VEGA 1/2 MISCHA CD Version 1.1 Date 12. Aug. 1997 IWF Graz Magda Delva ============================================================================== DESCRIPTION OF THE CONTENTS OF THE MASTERFILE FOR VEGA MAGNETIC FIELD FLY-BY PHASE DATA IWF, GRAZ, Jan. 1989 Magda Delva ***************************************************************** 1. ABSTRACT ----------- The masterfile of the magnetic field data, measured by the MISCHA - experiment on board of the Vega spacecraft, contains the following types of data: the magnetic field data, the position of the space- craft in heliocentric (solar) ecliptic coordinates and in heliographic co. from the prime meredian, information about the orientation of the spacecraft, magnetic field data after calibration and rotation to a coordinate system centered at the spacecraft with x - axis to the sun and (x,y) - plane in its orbital plane ( i.e. equal to the ecliptic). In addition, quality flags give information about missing or bad data. PSSO - coordinate system: PSuedo SOlar coordinate system: spacecraft centered, x-axis only approximately directed to the sun (slight deviation possible), z-axis only approximately to ecliptic pole and (xy)- plane approximately the ecliptic in case of three-axis-stabilisation; in case of one-axis stabilisation of spacecraft no information about z-axis. 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 eclipic plane, z-axis nearly to eclipic pole. H.SE - coordinate system: Heliocentric Solar Ecliptic sytem: (xy)-plane is the ecliptic, x-axis to vernal equinox 1950, z-axis to ecliptic pole 2. DESCRIPTION OF THE HEADER - FILE ----------------------------------- name of header and data files: V1FBT1SE date files created: 11-DEC-90 record length of data file, in bytes: 220 number of columns: 54 number of rows: 5262 flag for missing data: 0.10E+33 # name units source type loc --------------------------------------------------------------------------- 001 UT s VEGA-1 MISCHA T 0 =Time variable in seconds 002 BX PSSO nT VEGA-1 MISCHA R 8 003 BY PSSO nT VEGA-1 MISCHA R 12 004 BZ PSSO nT VEGA-1 MISCHA R 16 =Magnetic field components as measured by the spacecraft in Pseudo Solar coordinates (PSSO). 005 BT PSSO nT VEGA-1 MISCHA R 20 =Total value of the magnetic field, calc. from BX, BY, BZ (PSSO). 006 BU PSSO nT VEGA-1 MISCHA R 24 =Magn. field comp. in x-direction, at sensor more close to center of spacecraft, in PSSO coordinate system. 007 BUX PSSO nT VEGA-1 MISCHA R 28 =(BU - BX) in PSSO coordinates. 008 OX PSSO nT VEGA-1 MISCHA R 32 009 OY PSSO nT VEGA-1 MISCHA R 36 010 OZ PSSO nT VEGA-1 MISCHA R 40 011 OU PSSO nT VEGA-1 MISCHA R 44 =Offsets for PSSO components of magn. field, to be subtracted from data. 012 BX-OX nT VEGA-1 MISCHA R 48 013 BY-OY nT VEGA-1 MISCHA R 52 014 BZ-OZ nT VEGA-1 MISCHA R 56 =Offset-corrected magn. field components in PSSO system. 015 BT(NEW) nT VEGA-1 MISCHA R 60 =New total field, calculated from offset-corrected magn. field comp. 016 BU-OU nT VEGA-1 MISCHA R 64 =Offset-corrected magn. field BU-comp. 017 BUX(NEW) nT VEGA-1 MISCHA R 68 =(BU-OU) - (BX-OX) in PSSO coord., should be approximately zero, if calibration is good. 018 MV(BTNEW) nT VEGA-1 MISCHA R 72 019 SD(BTNEW) nT VEGA-1 MISCHA R 76 =Daily Mean Value, Standard Deviation of BT(NEW). 020 METHOD VEGA-1 MISCHA R 80 =Integer, describing the method used to calc. offsets: 0 : spinning session method 1 : Russel - method (set of linear equations) 2 : Hedgecock - method (min. covariance) -1 : no offset available. 021 X H.SE 1950 km VEGA-1 MISCHA R 84 022 Y H.SE 1950 km VEGA-1 MISCHA R 88 023 Z H.SE 1950 km VEGA-1 MISCHA R 92 =Heliocentric rectangular ecliptic coord. of spacecraft, x-axis to vernal equinox, equinox 1950.0. 024 R H.SE 1950 km VEGA-1 MISCHA R 96 025 ELONG1950 deg VEGA-1 MISCHA R 100 026 ELAT 1950 deg VEGA-1 MISCHA R 104 =Heliocentric polar ecliptic coord. of spacecraft, x-axis to vernal equinox, equinox 1950.0. 027 CARR.ROT. nr VEGA-1 MISCHA R 108 =Carrington rotation nr. as seen from the earth, corresponding to UT. 028 CARR.LONG deg VEGA-1 MISCHA R 112 029 CARR.LAT. deg VEGA-1 MISCHA R 116 =Heliographic polar coord., longitude measured from PRIME meredian on the sun, mean equinox of date. 030 A11(PSSO-SE) VEGA-1 MISCHA R 120 031 A12(PSSO-SE) VEGA-1 MISCHA R 124 032 A13(PSSO-SE) VEGA-1 MISCHA R 128 033 A21(PSSO-SE) VEGA-1 MISCHA R 132 034 A22(PSSO-SE) VEGA-1 MISCHA R 136 035 A23(PSSO-SE) VEGA-1 MISCHA R 140 036 A31(PSSO-SE) VEGA-1 MISCHA R 144 037 A32(PSSO-SE) VEGA-1 MISCHA R 148 038 A33(PSSO-SE) VEGA-1 MISCHA R 152 =Transformation-matrix (rotation) for PSSO magn. field comp. system to a Solar Ecliptic co. system, with center at spacecraft, x-axis to the sun: - in case of one-axis-stabilisation of the spacecraft, only one rotation around z-axis over angle A0 (see below), (xy)-plane is not necessary the orbital or ecliptic plane; - in case of three-axis-stabilisation of the spacecraft the new (xy)-plane is the orbital plane of the spacecraft (i.e. nearly the ecliptic). 039 A0(XPSSO-XSE deg VEGA-1 MISCHA R 156 =Angle betw. (PSSO) x-axis and (SE) x-axis (to sun), in case of one-axis-stabilisation of spacecraft given. In case of three axis- stabilisation, the angle is calculated: A0=arcos(A11) 040 A EULER deg VEGA-1 MISCHA R 160 041 B EULER deg VEGA-1 MISCHA R 164 042 G EULER deg VEGA-1 MISCHA R 168 =Eulerian angles Alfa=ATAN2(A31,-A32) (0,360 deg.), Beta=ATAN2(A13, A23) (-180,+180 deg.), Gamma=ATAN2(A23/cos(Beta),A33) (0,180 deg.) between (PSSO) and (SE) co. system, in case of three- axis-stabilisation of spacecraft, according to definition of Eulerian angles in Landau & Lifschitz, Vol. I. 043 BX SE nT VEGA-1 MISCHA R 172 044 BY SE nT VEGA-1 MISCHA R 176 045 BZ SE nT VEGA-1 MISCHA R 180 046 BT SE nT VEGA-1 MISCHA R 184 =Magn. field comp. in spacecraft centered Solar Ecliptic system (x-axis to sun), i.e. B(PSSO-Offset) rotated with matrix A. 047 CLOCK A. deg VEGA-1 MISCHA R 188 048 CONE A. deg VEGA-1 MISCHA R 192 =Clock angle (arctan(BZ/BY), (-180,+180) deg.), cone angle (arccos(BX/BT), (0,180) deg.) of the SE magnetic field vector 049 AZIM.(B) deg VEGA-1 MISCHA R 196 050 ELEV.(B) deg VEGA-1 MISCHA R 200 =Azimuth (ATAN2(BY,BX), (0,360) deg.), elevation (ATAN2(BZ,BX/(cos(Azimuth)), (-90,+90) deg.) of the SE magnetic field vector. 051 Q.OFFSET VEGA-1 MISCHA R 204 =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. 052 Q.POS VEGA-1 MISCHA R 208 =Quality flag for position: 0 : position is o.k. -1 : no position available. 053 Q.ATT VEGA-1 MISCHA R 212 =Quality flag for attitude of spacecraft, i.e. orientation of PSSO coordinate system: 0 : three-axis-stabilisation and a full matrix A is known -1 : no information about spacecraft orientation, no matrix A 1 : one-axis-orientation, one angle A0 is known. 054 Q.FLAG VEGA-1 MISCHA R 216 =Quality flag for glitches: 0 : data are o.k. 1 : here is a glitche. NOTES: Start time = 28-FEB-86 10:16:08.000 End time = 10-MAR-86 23:59:34.000 ABSTRACT ORBIT= OWNER= Magda Delva MODE = CAL + ROT RESOL= 150 SEC =type of data: calibrated nd rotated data, resolution 150 seconds. COORDINATE SYSTEM= PSSO =original coordinate system of data, before processing. 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: [VEGA.FLYBY]B01FBT1 OFFSET-file: B01FBT1OFF POS-file: [vega.position]veg1pos =Internal information about origin of additional data for generation of masterfile. END