Data Set Overview : This is a compilation of mean U-B and B-V color indices of asteroids. This data file was provided by E.F. Tedesco, MRC and is a *preliminary* version. The version actually published will include UBV observations published through 1994 and the individual, referenced and commented, observations from which the average value was obtained. This dataset presents Johnson system U-B and B-V colors (or colors transformable to them) for asteroids, obtained between 1951 and 1989 and published through mid-1990. In addition, it uses Ted Bowell's unpublished observations from the Lowell UBV Asteroid Survey. The 978 mean U-B color indices are derived from 3,476 U-B observations. The 1,020 mean B-V color indices are derived from 4,010 B-V observations. The details of this synthesis will be submitted for publication in the future. For additional information contact Ed Tedesco.   Parameters : The data are presented in one ASCII file, 'ubvavg.tab'. The file contains one entry for each asteroid, with fields for the following paramenters. Catalog number of the asteroid, provisional designation (for data published under the provisional designation only), and for both U-B and B-V the mean color index, the standard deviation of the mean color index, the number of observations used to compute the mean value, and the minimum, maximum, and mean phase angles of the asteroid in the set of observations used to compute the mean.   Processing : The U-B and B-V values presented here are the unweighted averages of color indices compiled from the published literature. The full dataset including the source data and references will be incorporated into the PDS when the compilation has been published, sometime in the future.   Data : The data are included in the ASCII data table 'ubvavg.tab'.   Media/Format : This dataset is released in the form of ASCII files which may be stored on disk or other magnetic media and which may be distributed by ftp, email, realtime access by remote login, or by whatever means is most convenient.

Review : This dataset underwent a formal external review on March 31, 1995.   Data Coverage and Quality : This dataset includes data published through mid-1990. The complete dataset including source data and references, which will be complete through 1994, will be released in the future.   Limitations : This dataset is a compilation of data taken from the published literature, as well as unpublished data from the Lowell UBV Asteroid Survey. It is a provisional data product and will be replaced with the complete product in the future.