Source Code
041360,000001: # Copyright: Public domain.
041361,000002: # Filename: LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc
041362,000003: # Purpose: A section of Luminary 1C, revision 131.
041363,000004: # It is part of the source code for the Lunar Module's (LM)
041364,000005: # Apollo Guidance Computer (AGC) for Apollo 13 and Apollo 14.
041365,000006: # This file is intended to be a faithful transcription, except
041366,000007: # that the code format has been changed to conform to the
041367,000008: # requirements of the yaYUL assembler rather than the
041368,000009: # original YUL assembler.
041369,000010: # Reference: pp. 983-986 of 1729.pdf.
041370,000011: # Contact: Ron Burkey <info@sandroid.org>.
041371,000012: # Website: www.ibiblio.org/apollo/index.html
041372,000013: # Mod history: 05/29/03 RSB. Began transcribing.
041373,000014: # 05/14/05 RSB Corrected website reference above.
041374,000015:
041375,000016: # Page 983
041376,000017: # NAME -- LSPOS -- LOCATE SUN AND MOON DATE -- 25 OCT 67
041377,000018: # MOD NO. 1
041378,000019: # MOD BY NEVILLE ASSEMBLY SUNDANCE
041379,000020:
041380,000021: # FUNCTIONAL DESCRIPTION
041381,000022:
041382,000023: # COMPUTES UNIT POSITION VECTOR OF THE SUN AND MOON IN THE BASIC REFERENCE SYSTEM. THE SUN VECTOR S IS
041383,000024: # LOCATED VIA TWO ANLES. THE FIRST ANGLE (OBLIQUITY) IS THE ANGLE BETWEEN THE EARTH EQUATOR AND THE ECLIPTIC. THE
041384,000025: # POSITION VECTOR OF THE SUN IS
041385,000026: # _
041386,000027: # S = (COS(LOS), COS(OBL)*SIN(LOS), SIN(OBL)*SIN(LOS)), WHERE
041387,000028:
041388,000029: # LOS = LOS +LOS *T-(C *SIN(2PI*T)/365.24 +C *COS(2PI*T)/365.24)
041389,000030: # 0 R 0 1
041390,000031: # LOS (RAD) IS THE LONGITUDE OF THE SUN FOR MIGNIGHT JUNE 30TH OF THE PARTICULAR YEAR.
041391,000032: # 0
041392,000033: # LOS (RAD/DAY) IS THE MEAN RATE FOR THE PARTICULAR YEAR.
041393,000034: # R
041394,000035:
041395,000036: # LOS AND LOS ARE STORED AS LOSC AND LOSR IN RATESP.
041396,000037: # 0 R
041397,000038: # COS(OBL) AND SIN(OBL) ARE STORED IN THE MATRIX KONMAT.
041398,000039:
041399,000040: # T, TIME MEASURED IN DAYS (24 HOURS) IS STORED IN TIMEP.
041400,000041:
041401,000042: # C AND C ARE FUDGE FACTORS TO MINIMIZE THE DEVIATION. THEY ARE STORED AS ONE CONSTANT (CMOD), SINCE
041402,000043: # 0 1 2 2 1/2
041403,000044: # C *SIN(X)+C *COS(X) CAN BE WRITTEN AS (C +C ) *SIN(X+PHI), WHERE PHI=ARCTAN(C /C ).
041404,000045: # 0 1 1 0
041405,000046:
041406,000047: # THE MOON IS LOCATED VIA FOUR ANGLES, THE FIRST IS THE OBLIQUITY. THE SECOND IS THE MEAN LONGITUDE OF THE MOON,
041407,000048: # MEASURED IN THE ECLIPTIC FROM THE MEAN EQUINOX TO THE MEAN ASCENDING NODE OF THE LUNAR ORBIT, AND THEN ALONG THE
041408,000049: # ORBIT. THE THIRD ANGLE IS THE ANGLE BETWEEN THE ECLIPTIC AND THE LUNAR ORBIT. THE FOURTH ANGLE IS THE LONGITUDE
041409,000050: # OF THE NODE OF THE MOON, MEASURED IN THE LUNAR ORBIT. LET THESE ANGLES BE OBL,LOM,IM, AND LON RESPECTIVELY.
041410,000051:
041411,000052: # THE SIMPLIFIED POSITION VECTOR OF THE MOON IS
041412,000053: # _
041413,000054: # M=(COS(LOM), COS(OBL)*SIN(LOM)-SIN(OBL)*SIN(IM)*SIN(LOM-LON), SIN(OBL)*SIN(LOM)+COS(OBL)*SIN(IM)*SIN(LOM-LON))
041414,000055:
041415,000056: # WHERE
041416,000057: # LOM=LOM +LOM *T-(A *SIN(2PI*T/27.5545)+A *COS(2PI*T/27.5545)+B *SIN(2PI*T/32)+B *COS(2PI*T/32)), AND
041417,000058: # 0 R 0 1 0 1
041418,000059: # LON=LON +LON
041419,000060: # 0 R
041420,000061: # A , A , B AND B ARE STORE AS AMOD AND BMOD (SEE DESCRIPTION OF CMOD, ABOVE). COS(OBL), SIN(OBL)*SIN(IM),
041421,000062: # 0 1 0 1
041422,000063: # SIN(OBL), AND COS(OBL)*SIN(IM) ARE STORED IN KONMAT AS K1, K2, K3, AND K4, RESPECTIVELY. LOM , LOM , LON , LON
041423,000064: # 0 R 0 R
041424,000065: # ARE STORED AS LOM0, LOMR, LON0, AND LONR IN RATESP.
041425,000066:
041426,000067: # THE THREE PHIS ARE STORED AS AARG, BARG, AND CARG(SUN). ALL CONSTANTS ARE UPDATED BY YEAR.
041427,000068:
041428,000069: # CALLING SEQUENCE
041429,000070: # Page 984
041430,000071: # CALL LSPOS. RETURN IS VIA CPRET.
041431,000072:
041432,000073: # ALARMS OR ABORTS
041433,000074: # NONE
041434,000075:
041435,000076: # ERASABLE INITIALIZATION REQUIRED
041436,000077: # TEPHEM -- TIME FROM MIGNIGHT 1 JULY PRECEDING THE LAUNCH TO THE TIME OF THE LAUNCH (WHEN THE AGC CLOCK WENT
041437,000078: # TO ZERO). TEPHEM IS TP WITH UNITS OF CENTI-SECONDS.
041438,000079:
041439,000080: # TIME2 AND TIME1 ARE IN MPAC AND MPAC +1 WHEN PROGRAM IS CALLED.
041440,000081:
041441,000082: # OUTPUT
041442,000083: # UNIT POSITIONAL VECTOR OF SUN IN VSUN. (SCALED B-1)
041443,000084: # UNIT POSITIONAL VECTOR OF MOON IN VMOON. (SCALED B-1)
041444,000085:
041445,000086: # SUBROUTINES USED
041446,000087: # NONE
041447,000088:
041448,000089: # DEBRIS
041449,000090: # CURRENT CORE SET, WORK AREA AND FREEFLAG
041450,000091:
041451,000092: 04,2773 BANK 04
041452,000093: 15,2000 SETLOC EPHEM
041453,000094: 15,2000 BANK
041454,000095:
041455,000096: 15,3647 E5,1714 EBANK= VSUN
041456,000097: 15,3647 COUNT* $$/EPHEM
041457,000098: 15,3647 15,3647 LUNPOS EQUALS LSPOS
041458,000099:
041459,000100: 15,3647 54201 LSPOS SETPD SR
041460,000101: 15,3650 00001 0
041461,000102: 15,3651 20617 14D # TP
041462,000103: 15,3652 56371 TAD DDV
041463,000104: 15,3653 01707 TEPHEM # TIME OF LAUNCH
041464,000105: 15,3654 12024 CSTODAY # 24 HOURS -- 8640000 CENTI-SECS/DAY B-33
041465,000106: 15,3655 00031 STORE TIMEP # T IN DAYS
041466,000107: 15,3656 77170 AXT,1 AXT,2
041467,000108: 15,3657 00000 0
041468,000109: 15,3660 00000 0
041469,000110: 15,3661 77614 CLEAR
041470,000111: 15,3662 00274 FREEFLAG # SWITCH BIT
041471,000112: 15,3663 77745 POSITA DLOAD
041472,000113: 15,3664 12004 KONMAT +2 # ZEROS
041473,000114: 15,3665 00027 STORE GTMP
041474,000115: 15,3666 40745 POSITB DLOAD DMP*
041475,000116: 15,3667 00031 TIMEP # T
041476,000117: 15,3670 12050 VAL67 +4,1 # 1/27 OR 1/32 OR 1/365
041477,000118: # Page 985
041478,000119: 15,3671 42661 SL DAD*
041479,000120: 15,3672 20211 8D
041480,000121: 15,3673 12046 VAL67 +2,1 # AARG
041481,000122: 15,3674 40756 SIN DMP* # SIN(T/27+PHI) OR T/32 OR T/365
041482,000123: 15,3675 12044 VAL67,1 # (A0**2+A1**2)**1/2 SIN(X+PHIA)
041483,000124: 15,3676 62015 DAD INCR,1 # PLUS
041484,000125: 15,3677 00027 GTMP # (B0**2+B1**2)**1/2 SIN(X+PHIB)
041485,000126: 15,3700 77771 DEC -6 B-14
041486,000127: 15,3701 00027 STORE GTMP # OR (C0**2+C1**2)**1/2 SIN(X+PHIC)
041487,000128: 15,3702 77614 BOFSET
041488,000129: 15,3703 00054 FREEFLAG
041489,000130: 15,3704 33666 POSITB
041490,000131: 15,3705 40745 POSITD DLOAD DMP*
041491,000132: 15,3706 00031 TIMEP # T
041492,000133: 15,3707 65747 RATESP,2 # LOMR,LOSR,LONR
041493,000134: 15,3710 42661 SL DAD*
041494,000135: 15,3711 20206 5D
041495,000136: 15,3712 65741 RATESP +6,2 # LOM0,LOS0,LON0
041496,000137: 15,3713 77625 DSU
041497,000138: 15,3714 00027 GTMP
041498,000139: 15,3715 10021 STORE STMP,2 # LOM,LOS,LON
041499,000140: 15,3716 63135 SLOAD INCR,2
041500,000141: 15,3717 00050 X2
041501,000142: 15,3720 77775 DEC -2 B-14
041502,000143: 15,3721 53015 DAD BZE
041503,000144: 15,3722 12026 RCB-13 # PLUS 2
041504,000145: 15,3723 33753 POSITE # 2ND
041505,000146: 15,3724 77644 BPL
041506,000147: 15,3725 33663 POSITA # 1ST
041507,000148: 15,3726 45345 POSITF DLOAD DSU # 3RD
041508,000149: 15,3727 00021 STMP # LOM
041509,000150: 15,3730 00025 STMP +4 # LON
041510,000151: 15,3731 65356 SIN PDDL # SIN(LOM-LON)
041511,000152: 15,3732 00021 STMP
041512,000153: 15,3733 65356 SIN PDDL # SIN LOM
041513,000154: 15,3734 00021 STMP
041514,000155: 15,3735 55546 COS VDEF # COS LOM
041515,000156: 15,3736 53521 MXV UNIT
041516,000157: 15,3737 12002 KONMAT # K1,K2,K3,K4
041517,000158: 15,3740 02723 STORE VMOON
041518,000159: 15,3741 65345 DLOAD PDDL
041519,000160: 15,3742 12004 KONMAT +2 # ZERO
041520,000161: 15,3743 00023 STMP +2
041521,000162: 15,3744 65356 SIN PDDL # SIN LOS
041522,000163: 15,3745 00023 STMP +2
041523,000164: 15,3746 55546 COS VDEF # COS LOS
041524,000165: 15,3747 53521 MXV UNIT
041525,000166: 15,3750 12002 KONMAT
041526,000167: 15,3751 02715 STORE VSUN
041527,000168: 15,3752 77616 RVQ
041528,000169: # Page 986
041529,000170: 15,3753 77745 POSITE DLOAD
041530,000171: 15,3754 12004 KONMAT +2 # ZEROS
041531,000172: 15,3755 00027 STORE GTMP
041532,000173: 15,3756 77650 GOTO
041533,000174: 15,3757 33705 POSITD
041534,000175: 05,2000 SETLOC EPHEM1
041535,000176: 05,2000 BANK
041536,000177:
041537,000178: 05,3505 COUNT* $$/EPHEM
041538,000179: 05,3505 STMP EQUALS 16D
041539,000180: 05,3505 GTMP EQUALS 22D
041540,000181: 05,3505 TIMEP EQUALS 24D
041541,000182:
041542,000183: # *** END OF LEMP50S .119 ***
End of include-file LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc. Parent file is MAIN.agc