Data Set Overview : This data set contains the polarimetric results reported to the International Halley Watch (IHW) Photometry and Polarimetry Network (PPN) by the various participating observers. Only linear polarizations are reported. Both standard and non-standard broadband and narrowband filters were employed. A total of 752 observations are included spanning the period 13 September 1985 to 17 May 1986.  Modification History : The first version of this data set contained 182 sets of individual observation files. Each file contained the results from one observer during one night. For each such file there was a PDS label file, a FITS table header file detached from the data, and the FITS table data segment.  PDS personnel made the following chages to create version 2:  o PDS labels were completely rewritten. All comments, history notes and significant keywords from the FITS headers were either included as PDS keywords or documented in the DESCRIPTION section for each file. The FITS headers were then discarded.  o Observing times in the observation tables, originally stated as day number and fraction, were converted to the ISO standard time format (yyyy-mm-ddThh:mm:ss). Day fractions were supplied with anywhere from 0 to 5 significant digits. In an attempt to preserve the significant digits in the ISO format, the minutes or second were rounded ar truncated to apporpriate values for the number of digits in the fraction:  Digits Rounded to Nearest 0 day 1 (not encountered) 2 15 minutes 3 1 minute 4 10 seconds 5 1 second  o The 'all.tab' file was created by adding the observatory, telescope, observer and file name to the records in each individual table, and concatenating the results into a single file. This file was then sorted on the UTC field at the beginning of each record.  o All reported errata were corrected.  27 June 2006, A.C.Raugh

Overview : Observers wre asked to submit error bars with their data, and most did. The errors are reported as separate columns in the data tables.