C----------------------------------------------------------------------- SUBROUTINE GIODAT(TUTC,PVG,PVH,PVE,PVS,IERR) C------------------------------------------------- C S.J ISSUE 04 - 14.01.85 C------------------------ C ************ SUBROUTINE IDENTIFICATION ************ * * * GIODAT IS AN INTERFACE ROUTINE TO THE EXPERIMENTER SUPPORT DATA * * FILE ON LOGICAL UNIT 7 WHICH CONTAINS POSITION DATA FOR THE * * GIOTTO PROBE, HALLEYS COMET, THE EARTH AND THE SUN GIVEN IN THE * * BARYCENTRIC REFERENCE FRAME OF 1950 ( UNITS = KM ) * * THE APPROXIMATE VELOCITIES FOR THE FOUR BODIES WILL BE DERIVED * * FROM THE POSITION DATA AND GIVEN IN KM/S. * * * ************************************************************************ * * ************ VARIABLE IDENTIFICATIONS ************* * * ***** INPUT VARIABLES ( ARGUMENT LIST ) *** * * * TUTC - UNIVERSAL COORDINATED TIME * * * ***** OUTPUT VARIABLES ( ARGUMENT LIST ) *** * * * PVG(1-3) - POSITION OF THE GIOTTO PROBE AT TIME TUTC * * PVG(4-6) - VELOCITY OF THE GIOTTO PROBE AT TIME TUTC * * PVH(1-3) * * PVH(4-6) - DITTO FOR HALLEYS COMET * * PVE(1-3) * * PVE(4-6) - DITTO FOR THE EARTH * * PVS(1-3) * * PVS(4-6) - DITTO FOR THE SUN * * IERR - ERROR CODE * * =0 : NO ERROR * * =1 : TUTC TOO EARLY * * =2 : TUTC TOO LATE * * * ***** LOCAL VARIABLES *** * * * ET - MODIFIED JULIAN DAY ( 1950.0 ) * * PGI(3,3) - TO STORE POSITION DATA FOR THREE SAMPLES FOR THE * * GIOTTO PROBE. USED IN THE QUADRATIC INTERPOLATION * * PHI(3,3) - DITTO FOR HALLEYS COMET * * PEI(3,3) - DITTO FOR THE EARTH * * PSI(3,3) - DITTO FOR THE SUN * * T(3) - TO STORE REFERENCE TIME T0 FOR THE INTERPOLATION. * * SKIP(3) - USED FOR SKIPPING RECORDS ON THE DATA FILE * * * ***** CONSTANT IDENTIFICATION *** * * * HSEC - (STEP SIZE)*86400 * * LUN - LOGICAL UNIT NUMBER OF FILE/TAPE CONTAINING * * THE POSITION DATA. * * STPUTC - STEP IN UTC AT TIME SUTC * * * ***** TEMPORARY VARIABLES *** * * * (1) * * TMP(1) - 0.5*(P-1)*(P-2) * * TMP(2) - P*(P-2) * * TMP(3) - 0.5*P*(P-1) * * (2) * * TMP(1) - (P-1.5)/HSEC * * TMP(2) - (2*P-2)/HSEC * * TMP(3) - (P-0.5)/HSEC * * WHERE ET(P) IS THE EPOCH FOR WHICH THE POSITIONS ARE REQUIRED. * * ( RANGE OF P : 0:2 ) * * * ************************************************************************ * * ************ TYPE DECLARATION AND STORAGE ALLOCATION ************ * * IMPLICIT REAL*8(A-H,O-Z) LOGICAL FIRST CHARACTER*1 SKIP(3) DIMENSION PVG(6),PVH(6),PVE(6),PVS(6),PGI(3,3), & PHI(3,3),PEI(3,3),PSI(3,3),T(3),TMP(3) DATA FIRST/.TRUE./ DATA LUN/7/ * * ************************************************************************ * * ************ INITIALISE AND VERIFY INPUT DATA ***BLOCK0000 * * IERR=0 C IF FIRST CALL READ CONTROL RECORD AND SET CONSTANTS IF(FIRST)THEN READ(LUN,10) IYGEN,MOGEN,DGEN,NS,NR,ET1,ET2,SUTC,ETUTC1,ETUTC2 10 FORMAT(2I5,D16.10,2I5,/,5D16.10) C DETERMINE STEP IN UTC AT TIME SUTC STPUTC=ETUTC2-ETUTC1 C DETERMINE STEP SIZE H=(ET2-ET1)/(DFLOAT(NR)-1.D0) HSEC=H*86400.D0 FIRST=.FALSE. ENDIF C DETERMINE ET ( MODIFIED JULIAN DAY ) ET=TUTC+ETUTC1 IF(ET.GE.SUTC)ET=ET+STPUTC C VERIFY EPOCH ON FILE IF(ET.LT.ET1-1.D-4)GOTO 910 IF(ET.GT.ET2+1.D-4)GOTO 920 DO 20 I=1,6 PVG(I)=0.D0 PVH(I)=0.D0 PVE(I)=0.D0 PVS(I)=0.D0 20 CONTINUE * * ************************************************************************ * * ******* DETERMINE THE POSITION VECTORS FOR EPOCH ET **BLOCK0100 * * C FIND RECORD NUMBER IREC=DINT((ET-ET1)/H)+1 110 CONTINUE C POSITION THE T0 SAMPLE TO ENSURE T1 AND T2 AVAILABLE IF(NR-IREC.LT.2)THEN IREC=IREC-1 GOTO 110 ENDIF IF(FIRST)THEN IF(IREC.EQ.1)GOTO 135 DO 130 I=1,IREC-1 READ(LUN,120)SKIP 120 FORMAT(A1) 130 CONTINUE GOTO 135 ENDIF IDIF=IREC-IRECOL-1 IF(IDIF.EQ.0)GOTO 135 ISKP=ABS(IDIF) IF(IDIF.LT.0)THEN DO 131 I=1,ISKP*3 BACKSPACE LUN 131 CONTINUE ELSE DO 132 I=1,ISKP READ(LUN,120)SKIP 132 CONTINUE ENDIF 135 CONTINUE IRECOL=IREC+2 DO 150 I=1,3 READ(LUN,140)T(I),(PGI(I,J),J=1,3),(PHI(I,J),J=1,3), & (PEI(I,J),J=1,3),(PSI(I,J),J=1,3) 140 FORMAT(5D16.10) 150 CONTINUE * * * * ************************************************************************ * * ******* DETERMINE POSITIONS USING QUADRATIC INTERPOLATION **BLOCK0200 * * P=(ET-T(1))/H TMP(1)=0.5*(P-1.D0)*(P-2.D0) TMP(2)=P*(2.D0-P) TMP(3)=0.5D0*P*(P-1.D0) DO 220 I=1,3 DO 210 J=1,3 PVG(I)=PVG(I)+PGI(J,I)*TMP(J) PVH(I)=PVH(I)+PHI(J,I)*TMP(J) PVE(I)=PVE(I)+PEI(J,I)*TMP(J) PVS(I)=PVS(I)+PSI(J,I)*TMP(J) 210 CONTINUE 220 CONTINUE * * ************************************************************************ * * ******* DETERMINE VELOCITIES FROM DERIVATIVES OF POSITIONS **BLOCK0300 * * TMP(1)=(P-1.5D0)/HSEC TMP(2)=(2.D0-2.D0*P)/HSEC TMP(3)=(P-0.5D0)/HSEC DO 320 I=1,3 I1=I+3 DO 310 J=1,3 PVG(I1)=PVG(I1)+PGI(J,I)*TMP(J) PVH(I1)=PVH(I1)+PHI(J,I)*TMP(J) PVE(I1)=PVE(I1)+PEI(J,I)*TMP(J) PVS(I1)=PVS(I1)+PSI(J,I)*TMP(J) 310 CONTINUE 320 CONTINUE * * ************************************************************************ * * ************ ERROR MESSAGE BLOCK ***BLOCK0900 * * GOTO 1000 910 CONTINUE IERR=1 WRITE(6,911) 911 FORMAT(/' GIOPOS : ET TOO EARLY ') GOTO 1000 920 CONTINUE IERR=2 WRITE(6,921) 921 FORMAT(/' GIOPOS : ET TOO LATE ') 1000 CONTINUE RETURN END C----------------------------------------------------------------------