VEGA 1/2 MISCHA CD Version 1.1 Date 12. Aug. 1997 IWF Graz Magda Delva ============================================================================== DESCRIPTION OF THE CONTENTS OF THE SURVEY FILE FOR VEGA MAGNETIC FIELD CRUISE PHASE DATA IWF, GRAZ, June 1996 Magda Delva ********************************************************************** 1. ABSTRACT ----------- The SURVEY file of the magnetic field data, measured by the MISCHA - experiment on board of the Vega spacecraft, contains the following types of data: the position of the spacecraft in heliocentric (solar) ecliptic coordinates (H.SE), magnetic field data in a coordinate system centered at the spacecraft with x - axis to the sun and (x,y) - plane in its orbital plane (i.e. almost equal to the ecliptic). In addition, quality flags give information about missing or bad data. ********************************************************************** WARNING! ******** It is strongly recommended to control the value of the flag Q.ATT before any SE magnetic field data are used: - if Q.ATT= 1, the SC is only one-axis stabilized (Bx in direction to the SUN; THE SC CAN ROTATE FREELY AROUND THIS AXIS, THE DIRECTION OF THE BY AND BZ COMPONENTS IS NOT KNOWN AND CAN VARY LARGELY, ONLY SQRT(BY**2 + BZ**2) IS MEANINGFULL AND GIVES THE FIELD PERPENDICULAR TO THE SE X-AXIS!!!!! - if Q.ATT=-1, NO SE data are available (all values are flagged); - if Q.ATT= 0, the SC is three-axis stabilized and all three SE components of the field are correct in direction. FOR VEGA-1: Time-interval: Q.ATT 22 DEC 84 13:34 - 03 FEB 85 08:19 1 03 FEB 85 08:22 - 18 FEB 85 09:38 -1 18 FEB 85 09:41 - 20 MAY 85 09:39 1 20 MAY 85 09:41 - 06 JUL 85 08:19 0 06 JUL 85 08:22 - 14 AUG 85 09:39 -1 14 AUG 85 09:41 - 28 JUN 86 23:59 0 29 JUN 86 00:02 - 31-DEC-86 06:05 -1 FOR VEGA-2: Time-interval: Q.ATT 28 DEC 84 08:09 - 04 JAN 85 09:38 -1 04 JAN 85 09:41 - 16 MAY 85 04:14 1 30 JUN 85 05:14 - 22 JUL 85 08:19 0 22 JUL 85 08:22 - 08 AUG 85 02:49 -1 10 AUG 85 05:51 - 05 AUG 86 10:00 0 05 AUG 86 10:38 - 11 OCT 86 05:35 -1 ********************************************************************** H.SE - coordinate system: Heliocentric ecliptic coord. system: positions of the SC are given in this co. system: x-axis to equinox 1950., z-axis to ecliptic northpole, (x,y)-plane is the ecliptic plane. SE - coordinate system: Solar Ecliptic system: spacecraft-centered, x-axis to sun, (xy)-plane is orbital plane of spacecraft, i.e. nearly equal to the ecliptic plane, z-axis nearly to ecliptic pole. 2. DESCRIPTION OF THE HEADER - FILE ----------------------------------- name of header and data files: S1CT1SE date files created: 13-SEP-95 record length of data file, in bytes: 56 number of columns: 13 number of rows: 289467 flag for missing data: 0.10E+33 # name units source type loc ---------------------------------------------------------------------------- 001 UT s VEGA-1 MISCHA T 0 =Time variable in seconds after 1 Jan. 1965 002 X H.SE 1950 km VEGA-1 MISCHA R 8 003 Y H.SE 1950 km VEGA-1 MISCHA R 12 004 Z H.SE 1950 km VEGA-1 MISCHA R 16 005 R H.SE 1950 km VEGA-1 MISCHA R 20 =Heliocentric rectangular ecliptic coord. of spacecraft, x-axis to vernal equinox, equinox 1950.0. 006 BX SE nT VEGA-1 MISCHA R 24 007 BY SE nT VEGA-1 MISCHA R 28 008 BZ SE nT VEGA-1 MISCHA R 32 009 BT SE nT VEGA-1 MISCHA R 36 =Magn. field comp. in spacecraft centered Solar Ecliptic system (x-axis to sun, y-axis opposite to SC-velocity, z approx. to ecliptic northpole) 010 Q.OFFSET VEGA-1 MISCHA R 40 =Quality flag for offset: 0 : offset o.k., no problems -1 : no offset available, calculation impossible 1 : offset available, but value can have an error. 011 Q.POS VEGA-1 MISCHA R 44 =Quality flag for position: 0 : position is o.k. -1 : no position available. 012 Q.ATT VEGA-1 MISCHA R 48 =Quality flag for attitude of spacecraft, i.e. orientation of original raw data (PSSO) coordinate system is available or not: 0 : three-axis-stabilisation and a full matrix A to transform from PSSO to SE is known -1 : no information about spacecraft orientation, no matrix A 1 : one-axis-orientation, only angle A0 between x-axis and direction to the sun is known, the SC can rotate FREELY around the x-axis. 013 Q.FLAG VEGA-1 MISCHA R 52 =Quality flag for glitches: 0 : data are o.k. 1 : here is a glitche. NOTES: Start time = 22-DEC-84 13:34:22.000 End time = 31-DEC-86 06:05:09.000 ABSTRACT ORBIT= OWNER= Magda Delva MODE = CAL + ROT RESOL= 150 SEC =type of data: calibrated and rotated data, resolution 150 seconds. COORDINATE SYSTEM= PSSO =original coord. system of RAW data OFFSET= V1:-10.,-5.,40., V2:-11.,-10., =offset substracted from the original data to give PSSO data on the file. BPSSO = BORIGINAL - OFFSET =BPSSO = BX-OX etc., after offset correction. SOURCE FILES: PSSO-file: use$:b01ct1 OFFSET-file: dua0:[imf.mischa.delva]b01offset POS-file: dua0:[RADITSCH.DATEN]VEGAPOS.DAT Edited from the file: b01ct1master =Internal information about origin of additional data for generation of masterfile. Done by M. DELVA date: 95-09-13 END