Source Code

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. 11,1969
Note 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: 

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

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

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                                            

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