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!

042091,000002:                                                                                                  ## Copyright:   Public domain.
042092,000003:                                                                                                  ## Filename:    LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc
042093,000004:                                                                                                  ## Purpose:     Part of the source code for Luminary 1A build 099.
042094,000005:                                                                                                  ##              It is part of the source code for the Lunar Module's (LM)
042095,000006:                                                                                                  ##              Apollo Guidance Computer (AGC), for Apollo 11.
042096,000007:                                                                                                  ## Assembler:   yaYUL
042097,000008:                                                                                                  ## Contact:     Hartmuth Gutsche <hgutsche@xplornet.com>.
042098,000009:                                                                                                  ## Website:     www.ibiblio.org/apollo.
042099,000010:                                                                                                  ## Pages:       984-987
042100,000011:                                                                                                  ## Mod history: 2009-05-24 HG   Transcribed from page images.
042101,000012:                                                                                                  ##              2016-12-17 RSB  Proofed text comments with octopus/ProoferComments
042102,000013:                                                                                                  ##                              and corrected the errors found.
042103,000014:                                                                                                  ##              2017-03-03 RSB  Snapshot of Luminary 99 Rev 1. 
042104,000015:                                                                                                  ##              2017-03-13 RSB  Comment-text fixes noted in proofing Luminary 116.
042105,000016: 

Page 984

042107,000018:                                                                                                  #  NAME - LSPOS - LOCATE SUN AND MOON                    DATE - 25 OCT 67
042108,000019:                                                                                                  #  MOD NO. 1
042109,000020:                                                                                                  #  MOD BY NEVILLE                                        ASSEMBLY SUNDANCE
042110,000021: 
042111,000022:                                                                                                  #  FUNCTIONAL DESCRIPTION
042112,000023: 
042113,000024:                                                                                                  #         COMPUTES UNIT POSITION VECTOR OF THE SUN AND MOON IN THE BASIC REFERENCE SYSTEM. THE SUN VECTOR S IS
042114,000025:                                                                                                  #  LOCATED VIA TWO ANGLES. THE FIRST ANGLE(OBLIQUITY) IS THE ANGLE BETWEEN THE EARTH EQUATOR AND THE ECLIPTIC. THE
042115,000026:                                                                                                  #  SECOND ANGLE IS THE LONGITUDE OF THE SUN MEASURED IN THE ECLIPTIC.
042116,000027:                                                                                                  #  THE POSITION VECTOR OF THE SUN IS
042117,000028:                                                                                                  #        -
042118,000029:                                                                                                  #        S = (COS(LOS), COS(OBL)*SIN(LOS), SIN(OBL)*SIN(LOS)), WHERE
042119,000030: 
042120,000031:                                                                                                  #        LOS = LOS +LOS *T-(C *SIN(2PI*T)/365.24 +C *COS(2PI*T)/365.24)
042121,000032:                                                                                                  #                 0    R     0                     1
042122,000033:                                                                                                  #        LOS  (RAD) IS THE LONGITUDE OF THE SUN FOR MIDNIGHT JUNE 30TH OF THE PARTICULAR YEAR.
042123,000034:                                                                                                  #           0
042124,000035:                                                                                                  #        LOS  (RAD/DAY) IS THE MEAN RATE FOR THE PARTICULAR YEAR.
042125,000036:                                                                                                  #           R
042126,000037: 
042127,000038:                                                                                                  #  LOS  AND LOS  ARE STORED AS LOSC AND LOSR IN RATESP.
042128,000039:                                                                                                  #     0        R
042129,000040:                                                                                                  #  COS(OBL) AND SIN(OBL) ARE STORED IN THE MATRIX KONMAT.
042130,000041: 
042131,000042:                                                                                                  #  T, TIME MEASURED IN DAYS (24 HOURS), IS STORED IN TIMEP.
042132,000043: 
042133,000044:                                                                                                  #  C  AND C  ARE FUDGE FACTORS TO MINIMIZE THE DEVIATION.  THEY ARE STORED AS ONE CONSTANT (CMOD), SINCE
042134,000045:                                                                                                  #   0      1                               2  2 1/2
042135,000046:                                                                                                  #  C *SIN(X)+C *COS(X) CAN BE WRITTEN AS (C +C )   *SIN(X+PHI), WHERE PHI=ARCTAN(C /C ).
042136,000047:                                                                                                  #   0         1                            0  1                                   1  0
042137,000048: 
042138,000049:                                                                                                  #  THE MOON IS LOCATED VIA FOUR ANGLES, THE FIRST IS THE OBLIQUITY. THE SECOND IS THE MEAN LONGITUDE OF THE MOON,
042139,000050:                                                                                                  #  MEASURED IN THE ECLIPTIC FROM THE MEAN EQUINOX TO THE MEAN ASCENDING NODE OF THE LUNAR ORBIT, AND THEN ALONG THE
042140,000051:                                                                                                  #  ORBIT.  THE THIRD ANGLE IS THE ANGLE BETWEEN THE ECLIPTIC AND THE LUNAR ORBIT.  THE FOURTH ANGLE IS THE LONGITUDE
042141,000052:                                                                                                  #  OF THE NODE OF THE MOON, MEASURED IN THE LUNAR ORBIT.  LET THESE ANGLES BE OBL,LOM,IM, AND LON RESPECTIVELY.
042142,000053: 
042143,000054:                                                                                                  #  THE SIMPLIFIED POSITION VECTOR OF THE MOON IS
042144,000055:                                                                                                  #        -
042145,000056:                                                                                                  #        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))
042146,000057: 
042147,000058:                                                                                                  #  WHERE
042148,000059:                                                                                                  #        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
042149,000060:                                                                                                  #               0    R     0                    1                     0               1
042150,000061:                                                                                                  #        LON=LON +LON
042151,000062:                                                                                                  #               0    R
042152,000063:                                                                                                  #  A , A , B  AND B  ARE STORED AS AMOD AND BMOD (SEE DESCRIPTION OF CMOD, ABOVE).  COS(OBL), SIN(OBL)*SIN(IM),
042153,000064:                                                                                                  #   0   1   0      1
042154,000065:                                                                                                  #  SIN(OBL), AND COS(OBL)*SIN(IM) ARE STORED IN KONMAT AS K1, K2, K3 AND K4, RESPECTIVELY.  LOM , LOM , LON , LON                                   
042155,000066:                                                                                                  #  ARE STORED AS LOM0, LOMR, LON0, AND LONR IN RATESP.                                         0     R     0     R
042156,000067:                                                                                                  #  THE THREE PHIS ARE STORED AS AARG, BARG, AND CARG(SUN).  ALL CONSTANTS ARE UPDATED BY YEAR.
042157,000068: 
042158,000069:                                                                                                  #  CALLING SEQUENCE

Page 985

042160,000071:                                                                                                  #        CALL LSPOS.  RETURN IS VIA CPRET.
042161,000072: 
042162,000073:                                                                                                  #  ALARMS OR ABORTS
042163,000074:                                                                                                  #        NONE
042164,000075: 
042165,000076:                                                                                                  #  ERASABLE INITIALIZATION REQUIRED
042166,000077:                                                                                                  #        TEPHEM - TIME FROM MIDNIGHT 1 JULY PRECEDING THE LAUNCH TO THE TIME OF THE LAUNCH (WHEN THE AGC CLOCK WENT
042167,000078:                                                                                                  #        TO ZERO).  TEPHEM IS TP WITH UNITS OF CENTI-SECONDS.
042168,000079: 
042169,000080:                                                                                                  #        TIME2 AND TIME1 ARE IN MPAC AND MPAC +1 WHEN PROGRAM IS CALLED.
042170,000081: 
042171,000082:                                                                                                  #  OUTPUT
042172,000083:                                                                                                  #        UNIT POSITIONAL VECTOR OF SUN IN VSUN.  (SCALED B-1)
042173,000084:                                                                                                  #        UNIT POSITIONAL VECTOR OF MOON IN VMOON.  (SCALED B-1)
042174,000085: 
042175,000086:                                                                                                  #  SUBROUTINES USED
042176,000087:                                                                                                  #        NONE
042177,000088: 
042178,000089:                                                                                                  #  DEBRIS
042179,000090:                                                                                                  #        CURRENT CORE SET, WORK AREA AND FREEFLAG
042180,000091: 
042181,000092: 04,3027                                           BANK     04                                    
042182,000093: 15,2000                                           SETLOC   EPHEM                                 
042183,000094: 15,2000                                           BANK                                           
042184,000095: 
042185,000096: 15,3664  E5,1714                                  EBANK=   VSUN                                  
042186,000097: 15,3664                                           COUNT*   $$/EPHEM                              
042187,000098: 15,3664  15,3664               LUNPOS             EQUALS   LSPOS                                 
042188,000099: 
042189,000100: 15,3664           54201        LSPOS              SETPD    SR                                    
042190,000101: 15,3665           00001                                    0                                     
042191,000102: 15,3666           20617                                    14D                                   #  TP
042192,000103: 15,3667           56371                           TAD      DDV                                   

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

042194,000105: 15,3670           01707                                    TEPHEM                                #  TIME OF LAUNCH
042195,000106: 15,3671           12024                                    CSTODAY                               #  24 HOURS-8640000 CENTI-SECS/DAY B-33

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

042197,000108: 15,3672           00031                           STORE    TIMEP                                 #  T IN DAYS

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

042199,000110: 15,3673           77170                           AXT,1    AXT,2                                 
042200,000111: 15,3674           00000                                    0                                     
042201,000112: 15,3675           00000                                    0                                     
042202,000113: 15,3676           77614                           CLEAR                                          
042203,000114: 15,3677           00274                                    FREEFLAG                              #  SWITCH BIT
042204,000115: 15,3700           77745        POSITA             DLOAD                                          
042205,000116: 15,3701           12004                                    KONMAT     +2                         #  ZEROS
042206,000117: 15,3702           00027                           STORE    GTMP                                  
042207,000118: 15,3703           40745        POSITB             DLOAD    DMP*                                  
042208,000119: 15,3704           00031                                    TIMEP                                 #  T
042209,000120: 15,3705           12050                                    VAL67      +4,1                       #  1/27 OR 1/32 OR 1/365

Page 986

042211,000122: 15,3706           42661                           SL       DAD*                                  
042212,000123: 15,3707           20211                                    8D                                    
042213,000124: 15,3710           12046                                    VAL67      +2,1                       #  AARG
042214,000125: 15,3711           40756                           SIN      DMP*                                  #  SIN(T/27+PHI) OR T/32 OR T/365
042215,000126: 15,3712           12044                                    VAL67,1                               #  (A0**2+A1**2)**1/2 SIN(X+PHIA)
042216,000127: 15,3713           62015                           DAD      INCR,1                                #  PLUS
042217,000128: 15,3714           00027                                    GTMP                                  #  (B0**2+B1**2)**1/2 SIN(X+PHIB)
042218,000129: 15,3715           77771                           DEC      -6         B-14                       
042219,000130: 15,3716           00027                           STORE    GTMP                                  #  OR (C0**2+C1**2)**1/2 SIN(X+PHIC)
042220,000131: 15,3717           77614                           BOFSET                                         
042221,000132: 15,3720           00054                                    FREEFLAG                              
042222,000133: 15,3721           33703                                    POSITB                                
042223,000134: 15,3722           40745        POSITD             DLOAD    DMP*                                  
042224,000135: 15,3723           00031                                    TIMEP                                 #  T
042225,000136: 15,3724           65747                                    RATESP,2                              #  LOMR,LOSR,LONR
042226,000137: 15,3725           42661                           SL       DAD*                                  
042227,000138: 15,3726           20206                                    5D                                    
042228,000139: 15,3727           65741                                    RATESP     +6,2                       #  LOMO,LOSO,LONO
042229,000140: 15,3730           77625                           DSU                                            
042230,000141: 15,3731           00027                                    GTMP                                  
042231,000142: 15,3732           10021                           STORE    STMP,2                                #  LOM,LOS,LON
042232,000143: 15,3733           63135                           SLOAD    INCR,2                                
042233,000144: 15,3734           00050                                    X2                                    
042234,000145: 15,3735           77775                           DEC      -2         B-14                       
042235,000146: 15,3736           53015                           DAD      BZE                                   
042236,000147: 15,3737           12026                                    RCB-13                                #  PLUS 2
042237,000148: 15,3740           33770                                    POSITE                                #  2ND
042238,000149: 15,3741           77644                           BPL                                            
042239,000150: 15,3742           33700                                    POSITA                                #  1ST
042240,000151: 15,3743           45345        POSITF             DLOAD    DSU                                   #  3RD
042241,000152: 15,3744           00021                                    STMP                                  #  LOM
042242,000153: 15,3745           00025                                    STMP       +4                         #  LON
042243,000154: 15,3746           65356                           SIN      PDDL                                  #  SIN(LOM-LON)
042244,000155: 15,3747           00021                                    STMP                                  
042245,000156: 15,3750           65356                           SIN      PDDL                                  #  SIN LOM
042246,000157: 15,3751           00021                                    STMP                                  
042247,000158: 15,3752           55546                           COS      VDEF                                  #  COS LOM
042248,000159: 15,3753           53521                           MXV      UNIT                                  
042249,000160: 15,3754           12002                                    KONMAT                                #  K1,K2,K3,K4,
042250,000161: 15,3755           02723                           STORE    VMOON                                 
042251,000162: 15,3756           65345                           DLOAD    PDDL                                  
042252,000163: 15,3757           12004                                    KONMAT     +2                         #  ZERO
042253,000164: 15,3760           00023                                    STMP       +2                         
042254,000165: 15,3761           65356                           SIN      PDDL                                  #  SIN LOS
042255,000166: 15,3762           00023                                    STMP       +2                         
042256,000167: 15,3763           55546                           COS      VDEF                                  #  COS LOS
042257,000168: 15,3764           53521                           MXV      UNIT                                  
042258,000169: 15,3765           12002                                    KONMAT                                
042259,000170: 15,3766           02715                           STORE    VSUN                                  
042260,000171: 15,3767           77616                           RVQ                                            

Page 987

042262,000173: 15,3770           77745        POSITE             DLOAD                                          
042263,000174: 15,3771           12004                                    KONMAT     +2                         #  ZEROS
042264,000175: 15,3772           00027                           STORE    GTMP                                  
042265,000176: 15,3773           77650                           GOTO                                           
042266,000177: 15,3774           33722                                    POSITD                                
042267,000178: 15,3775           77616        LUNVEL             RVQ                                            #         TO FOOL INTEGRATION
042268,000179: 05,2000                                           SETLOC   EPHEM1                                
042269,000180: 05,2000                                           BANK                                           
042270,000181: 
042271,000182: 05,3506                                           COUNT*   $$/EPHEM                              
042272,000183: 05,3506                        STMP               EQUALS   16D                                   
042273,000184: 05,3506                        GTMP               EQUALS   22D                                   
042274,000185: 05,3506                        TIMEP              EQUALS   24D                                   
042275,000186: 

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