File: M10MAGHR_FMT.txt Version: NSSDC 12/22/98 JFC ------------------------------------------------------------------------------ Hourly Interplanetary Magnetic Field Data from Mariner 10 for 1973 - 1974 Principal Investigator: Professor Norman F. Ness, Bartol Research Institute, University of Delaware, Newark, Delaware, U.S.A. NSSDC Data Set ID: 73-085A-04P (source data in VMS binary format) Date Coverage: 1973-11-03 to 1974-09-18 Description: This data set consists of files M10MAGyy.asc (yy = 73, 74) for years 1973 and 1974 of the Mariner 10 interplanetary magnetic field measurements. These data are in ASCII format and were extracted with the FORTRAN code M10MAGHR.for from VMS binary data in NSSDC Data Set 73-085A-04P; the format of this original data set on magnetic tape is described below. The word sequence of the ASCII version is similar to that of the binary format except that items 1, 2, 6, 16 - 27, and 30 (see original document below) have been excluded. Users needing the standard deviations (items 16 - 27) for the directional components should refer to the original binary data set; the other excluded items (1, 2, 6, and 30) are not needed. Data Format: The following write statement in M10MAGHR.for specifies the output formatting for the M10MAGyy.asc files: WRITE(20,150) IYR,IDAY,IHR,RAD,NCARR,HLON,HLAT,ESSANG,BXSEQ, * BYSEQ,BZSEQ,BMAG,ELANG,AZANG 150 FORMAT(1X,I4,1X,I3,1X,I2,1X,1PE11.3,1X,I4,1X,9(1PE11.3)) The output parameters are defined as follows: IYR YEAR OF THE DATA INTERVAL (LAST TWO DIGITS ONLY). IDAY DAY OF THE DATA INTERVAL FROM THE FIRST DAY OF THE ABOVE YEAR; JAN. 1 = DAY 1 ! IHR HOUR OF THE DAY OF THE DATA INTERVAL. RAD SPACECRAFT HELIOCENTRIC DISTANCE IN ASTRONOMICAL UNITS. NCARR CARRINGTON ROTATION NUMBER AS SEEN BY AN EARTH BASED OBSERVER AT THE START OF THE DATA INTERVAL HLON CARRINGTON LONGITUDE OF THE SUBSPACECRAFT POINT ON THE SUN AT THE START OF THE DATA INTERVAL, IN DEGREES (0-360). HLAT HELIOGRAPHIC LATITUDE OF THE SUBSPACECRAFT POINT AT THE START OF THE DATA INTERVAL IN DEGREES (+,-90). ESSANG EARTH-SUN-SPACECRAFT SEPARATION ANGLE IN DEGREES (0-360) MEASURED COUNTERCLOCKWISE FROM THE EARTH-SUN LINE LOOKING DOWN FROM THE NORTH. BXSEQ THE COMPONENT OF THE INTERPLANETARY MAGNETIC FIELD ALONG THE X AXIS IN THE SOLAR EQUATORIAL SYSTEM, POSITIVE TOWARD THE SUN (IN NANOTESLAS). (BEHANNON AND OTTENS,1976). BYSEQ SAME AS WORD 12 FOR THE Y AXIS COMPONENT. BZSEQ SAME AS WORD 12 FOR THE Z AXIS COMPONENT. BMAG THE TOTAL MAGNITUDE OF THE MAGNETIC FIELD VECTOR (IN NANO- TESLAS). ELANG THE ELEVATION ANGLE ,THETA, OF THE MAGNETIC FIELD VECTOR IN THE SOLAR EQUATORIAL COORDINATE SYSTEM. AZANG THE AZIMUTH ANGLE, PHI, OF THE MAGNETIC FIELD VECTOR IN THE SOLAR EQUATORIAL COORDINATE SYSTEM. Source Data Set: The binary data file M10MAGHR.VMSBIN for this data set is not kept here but can be retrieved from anonymous@nssdca.gsfc.nasa.gov in directory [COHO.MARINER_10.MAG.HOUR] or from the following URL on the web: http://nssdca.gsfc.nasa.gov/htbin/htdir/anon_dir/coho/mariner_10/mag/hour/ The document below refers to the original data file on magnetic tape as submitted to NSSDC in IBM binary format. The word structure of the binary file M10MAGHR.VMSBIN remains the same in the on-line data set version but the binary format has been converted to VMS binary. -------------------------------------------------------------------------- MARINER 10 73-085A-04P THIS TAPE CONTAINS ONE-HOUR AVERAGES OF THE INTERPLANETARY MAGNETIC FIELD OBTAINED BY MARINER 10 (N. NESS, PRINCIPAL INVESTIGATOR). THE DATA WERE DERIVED FROM DATA SET 73-085A-04C WHICH WAS PREPARED AND PROVIDED BY K. BEHANNON. THE DATA HAVE BEEN CONVERTED TO SOLAR EQUATORIAL X,Y,AND Z COMPONENTS AND THE CARRINGTON ROTATION NUMBER AND LONGITUDE AND EARTH-SUN-SPACECRAFT ANGLE HAVE BEEN ADDED BY NSSDC. THE DATA HAVE BEEN PUT IN THE STANDARD FORMAT COMPATIBLE WITH OTHER SOLAR WIND DATA IN THE DEEP SPACE MISSION SOLAR WIND DATA SERIES (PRODUCED BY NSSDC). THE DATA COVER THE PERIOD 11/03/73 TO 09/18/74. DETAILS OF THE TAPE: - FILE 1: THIS DOCUMENTATION (ASCII 8-BIT CHARACTERS,80 PER RECORD) - FILE 2: DATA FILE - 1600 BPI - 9 TRACK - IBM 360 BINARY (32 BITS) - FOR THE DATA FILE, ALL WORDS ARE SINGLE PRECISION FLOATING POINT, EXCEPT WORD 1 WHICH IS IN CHARACTERS (A4 FORMAT). - EACH LOGICAL RECORD CONTAINS 30 WORDS (120 BYTES). - THE BLOCKSIZE IS 100 LOGICAL RECORDS (12,000 BYTES). - ALL DATA ARE ONE HOUR AVERAGES AND THE TIME TAGS REFER TO THE BEGINNING OF THE DATA INTERVAL IN SPACECRAFT EVENT TIME. THE DATA WORDS REPRESENT THE FOLLOWING PARAMETERS: WORD NUMBER: 1. SPACECRAFT IDENTIFICATION: M10 FOR MARINER 10 2. DATA CODE: 2 MEANS MAGNETOMETER DATA ONLY. 3. YEAR OF THE DATA INTERVAL (LAST TWO DIGITS ONLY). 4. DAY OF THE DATA INTERVAL FROM THE FIRST DAY OF THE ABOVE YEAR; JAN. 1 = DAY 1 ! 5. HOUR OF THE DAY OF THE DATA INTERVAL. 6. CUMMULATIVE DAY AND FRACTIONAL DAY SINCE JANUARY 1, 1972. EXAMPLE: 1200 HR SPACECRAFT TIME JAN. 1, 1972 = DAY 1.5. 7. SPACECRAFT HELIOCENTRIC DISTANCE IN ASTRONOMICAL UNITS. 8. CARRINGTON ROTATION NUMBER AS SEEN BY AN EARTH BASED OBSERVER AT THE START OF THE DATA INTERVAL 9. CARRINGTON LONGITUDE OF THE SUBSPACECRAFT POINT ON THE SUN AT THE START OF THE DATA INTERVAL, IN DEGREES (0-360). 10.HELIOGRAPHIC LATITUDE OF THE SUBSPACECRAFT POINT AT THE START OF THE DATA INTERVAL IN DEGREES (+,-90). 11.EARTH-SUN-SPACECRAFT SEPARATION ANGLE IN DEGREES (0-360) MEASURED COUNTERCLOCKWISE FROM THE EARTH-SUN LINE LOOKING DOWN FROM THE NORTH. 12.BXSEQ, THE COMPONENT OF THE INTERPLANETARY MAGNETIC FIELD ALONG THE X AXIS IN THE SOLAR EQUATORIAL SYSTEM, POSITIVE TOWARD THE SUN (IN NANOTESLAS). (BEHANNON AND OTTENS,1976). 13.BYSEQ,SAME AS WORD 12 FOR THE Y AXIS COMPONENT. 14.BZSEQ, SAME AS WORD 12 FOR THE Z AXIS COMPONENT. 15.THE TOTAL MAGNITUDE OF THE MAGNETIC FIELD VECTOR (IN NANO- TESLAS). 16.THE RMS DEVIATION OF BXSEQ (IN NANOTESLAS). (BEHANNON AND OTTENS, 1976). 17.THE RMS DEVIATION OF BYSEQ (IN NANOTESLAS). 18.THE RMS DEVIATION OF BZSEQ (IN NANOTESLAS). 19.THE RMS DEVIATION OF THE FIELD MAGNITUDE (IN NANOTESLAS). 20. THROUGH 27. RESERVED FOR PLASMA DATA. SET TO ZERO IN THIS DATASET. 28.THE ELEVATION ANGLE ,THETA, OF THE MAGNETIC FIELD VECTOR IN THE SOLAR EQUATORIAL COORDINATE SYSTEM. 29.THE AZIMUTH ANGLE, PHI, OF THE MAGNETIC FIELD VECTOR IN THE SOLAR EQUATORIAL COORDINATE SYSTEM. 30.THE CUMMULATIVE WORD COUNT FOR THE FIRST WORD OF THE CURRENT LOGICAL RECORD FROM THE FIRST WORD OF THE DATA FILE. REFERENCES: 1. BEHANNON, K. W., OBSERVATIONS OF THE INTERPLANETARY MAGNETIC FIELD BETWEEN 0.46 AND 1 AU BY THE MARINER 10 SPACECRAFT, NASA/GSFC X-692-76-2, JANUARY, 1976. 2. BEHANNON, K. W. AND F. W. OTTENS, MARINER 10 INTERPLANETARY MAGNETIC FIELD MEASUREMENTS NOVEMBER 1973 - MARCH 1974, NASA/GSFC X-692-76-208, SEPTEMBER, 1976. END OF DOCUMENTATION.