PVO Ion Mass Spectrometer high-resolution data are stored in single-orbit ASCII files. All of the data files have the same internal structure, which is described by the single format file OIMSDATA.FMT. File structure characteristics which may vary from file to file (# of records, start/stop time, etc.) are described in the individual PDS label files (*.LBL). Columns in all data files: ======================================================= name type description ------------------------------------------------------- PVO TIME char Date and time in format YYDOY FSEC, where YY is the year, DOY is the day-of-year & FSEC is the decimal second-of-day DWELL int Dwell time (time interval between samples, msec) DWELL = (TIME - UT)*1000/(n-1) BITS int Telemetry bit rate LAT float Venusian Latitude LON float Venusian Longitude ALT float Altitude SZA float Solar Zenith Angle SHA float Solar Hour Angle
MASS1 int Mass of Sample 1 DEN1 float Number density of Sample 1 MASS2 int Mass of Sample 2 DEN2 float Number density of Sample 2 . . . . . . . . . MASS55 int Mass of Sample 55 DEN55 float Number density of Sample 55 The values 999 and 9.9999e+04 are the missing data values for mass and density respectively. The value 99999.999 is the missing data value for the second-of-day part of the time column. Negative values in a density column indicate flagged (unreliable) data values. Data Files (.TAB extension) The high-resolution data files on this disk are ASCII table files, each having 118 columns and record length 953 bytes. Information about the individual files (number of records, start and stop times, etc.) can be obtained from the PDS label file accompanying each *.TAB file. This label file has the same filename as the data file but with .TAB replaced by .LBL. List of data files: ============================================================================ Name Records Cols Len Start Stop ---------------------------------------------------------------------------- ORB1711 144 118 953 1983-08-13T00:37:47.927Z 1983-08-13T01:00:19.427Z ORB1743 301 118 953 1983-09-14T00:36:54.033Z 1983-09-14T01:08:55.047Z ORB1750 311 118 953 1983-09-21T00:36:57.866Z 1983-09-21T01:09:30.880Z ORB1757 283 118 953 1983-09-28T00:36:50.565Z 1983-09-28T01:06:27.577Z ORB1771 31 118 953 1983-10-12T00:37:09.433Z 1983-10-12T00:40:24.434Z ORB1778 313 118 953 1983-10-19T00:37:18.546Z 1983-10-19T01:10:16.559Z ORB1785 149 118 953 1983-10-26T00:31:36.741Z 1983-10-26T00:54:55.491Z ORB1792 149 118 953 1983-11-02T00:30:29.397Z 1983-11-02T00:54:07.158Z ORB1796 154 118 953 1983-11-06T00:29:25.165Z 1983-11-06T00:53:31.166Z ORB1799 158 118 953 1983-11-09T00:28:10.354Z 1983-11-09T00:52:53.869Z Catalog Files (.CAT extension) Catalog data, which includes instrument, dataset, mission and spacecraft descriptions, can be found in the *.CAT files in the CATALOG directory on this disk.