Source Code

This is an attempt to recreate Luminary 99 Rev 2, otherwise known as LUM99R2, from Luminary 99 Rev 1 and ephemeris data from Luminary 116. The differences are confined to the last 10-12 lines of the CONTROLLED CONSTANTS. Luminary 99 Rev 1 source-code was transcribed from a printout in the MIT Museum, while Luminary 116 source code was transcribed from a printout belonging to Don Eyles. AGC developer James Kernan, the "rope mother" for the Apollo 11 Lunar Module's AGC, explains as follows: "At the last minute, Dan Lickly, our chief engineer, appeared with ephemerides updates and it took two tries to get it right. The result was that we created Lum99 Revision 1 and Lum99 Revision 2." It is suspected that the former is what's in the MIT Museum, and the latter is what we are trying to recreate here. As for which revision actually flew in Apollo 11, all of the other available surviving evidence points to Rev 1 rather than to Rev 2, so we're just not sure!

042099,000002:                                                                                                  ## Copyright:   Public domain.
042100,000003:                                                                                                  ## Filename:    LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc
042101,000004:                                                                                                  ## Purpose:     Part of the source code for Luminary 1A build 099.
042102,000005:                                                                                                  ##              It is part of the source code for the Lunar Module's (LM)
042103,000006:                                                                                                  ##              Apollo Guidance Computer (AGC), for Apollo 11.
042104,000007:                                                                                                  ## Assembler:   yaYUL
042105,000008:                                                                                                  ## Contact:     Hartmuth Gutsche <hgutsche@xplornet.com>.
042106,000009:                                                                                                  ## Website:     www.ibiblio.org/apollo.
042107,000010:                                                                                                  ## Pages:       984-987
042108,000011:                                                                                                  ## Mod history: 2009-05-24 HG   Transcribed from page images.
042109,000012:                                                                                                  ##              2016-12-17 RSB  Proofed text comments with octopus/ProoferComments
042110,000013:                                                                                                  ##                              and corrected the errors found.
042111,000014:                                                                                                  ##              2017-03-03 RSB  Snapshot of Luminary 99 Rev 1. 
042112,000015:                                                                                                  ##              2017-03-13 RSB  Comment-text fixes noted in proofing Luminary 116.
042113,000016:                                                                                                  ##              2017-08-26 MAS  Fixed comment-text errors found while transcribing Zerlina 56.
042114,000017: 

Page 984

042116,000019:                                                                                                  #  NAME - LSPOS - LOCATE SUN AND MOON                    DATE - 25 OCT 67
042117,000020:                                                                                                  #  MOD NO. 1
042118,000021:                                                                                                  #  MOD BY NEVILLE                                        ASSEMBLY SUNDANCE
042119,000022: 
042120,000023:                                                                                                  #  FUNCTIONAL DESCRIPTION
042121,000024: 
042122,000025:                                                                                                  #         COMPUTES UNIT POSITION VECTOR OF THE SUN AND MOON IN THE BASIC REFERENCE SYSTEM. THE SUN VECTOR S IS
042123,000026:                                                                                                  #  LOCATED VIA TWO ANGLES. THE FIRST ANGLE(OBLIQUITY) IS THE ANGLE BETWEEN THE EARTH EQUATOR AND THE ECLIPTIC. THE
042124,000027:                                                                                                  #  SECOND ANGLE IS THE LONGITUDE OF THE SUN MEASURED IN THE ECLIPTIC.
042125,000028:                                                                                                  #  THE POSITION VECTOR OF THE SUN IS
042126,000029:                                                                                                  #        -
042127,000030:                                                                                                  #        S = (COS(LOS), COS(OBL)*SIN(LOS), SIN(OBL)*SIN(LOS)), WHERE
042128,000031: 
042129,000032:                                                                                                  #        LOS = LOS +LOS *T-(C *SIN(2PI*T)/365.24 +C *COS(2PI*T)/365.24)
042130,000033:                                                                                                  #                 0    R     0                     1
042131,000034:                                                                                                  #        LOS  (RAD) IS THE LONGITUDE OF THE SUN FOR MIDNIGHT JUNE 30TH OF THE PARTICULAR YEAR.
042132,000035:                                                                                                  #           0
042133,000036:                                                                                                  #        LOS  (RAD/DAY) IS THE MEAN RATE FOR THE PARTICULAR YEAR.
042134,000037:                                                                                                  #           R
042135,000038: 
042136,000039:                                                                                                  #  LOS  AND LOS  ARE STORED AS LOSC AND LOSR IN RATESP.
042137,000040:                                                                                                  #     0        R
042138,000041:                                                                                                  #  COS(OBL) AND SIN(OBL) ARE STORED IN THE MATRIX KONMAT.
042139,000042: 
042140,000043:                                                                                                  #  T, TIME MEASURED IN DAYS (24 HOURS), IS STORED IN TIMEP.
042141,000044: 
042142,000045:                                                                                                  #  C  AND C  ARE FUDGE FACTORS TO MINIMIZE THE DEVIATION.  THEY ARE STORED AS ONE CONSTANT (CMOD), SINCE
042143,000046:                                                                                                  #   0      1                               2  2 1/2
042144,000047:                                                                                                  #  C *SIN(X)+C *COS(X) CAN BE WRITTEN AS (C +C )   *SIN(X+PHI), WHERE PHI=ARCTAN(C /C ).
042145,000048:                                                                                                  #   0         1                            0  1                                   1  0
042146,000049: 
042147,000050:                                                                                                  #  THE MOON IS LOCATED VIA FOUR ANGLES. THE FIRST IS THE OBLIQUITY. THE SECOND IS THE MEAN LONGITUDE OF THE MOON,
042148,000051:                                                                                                  #  MEASURED IN THE ECLIPTIC FROM THE MEAN EQUINOX TO THE MEAN ASCENDING NODE OF THE LUNAR ORBIT, AND THEN ALONG THE
042149,000052:                                                                                                  #  ORBIT.  THE THIRD ANGLE IS THE ANGLE BETWEEN THE ECLIPTIC AND THE LUNAR ORBIT.  THE FOURTH ANGLE IS THE LONGITUDE
042150,000053:                                                                                                  #  OF THE NODE OF THE MOON, MEASURED IN THE LUNAR ORBIT.  LET THESE ANGLES BE OBL,LOM,IM, AND LON RESPECTIVELY.
042151,000054: 
042152,000055:                                                                                                  #  THE SIMPLIFIED POSITION VECTOR OF THE MOON IS
042153,000056:                                                                                                  #        -
042154,000057:                                                                                                  #        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))
042155,000058: 
042156,000059:                                                                                                  #  WHERE
042157,000060:                                                                                                  #        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
042158,000061:                                                                                                  #               0    R     0                    1                     0               1
042159,000062:                                                                                                  #        LON=LON +LON
042160,000063:                                                                                                  #               0    R
042161,000064:                                                                                                  #  A , A , B  AND B  ARE STORED AS AMOD AND BMOD (SEE DESCRIPTION OF CMOD, ABOVE).  COS(OBL), SIN(OBL)*SIN(IM),
042162,000065:                                                                                                  #   0   1   0      1
042163,000066:                                                                                                  #  SIN(OBL), AND COS(OBL)*SIN(IM) ARE STORED IN KONMAT AS K1, K2, K3 AND K4, RESPECTIVELY.  LOM , LOM , LON , LON                                   
042164,000067:                                                                                                  #  ARE STORED AS LOMO, LOMR, LONO, AND LONR IN RATESP.                                         0     R     0     R
042165,000068:                                                                                                  #  THE THREE PHIS ARE STORED AS AARG, BARG, AND CARG(SUN).  ALL CONSTANTS ARE UPDATED BY YEAR.
042166,000069: 
042167,000070:                                                                                                  #  CALLING SEQUENCE

Page 985

042169,000072:                                                                                                  #        CALL LSPOS.  RETURN IS VIA CPRET.
042170,000073: 
042171,000074:                                                                                                  #  ALARMS OR ABORTS
042172,000075:                                                                                                  #        NONE
042173,000076: 
042174,000077:                                                                                                  #  ERASABLE INITIALIZATION REQUIRED
042175,000078:                                                                                                  #        TEPHEM - TIME FROM MIDNIGHT 1 JULY PRECEDING THE LAUNCH TO THE TIME OF THE LAUNCH (WHEN THE AGC CLOCK WENT
042176,000079:                                                                                                  #        TO ZERO).  TEPHEM IS TP WITH UNITS OF CENTI-SECONDS.
042177,000080: 
042178,000081:                                                                                                  #        TIME2 AND TIME1 ARE IN MPAC AND MPAC +1 WHEN PROGRAM IS CALLED.
042179,000082: 
042180,000083:                                                                                                  #  OUTPUT
042181,000084:                                                                                                  #        UNIT POSITIONAL VECTOR OF SUN IN VSUN.  (SCALED B-1)
042182,000085:                                                                                                  #        UNIT POSITIONAL VECTOR OF MOON IN VMOON.  (SCALED B-1)
042183,000086: 
042184,000087:                                                                                                  #  SUBROUTINES USED
042185,000088:                                                                                                  #        NONE
042186,000089: 
042187,000090:                                                                                                  #  DEBRIS
042188,000091:                                                                                                  #        CURRENT CORE SET, WORK AREA AND FREEFLAG
042189,000092: 
042190,000093: 04,3027                                           BANK     04                                    
042191,000094: 15,2000                                           SETLOC   EPHEM                                 
042192,000095: 15,2000                                           BANK                                           
042193,000096: 
042194,000097: 15,3664  E5,1714                                  EBANK=   VSUN                                  
042195,000098: 15,3664                                           COUNT*   $$/EPHEM                              
042196,000099: 15,3664  15,3664               LUNPOS             EQUALS   LSPOS                                 
042197,000100: 
042198,000101: 15,3664           54201        LSPOS              SETPD    SR                                    
042199,000102: 15,3665           00001                                    0                                     
042200,000103: 15,3666           20617                                    14D                                   #  TP
042201,000104: 15,3667           56371                           TAD      DDV                                   

The hand-written notation "in centisec B 42" appears to the right.

042203,000106: 15,3670           01707                                    TEPHEM                                #  TIME OF LAUNCH
042204,000107: 15,3671           12024                                    CSTODAY                               #  24 HOURS-8640000 CENTI-SECS/DAY B-33

The hand-written notation "@ B 9 = 512 days" appears to the right.

042206,000109: 15,3672           00031                           STORE    TIMEP                                 #  T IN DAYS

The hand-written notation "∴ granularity ≈ 0.164 sec" appears to the right.

042208,000111: 15,3673           77170                           AXT,1    AXT,2                                 
042209,000112: 15,3674           00000                                    0                                     
042210,000113: 15,3675           00000                                    0                                     
042211,000114: 15,3676           77614                           CLEAR                                          
042212,000115: 15,3677           00274                                    FREEFLAG                              #  SWITCH BIT
042213,000116: 15,3700           77745        POSITA             DLOAD                                          
042214,000117: 15,3701           12004                                    KONMAT     +2                         #  ZEROS
042215,000118: 15,3702           00027                           STORE    GTMP                                  
042216,000119: 15,3703           40745        POSITB             DLOAD    DMP*                                  
042217,000120: 15,3704           00031                                    TIMEP                                 #  T
042218,000121: 15,3705           12050                                    VAL67      +4,1                       #  1/27 OR 1/32 OR 1/365

Page 986

042220,000123: 15,3706           42661                           SL       DAD*                                  
042221,000124: 15,3707           20211                                    8D                                    
042222,000125: 15,3710           12046                                    VAL67      +2,1                       #  AARG
042223,000126: 15,3711           40756                           SIN      DMP*                                  #  SIN(T/27+PHI) OR T/32 OR T/365
042224,000127: 15,3712           12044                                    VAL67,1                               #  (A0**2+A1**2)**1/2 SIN(X+PHIA)
042225,000128: 15,3713           62015                           DAD      INCR,1                                #  PLUS
042226,000129: 15,3714           00027                                    GTMP                                  #  (B0**2+B1**2)**1/2 SIN(X+PHIB)
042227,000130: 15,3715           77771                           DEC      -6         B-14                       
042228,000131: 15,3716           00027                           STORE    GTMP                                  #  OR (C0**2+C1**2)**1/2 SIN(X+PHIC)
042229,000132: 15,3717           77614                           BOFSET                                         
042230,000133: 15,3720           00054                                    FREEFLAG                              
042231,000134: 15,3721           33703                                    POSITB                                
042232,000135: 15,3722           40745        POSITD             DLOAD    DMP*                                  
042233,000136: 15,3723           00031                                    TIMEP                                 #  T
042234,000137: 15,3724           65747                                    RATESP,2                              #  LOMR,LOSR,LONR
042235,000138: 15,3725           42661                           SL       DAD*                                  
042236,000139: 15,3726           20206                                    5D                                    
042237,000140: 15,3727           65741                                    RATESP     +6,2                       #  LOMO,LOSO,LONO
042238,000141: 15,3730           77625                           DSU                                            
042239,000142: 15,3731           00027                                    GTMP                                  
042240,000143: 15,3732           10021                           STORE    STMP,2                                #  LOM,LOS,LON
042241,000144: 15,3733           63135                           SLOAD    INCR,2                                
042242,000145: 15,3734           00050                                    X2                                    
042243,000146: 15,3735           77775                           DEC      -2         B-14                       
042244,000147: 15,3736           53015                           DAD      BZE                                   
042245,000148: 15,3737           12026                                    RCB-13                                #  PLUS 2
042246,000149: 15,3740           33770                                    POSITE                                #  2ND
042247,000150: 15,3741           77644                           BPL                                            
042248,000151: 15,3742           33700                                    POSITA                                #  1ST
042249,000152: 15,3743           45345        POSITF             DLOAD    DSU                                   #  3RD
042250,000153: 15,3744           00021                                    STMP                                  #  LOM
042251,000154: 15,3745           00025                                    STMP       +4                         #  LON
042252,000155: 15,3746           65356                           SIN      PDDL                                  #  SIN(LOM-LON)
042253,000156: 15,3747           00021                                    STMP                                  
042254,000157: 15,3750           65356                           SIN      PDDL                                  #  SIN LOM
042255,000158: 15,3751           00021                                    STMP                                  
042256,000159: 15,3752           55546                           COS      VDEF                                  #  COS LOM
042257,000160: 15,3753           53521                           MXV      UNIT                                  
042258,000161: 15,3754           12002                                    KONMAT                                #  K1,K2,K3,K4,
042259,000162: 15,3755           02723                           STORE    VMOON                                 
042260,000163: 15,3756           65345                           DLOAD    PDDL                                  
042261,000164: 15,3757           12004                                    KONMAT     +2                         #  ZERO
042262,000165: 15,3760           00023                                    STMP       +2                         
042263,000166: 15,3761           65356                           SIN      PDDL                                  #  SIN LOS
042264,000167: 15,3762           00023                                    STMP       +2                         
042265,000168: 15,3763           55546                           COS      VDEF                                  #  COS LOS
042266,000169: 15,3764           53521                           MXV      UNIT                                  
042267,000170: 15,3765           12002                                    KONMAT                                
042268,000171: 15,3766           02715                           STORE    VSUN                                  
042269,000172: 15,3767           77616                           RVQ                                            

Page 987

042271,000174: 15,3770           77745        POSITE             DLOAD                                          
042272,000175: 15,3771           12004                                    KONMAT     +2                         #  ZEROS
042273,000176: 15,3772           00027                           STORE    GTMP                                  
042274,000177: 15,3773           77650                           GOTO                                           
042275,000178: 15,3774           33722                                    POSITD                                
042276,000179: 15,3775           77616        LUNVEL             RVQ                                            #         TO FOOL INTEGRATION
042277,000180: 05,2000                                           SETLOC   EPHEM1                                
042278,000181: 05,2000                                           BANK                                           
042279,000182: 
042280,000183: 05,3506                                           COUNT*   $$/EPHEM                              
042281,000184: 05,3506                        STMP               EQUALS   16D                                   
042282,000185: 05,3506                        GTMP               EQUALS   22D                                   
042283,000186: 05,3506                        TIMEP              EQUALS   24D                                   
042284,000187: 

End of include-file LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc.  Parent file is MAIN.agc