Version 1.0 of this bundle was migrated from version 1.1 of the PDS3 data set EAR-A-I0035-5-SDSSTAX-V1.1.