Source Code
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These source-code files derive from a printout of Luminary 116 (the Apollo 12
Lunar Module guidance computer program), from the personal library of
original AGC developer Don Eyles, digitally photographed at archive.org,
financially sponsored by Ron Burkey, and transcribed to source code by a
team of volunteers. This colorized, syntax-highlighted form was created
by assembling that transcribed source code. Note that the full page images
are available on the
Virtual AGC project page at archive.org, while reduced-size images
are presented at the VirtualAGC project website. Report or fix any
transcription errors at
the Virtual AGC project code repository. Notations on the program listing read, in part: GAP: ASSEMBLE REVISION 116 OF AGC PROGRAM LUMINARY BY NASA 2021112-071 19:09 AUG. 11,1969Note that the date is the date of the printout, not the date of the program revision. |
042102,000002: ## Copyright: Public domain.
042103,000003: ## Filename: LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc
042104,000004: ## Purpose: A section of Luminary revision 116.
042105,000005: ## It is part of the source code for the Lunar Module's (LM)
042106,000006: ## Apollo Guidance Computer (AGC) for Apollo 12.
042107,000007: ## This file is intended to be a faithful transcription, except
042108,000008: ## that the code format has been changed to conform to the
042109,000009: ## requirements of the yaYUL assembler rather than the
042110,000010: ## original YUL assembler.
042111,000011: ## Reference: pp. 976-979
042112,000012: ## Assembler: yaYUL
042113,000013: ## Contact: Ron Burkey <info@sandroid.org>.
042114,000014: ## Website: www.ibiblio.org/apollo/index.html
042115,000015: ## Mod history: 2017-01-22 MAS Created from Luminary 99.
042116,000016: ## 2017-01-31 RRB Updated for Luminary 116.
042117,000017: ## 2017-03-13 RSB Proofed comment text via 3-way diff vs
042118,000018: ## Luminary 99 and 131.
042119,000019: ## 2017-08-26 MAS Fixed comment-text errors found while transcribing Zerlina 56.
042120,000020:
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Page 984 |
042122,000022: # NAME - LSPOS - LOCATE SUN AND MOON DATE - 25 OCT 67
042123,000023: # MOD NO. 1
042124,000024: # MOD BY NEVILLE ASSEMBLY SUNDANCE
042125,000025:
042126,000026: # FUNCTIONAL DESCRIPTION
042127,000027:
042128,000028: # COMPUTES UNIT POSITION VECTOR OF THE SUN AND MOON IN THE BASIC REFERENCE SYSTEM. THE SUN VECTOR S IS
042129,000029: # LOCATED VIA TWO ANGLES. THE FIRST ANGLE(OBLIQUITY) IS THE ANGLE BETWEEN THE EARTH EQUATOR AND THE ECLIPTIC. THE
042130,000030: # SECOND ANGLE IS THE LONGITUDE OF THE SUN MEASURED IN THE ECLIPTIC.
042131,000031: # THE POSITION VECTOR OF THE SUN IS
042132,000032: # -
042133,000033: # S = (COS(LOS), COS(OBL)*SIN(LOS), SIN(OBL)*SIN(LOS)), WHERE
042134,000034:
042135,000035: # LOS = LOS +LOS *T-(C *SIN(2PI*T)/365.24 +C *COS(2PI*T)/365.24)
042136,000036: # 0 R 0 1
042137,000037: # LOS (RAD) IS THE LONGITUDE OF THE SUN FOR MIDNIGHT JUNE 30TH OF THE PARTICULAR YEAR.
042138,000038: # 0
042139,000039: # LOS (RAD/DAY) IS THE MEAN RATE FOR THE PARTICULAR YEAR.
042140,000040: # R
042141,000041: # LOS AND LOS ARE STORED AS LOSC AND LOSR IN RATESP.
042142,000042: # 0 R
042143,000043: # COS(OBL) AND SIN(OBL) ARE STORED IN THE MATRIX KONMAT.
042144,000044: # T, TIME MEASURED IN DAYS (24 HOURS), IS STORED IN TIMEP.
042145,000045: # C AND C ARE FUDGE FACTORS TO MINIMIZE THE DEVIATION. THEY ARE STORED AS ONE CONSTANT (CMOD), SINCE
042146,000046: # 0 1 2 2 1/2
042147,000047: # C *SIN(X)+C *COS(X) CAN BE WRITTEN AS (C +C ) *SIN(X+PHI), WHERE PHI=ARCTAN(C /C ).
042148,000048: # 0 1 0 1 1 0
042149,000049:
042150,000050: # THE MOON IS LOCATED VIA FOUR ANGLES. THE FIRST IS THE OBLIQUITY. THE SECOND IS THE MEAN LONGITUDE OF THE MOON,
042151,000051: # MEASURED IN THE ECLIPTIC FROM THE MEAN EQUINOX TO THE MEAN ASCENDING NODE OF THE LUNAR ORBIT, AND THEN ALONG THE
042152,000052: # ORBIT. THE THIRD ANGLE IS THE ANGLE BETWEEN THE ECLIPTIC AND THE LUNAR ORBIT. THE FOURTH ANGLE IS THE LONGITUDE
042153,000053: # OF THE NODE OF THE MOON, MEASURED IN THE LUNAR ORBIT. LET THESE ANGLES BE OBL,LOM,IM, AND LON RESPECTIVELY.
042154,000054:
042155,000055: # THE SIMPLIFIED POSITION VECTOR OF THE MOON IS
042156,000056: # -
042157,000057: # 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))
042158,000058:
042159,000059: # WHERE
042160,000060: # 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
042161,000061: # 0 R 0 1 0 1
042162,000062: # LON=LON +LON
042163,000063: # 0 R
042164,000064: # A , A , B AND B ARE STORED AS AMOD AND BMOD (SEE DESCRIPTION OF CMOD, ABOVE). COS(OBL), SIN(OBL)*SIN(IM),
042165,000065: # 0 1 0 1
042166,000066: # SIN(OBL), AND COS(OBL)*SIN(IM) ARE STORED IN KONMAT AS K1, K2, K3 AND K4, RESPECTIVELY. LOM , LOM , LON , LON
042167,000067: # ARE STORED AS LOMO, LOMR, LONO, AND LONR IN RATESP. 0 R 0 R
042168,000068: # THE THREE PHIS ARE STORED AS AARG, BARG, AND CARG(SUN). ALL CONSTANTS ARE UPDATED BY YEAR.
042169,000069:
042170,000070: # CALLING SEQUENCE
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Page 977 |
042172,000072: # CALL LSPOS. RETURN IS VIA CPRET.
042173,000073:
042174,000074: # ALARMS OR ABORTS
042175,000075: # NONE
042176,000076:
042177,000077: # ERASABLE INITIALIZATION REQUIRED
042178,000078: # TEPHEM - TIME FROM MIDNIGHT 1 JULY PRECEDING THE LAUNCH TO THE TIME OF THE LAUNCH (WHEN THE AGC CLOCK WENT
042179,000079: # TO ZERO). TEPHEM IS TP WITH UNITS OF CENTI-SECONDS.
042180,000080: # TIME2 AND TIME1 ARE IN MPAC AND MPAC +1 WHEN PROGRAM IS CALLED.
042181,000081:
042182,000082: # OUTPUT
042183,000083: # UNIT POSITIONAL VECTOR OF SUN IN VSUN. (SCALED B-1)
042184,000084: # UNIT POSITIONAL VECTOR OF MOON IN VMOON. (SCALED B-1)
042185,000085:
042186,000086: # SUBROUTINES USED
042187,000087: # NONE
042188,000088:
042189,000089: # DEBRIS
042190,000090: # CURRENT CORE SET, WORK AREA AND FREEFLAG
042191,000091:
042192,000092: 04,3011 BANK 04
042193,000093: 15,2000 SETLOC EPHEM
042194,000094: 15,2000 BANK
042195,000095:
042196,000096: 15,3647 E5,1714 EBANK= VSUN
042197,000097: 15,3647 COUNT* $$/EPHEM
042198,000098: 15,3647 15,3647 LUNPOS EQUALS LSPOS
042199,000099:
042200,000100: 15,3647 54201 LSPOS SETPD SR
042201,000101: 15,3650 00001 0
042202,000102: 15,3651 20617 14D # TP
042203,000103: 15,3652 56371 TAD DDV
042204,000104: 15,3653 01707 TEPHEM # TIME OF LAUNCH
042205,000105: 15,3654 12024 CSTODAY # 24 HOURS-8640000 CENTI-SECS/DAY B-33
042206,000106: 15,3655 00031 STORE TIMEP # T IN DAYS
042207,000107: 15,3656 77170 AXT,1 AXT,2
042208,000108: 15,3657 00000 0
042209,000109: 15,3660 00000 0
042210,000110: 15,3661 77614 CLEAR
042211,000111: 15,3662 00274 FREEFLAG # SWITCH BIT
042212,000112: 15,3663 77745 POSITA DLOAD
042213,000113: 15,3664 12004 KONMAT +2 # ZEROS
042214,000114: 15,3665 00027 STORE GTMP
042215,000115: 15,3666 40745 POSITB DLOAD DMP*
042216,000116: 15,3667 00031 TIMEP # T
042217,000117: 15,3670 12050 VAL67 +4,1 # 1/27 OR 1/32 OR 1/365
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Page 978 |
042219,000119: 15,3671 42661 SL DAD*
042220,000120: 15,3672 20211 8D
042221,000121: 15,3673 12046 VAL67 +2,1 # AARG
042222,000122: 15,3674 40756 SIN DMP* # SIN(T/27+PHI) OR T/32 OR T/365
042223,000123: 15,3675 12044 VAL67,1 # (A0**2+A1**2)**1/2 SIN(X+PHIA)
042224,000124: 15,3676 62015 DAD INCR,1 # PLUS
042225,000125: 15,3677 00027 GTMP # (B0**2+B1**2)**1/2 SIN(X+PHIB)
042226,000126: 15,3700 77771 DEC -6 B-14
042227,000127: 15,3701 00027 STORE GTMP # OR (C0**2+C1**2)**1/2 SIN(X+PHIC)
042228,000128: 15,3702 77614 BOFSET
042229,000129: 15,3703 00054 FREEFLAG
042230,000130: 15,3704 33666 POSITB
042231,000131: 15,3705 40745 POSITD DLOAD DMP*
042232,000132: 15,3706 00031 TIMEP # T
042233,000133: 15,3707 65747 RATESP,2 # LOMR,LOSR,LONR
042234,000134: 15,3710 42661 SL DAD*
042235,000135: 15,3711 20206 5D
042236,000136: 15,3712 65741 RATESP +6,2 # LOMO,LOSO,LONO
042237,000137: 15,3713 77625 DSU
042238,000138: 15,3714 00027 GTMP
042239,000139: 15,3715 10021 STORE STMP,2 # LOM,LOS,LON
042240,000140: 15,3716 63135 SLOAD INCR,2
042241,000141: 15,3717 00050 X2
042242,000142: 15,3720 77775 DEC -2 B-14
042243,000143: 15,3721 53015 DAD BZE
042244,000144: 15,3722 12026 RCB-13 # PLUS 2
042245,000145: 15,3723 33753 POSITE # 2ND
042246,000146: 15,3724 77644 BPL
042247,000147: 15,3725 33663 POSITA # 1ST
042248,000148: 15,3726 45345 POSITF DLOAD DSU # 3RD
042249,000149: 15,3727 00021 STMP # LOM
042250,000150: 15,3730 00025 STMP +4 # LON
042251,000151: 15,3731 65356 SIN PDDL # SIN(LOM-LON)
042252,000152: 15,3732 00021 STMP
042253,000153: 15,3733 65356 SIN PDDL # SIN LOM
042254,000154: 15,3734 00021 STMP
042255,000155: 15,3735 55546 COS VDEF # COS LOM
042256,000156: 15,3736 53521 MXV UNIT
042257,000157: 15,3737 12002 KONMAT # K1,K2,K3,K4,
042258,000158: 15,3740 02723 STORE VMOON
042259,000159: 15,3741 65345 DLOAD PDDL
042260,000160: 15,3742 12004 KONMAT +2 # ZERO
042261,000161: 15,3743 00023 STMP +2
042262,000162: 15,3744 65356 SIN PDDL # SIN LOS
042263,000163: 15,3745 00023 STMP +2
042264,000164: 15,3746 55546 COS VDEF # COS LOS
042265,000165: 15,3747 53521 MXV UNIT
042266,000166: 15,3750 12002 KONMAT
042267,000167: 15,3751 02715 STORE VSUN
042268,000168: 15,3752 77616 RVQ
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Page 979 |
042270,000170: 15,3753 77745 POSITE DLOAD
042271,000171: 15,3754 12004 KONMAT +2 # ZEROS
042272,000172: 15,3755 00027 STORE GTMP
042273,000173: 15,3756 77650 GOTO
042274,000174: 15,3757 33705 POSITD
042275,000175: 05,2000 SETLOC EPHEM1
042276,000176: 05,2000 BANK
042277,000177:
042278,000178: 05,3472 COUNT* $$/EPHEM
042279,000179:
042280,000180: 05,3472 STMP EQUALS 16D
042281,000181:
042282,000182: 05,3472 GTMP EQUALS 22D
042283,000183:
042284,000184: 05,3472 TIMEP EQUALS 24D
042285,000185:
End of include-file LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc. Parent file is MAIN.agc