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!

047419,000002:                                                                                                  ## Copyright:   Public domain.
047420,000003:                                                                                                  ## Filename:    LATITUDE_LONGITUDE_SUBROUTINES.agc
047421,000004:                                                                                                  ## Purpose:     Part of the source code for Luminary 1A build 099.
047422,000005:                                                                                                  ##              It is part of the source code for the Lunar Module's (LM)
047423,000006:                                                                                                  ##              Apollo Guidance Computer (AGC), for Apollo 11.
047424,000007:                                                                                                  ##
047425,000008:                                                                                                  ## Assembler:   yaYUL
047426,000009:                                                                                                  ## Contact:     Jim Lawton <jim DOT lawton AT gmail DOT com>
047427,000010:                                                                                                  ## Website:     www.ibiblio.org/apollo.
047428,000011:                                                                                                  ## Pages:       1133-1139
047429,000012:                                                                                                  ## Mod history: 2009-05-28 JL   Updated from page images.
047430,000013:                                                                                                  ##              2011-01-06 JL   Fixed interpretive indentation.
047431,000014:                                                                                                  ##              2016-12-17 RSB  Proofed text comments with octopus/ProoferComments
047432,000015:                                                                                                  ##                              and corrected the errors found.
047433,000016:                                                                                                  ##              2017-03-03 RSB  Snapshot of Luminary 99 Rev 1. 
047434,000017:                                                                                                  ##              2017-03-15 RSB  Comment-text fixes identified in 5-way
047435,000018:                                                                                                  ##                              side-by-side diff of Luminary 69/99/116/131/210.
047436,000019: 

Page 1133

047438,000021:                                                                                                  #  SUBROUTINE TO CONVERT RAD VECTOR AT GIVEN TIME TO LAT,LONG AND ALT
047439,000022: 
047440,000023:                                                                                                  #  CALLING SEQUENCE
047441,000024:                                                                                                  #        L-1     CALL
047442,000025:                                                                                                  #        L               LAT-LONG
047443,000026: 
047444,000027:                                                                                                  #  SUBROUTINES USED
047445,000028:                                                                                                  #        R-TO-RP, ARCTAN, SETGAMMA, SETRE
047446,000029: 
047447,000030:                                                                                                  #  ERASABLE INIT. REQ.
047448,000031:                                                                                                  #        AXO, -AYO, AZO, TEPHEM (SET AT LAUNCH TIME)
047449,000032:                                                                                                  #        ALPHAV = POSITION VECTOR METERS B-29
047450,000033:                                                                                                  #        MPAC -- TIME (CSECS B-28)
047451,000034:                                                                                                  #        ERADFLAG =1, TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047452,000035:                                                                                                  #        LUNAFLAG=0 FOR EARTH, 1 FOR MOON
047453,000036: 
047454,000037:                                                                                                  #  OUTPUT
047455,000038:                                                                                                  #        LATITUDE IN LAT         (REVS. B-0)
047456,000039:                                                                                                  #        LONGITUDE IN LONG       (REVS. B-0)
047457,000040:                                                                                                  #        ALTITUDE IN ALT         METERS B-29
047458,000041: 
047459,000042: 30,3775                                           BANK     30                                    
047460,000043: 13,2000                                           SETLOC   LATLONG                               
047461,000044: 13,2000                                           BANK                                           
047462,000045: 
047463,000046: 13,2351                                           COUNT*   $$/LT-LG                              
047464,000047: 13,2351  E4,1431                                  EBANK=   ALPHAV                                
047465,000048: 13,2351           40220        LAT-LONG           STQ      SETPD                                 
047466,000049: 13,2352           03674                                    INCORPEX                              
047467,000050: 13,2353           00001                                    0D                                    
047468,000051: 13,2354           24007                           STOVL    6D                                    #  SAVE TIME IN 6-7D FOR R-TO-RP
047469,000052: 13,2355           02032                                    ALPHAV                                
047470,000053: 13,2356           51406                           PUSH     ABVAL                                 #  0-5D= R FOR R-TO-RP
047471,000054: 13,2357           16070                           STODL    ALPHAM                                #  ABS. VALUE OF R FOR ALT FORMULA BELOW
047472,000055: 13,2360           24007                                    ZEROVEC                               #  SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
047473,000056: 13,2361           71414                           BOFF     COS                                   #  USE COS(0) TO GET NON-ZERO IN MPAC
047474,000057: 13,2362           01743                                    LUNAFLAG                              #  0=EARTH, 1=MOON
047475,000058: 13,2363           26364                                    CALLRTRP                              
047476,000059: 13,2364           77624        CALLRTRP           CALL                                           
047477,000060: 13,2365           51670                                    R-TO-RP                               #  RP VECTOR CONVERTED FROM R B-29
047478,000061: 13,2366           77656                           UNIT                                           #  UNIT RP B-1
047479,000062: 13,2367           36032                           STCALL   ALPHAV                                #  U2= 1/2 SINL FOR SETRE SUBR BELOW
047480,000063: 13,2370           26550                                    SETGAMMA                              #        SET GAMMA=B2/A2 FOR EARTH, =1 FOR MOON
047481,000064: 13,2371           77624                           CALL                                           #        SCALED B-1
047482,000065: 13,2372           26560                                    SETRE                                 #  CALC RE METERS B-29
047483,000066: 13,2373           63545                           DLOAD    DSQ                                   
047484,000067: 13,2374           02032                                    ALPHAV                                
047485,000068: 13,2375           63525                           PDDL     DSQ                                   
047486,000069: 13,2376           02034                                    ALPHAV     +2                         
047487,000070: 13,2377           75415                           DAD      SQRT                                  

Page 1134

047489,000072: 13,2400           76405                           DMP      SL1R                                  
047490,000073: 13,2401           00011                                    GAMRP                                 
047491,000074: 13,2402           14021                           STODL    COSTH                                 #  COS(LAT) B-1
047492,000075: 13,2403           02036                                    ALPHAV     +4                         
047493,000076: 13,2404           34023                           STCALL   SINTH                                 #  SIN(LAT) B-1
047494,000077: 13,2405           26510                                    ARCTAN                                
047495,000078: 13,2406           15121                           STODL    LAT                                   #  LAT B0
047496,000079: 13,2407           02032                                    ALPHAV                                
047497,000080: 13,2410           14021                           STODL    COSTH                                 #  COS(LONG) B-1
047498,000081: 13,2411           02034                                    ALPHAV     +2                         
047499,000082: 13,2412           34023                           STCALL   SINTH                                 #  SIN(LONG) B-1
047500,000083: 13,2413           26510                                    ARCTAN                                
047501,000084: 13,2414           15123                           STODL    LONG                                  #  LONG. REVS B-0 IN RANGE -1/2 TO 1/2
047502,000085: 13,2415           02070                                    ALPHAM                                
047503,000086: 13,2416           77625                           DSU                                            #  ALT= R-RE METERS B-29
047504,000087: 13,2417           03673                                    ERADM                                 
047505,000088: 13,2420           35125                           STCALL   ALT                                   #  EXIT WITH ALT METERS B-29
047506,000089: 13,2421           03674                                    INCORPEX                              

Page 1135

047508,000091:                                                                                                  #  SUBROUTINE TO CONVERT LAT,LONG,ALT AT GIVEN TIME TO RADIUS VECTOR
047509,000092: 
047510,000093:                                                                                                  #  CALLING SEQUENCE
047511,000094:                                                                                                  #        L-1     CALL
047512,000095:                                                                                                  #        L               LALOTORV
047513,000096: 
047514,000097:                                                                                                  #  SUBROUTINES USED
047515,000098:                                                                                                  #        SETGAMMA, SETRE, RP-TO-R
047516,000099: 
047517,000100:                                                                                                  #  ERASABLE INIT. REQ.
047518,000101:                                                                                                  #        AXO, AYO, AZO, TEPHEM SET AT LAUNCH TIME
047519,000102:                                                                                                  #        LAT -- LATITUDE         (REVS B0)
047520,000103:                                                                                                  #        LONG -- LONGITUDE       (REVS B0)
047521,000104:                                                                                                  #        ALT -- ALTITUDE         (METERS) B-29
047522,000105:                                                                                                  #        MPAC -- TIME            (CSECS B-28)
047523,000106:                                                                                                  #        ERADFLAG =1 TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047524,000107:                                                                                                  #        LUNAFLAG=0 FOR EARTH, 1 FOR MOON
047525,000108: 
047526,000109:                                                                                                  #  OUTPUT
047527,000110:                                                                                                  #        R-VECTOR IN ALPHAV      (METERS B-29)
047528,000111: 
047529,000112: 13,2422           40220        LALOTORV           STQ      SETPD                                 #  LAT,LONG,ALT TO R VECTOR
047530,000113: 13,2423           03674                                    INCORPEX                              
047531,000114: 13,2424           00001                                    0D                                    
047532,000115: 13,2425           34007                           STCALL   6D                                    #  6-7D= TIME FOR RP-TO-R
047533,000116: 13,2426           26550                                    SETGAMMA                              #  GAMMA=B2/A2 FOR EARTH, 1 FOR MOON B-1
047534,000117: 13,2427           73545                           DLOAD    SIN                                   #                COS(LONG)COS(LAT) IN MPAC
047535,000118: 13,2430           01121                                    LAT                                   #      UNIT RP = SIN(LONG)COS(LAT)    2-3D
047536,000119: 13,2431           65275                           DMPR     PDDL                                  #  PD 2          GAMMA*SIN(LAT)       0-1D
047537,000120: 13,2432           00011                                    GAMRP                                 
047538,000121: 13,2433           01121                                    LAT                                   #         0-1D = GAMMA*SIN(LAT) B-2
047539,000122: 13,2434           65346                           COS      PDDL                                  #  PD4    2-3D = COS(LAT) B-1 TEMPORARILY
047540,000123: 13,2435           01123                                    LONG                                  
047541,000124: 13,2436           57356                           SIN      DMPR                                  #  PD 2
047542,000125: 13,2437           71525                           PDDL     COS                                   #  PD 4   2-3D = SIN(LONG)COS(LAT) B-2
047543,000126: 13,2440           01121                                    LAT                                   
047544,000127: 13,2441           71525                           PDDL     COS                                   #  PD 6   4-5D = COS(LAT) B-1 TEMPORARILY
047545,000128: 13,2442           01123                                    LONG                                  
047546,000129: 13,2443           55475                           DMPR     VDEF                                  #  PD 4   MPAC = COS(LONG)COS(LAT) B-2
047547,000130: 13,2444           41456                           UNIT     PUSH                                  #  0-5D= UNIT RP FOR RP-TO-R SUBR.
047548,000131: 13,2445           36032                           STCALL   ALPHAV                                #  ALPHAV +4= SINL FOR SETRE SUBR.
047549,000132: 13,2446           26560                                    SETRE                                 #  RE METERS B-29
047550,000133: 13,2447           43145                           DLOAD    BOFF                                  #  SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
047551,000134: 13,2450           24007                                    ZEROVEC                               
047552,000135: 13,2451           01743                                    LUNAFLAG                              
047553,000136: 13,2452           26454                                    CALLRPRT                              
047554,000137: 13,2453           77746                           COS                                            #  USE COS(0) TO GET NON-ZERO IN MPAC
047555,000138: 13,2454           77624        CALLRPRT           CALL                                           
047556,000139: 13,2455           55716                                    RP-TO-R                               #  EXIT WITH UNIT R VECTOR IN MPAC
047557,000140: 13,2456           16032                           STODL    ALPHAV                                
047558,000141: 13,2457           03673                                    ERADM                                 

Page 1136

047560,000143: 13,2460           74215                           DAD      VXSC                                  #  (RE + ALT)(UNIT R) METERS B-30
047561,000144: 13,2461           01125                                    ALT                                   
047562,000145: 13,2462           02032                                    ALPHAV                                
047563,000146: 13,2463           77772                           VSL1                                           #  R METERS B-29
047564,000147: 13,2464           36032                           STCALL   ALPHAV                                #  EXIT WITH R IN METERS B-29
047565,000148: 13,2465           03674                                    INCORPEX                              
047566,000149: 
047567,000150:                                                                                                  #  SUBROUTINE TO COMPUTE EARTH RADIUS
047568,000151: 
047569,000152:                                                                                                  #  INPUT
047570,000153:                                                                                                  #        1/2 SIN LAT IN ALPHAV +4
047571,000154: 
047572,000155:                                                                                                  #  OUTPUT
047573,000156:                                                                                                  #        EARTH RADIUS IN ERADM AND MPAC (METERS B-29)
047574,000157: 
047575,000158: 13,2466           63545        GETERAD            DLOAD    DSQ                                   
047576,000159: 13,2467           02036                                    ALPHAV     +4                         #  SIN**2(L)
047577,000160: 13,2470           44352                           SL1      BDSU                                  
047578,000161: 13,2471           24005                                    DP1/2                                 #  COS**2(L)
047579,000162: 13,2472           44275                           DMPR     BDSU                                  
047580,000163: 13,2473           26507                                    EE                                    
047581,000164: 13,2474           24005                                    DP1/2                                 
047582,000165: 13,2475           75465                           BDDV     SQRT                                  
047583,000166: 13,2476           26503                                    B2XSC                                 
047584,000167: 13,2477           77622                           SR4R                                           
047585,000168: 13,2500           03673                           STORE    ERADM                                 
047586,000169: 13,2501           77616                           RVQ                                            
047587,000170: 
047588,000171:                                                                                                  #  THE FOLLOWING CONSTANTS WERE COMPUTED WITH A=6378166, B=6356784 METERS
047589,000172:                                                                                                  #  B2XSC = B**2 SCALED B-51
047590,000173:                                                                                                  #  B2/A2 = B**2/A**2 SCALED B-1
047591,000174:                                                                                                  #  EE = (1-B**2/A**2) SCALED B-0
047592,000175: 
047593,000176: 13,2502           00446 00305  B2XSC              2DEC     .0179450689                            #  B**2 SCALED B-51
047594,000177: 13,2504  12,2004               DP1/2              =        XUNIT                                 
047595,000178: 13,2504           17711 05254  B2/A2              2DEC     .9933064884 B-1                        #  GAMMA= B**2/A**2 B-1
047596,000179: 13,2506           00155 25250  EE                 2DEC     6.6935116  E-3                        #  (1-B**2/A**2) B-0
047597,000180: 

Page 1137

047599,000182:                                                                                                  #  ARCTAN SUBROUTINE
047600,000183: 
047601,000184:                                                                                                  #  CALLING SEQUENCE
047602,000185:                                                                                                  #        SIN THETA IN SINTH B-1
047603,000186:                                                                                                  #        COS THETA IN COSTH B-1
047604,000187:                                                                                                  #        CALL ARCTAN
047605,000188: 
047606,000189:                                                                                                  #  OUTPUT
047607,000190:                                                                                                  #        ARCTAN THETA IN MPAC AND THETA B-0 IN RANGE -1/2 TO +1/2
047608,000191: 
047609,000192: 13,2510           77600        ARCTAN             BOV                                            
047610,000193: 13,2511           26512                                    CLROVFLW                              
047611,000194: 13,2512           63545        CLROVFLW           DLOAD    DSQ                                   
047612,000195: 13,2513           00023                                    SINTH                                 
047613,000196: 13,2514           63525                           PDDL     DSQ                                   
047614,000197: 13,2515           00021                                    COSTH                                 
047615,000198: 13,2516           77615                           DAD                                            
047616,000199: 13,2517           75454                           BZE      SQRT                                  
047617,000200: 13,2520           26536                                    ARCTANXX                              #  ATAN=0/0  SET THETA=0
047618,000201: 13,2521           40065                           BDDV     BOV                                   
047619,000202: 13,2522           00023                                    SINTH                                 
047620,000203: 13,2523           26543                                    ATAN=90                               
047621,000204: 13,2524           67542                           SR1      ASIN                                  
047622,000205: 13,2525           00025                           STORE    THETA                                 
047623,000206: 13,2526           50125                           PDDL     BMN                                   
047624,000207: 13,2527           00021                                    COSTH                                 
047625,000208: 13,2530           26532                                    NEGCOS                                
047626,000209: 13,2531           43545                           DLOAD    RVQ                                   
047627,000210: 13,2532           57545        NEGCOS             DLOAD    DCOMP                                 
047628,000211: 13,2533           43244                           BPL      DAD                                   
047629,000212: 13,2534           26540                                    NEGOUT                                
047630,000213: 13,2535           24005                                    DP1/2                                 
047631,000214: 13,2536           00025        ARCTANXX           STORE    THETA                                 
047632,000215: 13,2537           77616                           RVQ                                            
047633,000216: 
047634,000217: 13,2540           52025        NEGOUT             DSU      GOTO                                  
047635,000218: 13,2541           24005                                    DP1/2                                 
047636,000219: 13,2542           26536                                    ARCTANXX                              
047637,000220: 13,2543           75345        ATAN=90            DLOAD    SIGN                                  
047638,000221: 13,2544           11037                                    LODP1/4                               
047639,000222: 13,2545           00023                                    SINTH                                 
047640,000223: 13,2546           00025                           STORE    THETA                                 
047641,000224: 13,2547           77616                           RVQ                                            
047642,000225: 
047643,000226: 13,2550  12,2006               2DZERO             =        DPZERO                                
047644,000227: 

Page 1138

047646,000229:                                                                                                  #  ..... SETGAMMA SUBROUTINE .....
047647,000230:                                                                                                  #  SUBROUTINE TO SET GAMMA FOR THE LAT-LONG AND LALOTORV SUBROUTINES
047648,000231: 
047649,000232:                                                                                                  #  GAMMA = B**2/A**2 FOR EARTH (B-1)
047650,000233:                                                                                                  #  GAMMA = 1 FOR MOON (B-1)
047651,000234: 
047652,000235:                                                                                                  #  CALLING SEQUENCE
047653,000236:                                                                                                  #        L       CALL
047654,000237:                                                                                                  #        L+1             SETGAMMA
047655,000238: 
047656,000239:                                                                                                  #  INPUT
047657,000240:                                                                                                  #        LUNAFLAG=0 FOR EARTH, =1 FOR MOON
047658,000241: 
047659,000242:                                                                                                  #  OUTPUT
047660,000243:                                                                                                  #        GAMMA IN GAMRP (B-1)
047661,000244: 
047662,000245: 13,2550           43145        SETGAMMA           DLOAD    BOFF                                  #  BRANCH FOR EARTH
047663,000246: 13,2551           26505                                    B2/A2                                 #  EARTH GAMMA
047664,000247: 13,2552           01743                                    LUNAFLAG                              
047665,000248: 13,2553           26556                                    SETGMEX                               
047666,000249: 13,2554           77735                           SLOAD                                          
047667,000250: 13,2555           24005                                    1B1                                   #  MOON GAMMA
047668,000251: 13,2556           00011        SETGMEX            STORE    GAMRP                                 
047669,000252: 13,2557           77616                           RVQ                                            
047670,000253: 13,2560                        GAMRP              =        8D                                    
047671,000254: 

Page 1139

047673,000256:                                                                                                  #  ..... SETRE SUBROUTINE .....
047674,000257:                                                                                                  #  SUBROUTINE TO SET RE (EARTH OR MOON RADIUS)
047675,000258: 
047676,000259:                                                                                                  #        RE = RM FOR MOON
047677,000260:                                                                                                  #        RE = RREF FOR FIXED EARTH RADIUS OR COMPUTED RF FOR FISCHER ELLIPSOID
047678,000261: 
047679,000262:                                                                                                  #  CALLING SEQUENCE
047680,000263:                                                                                                  #        L       CALL
047681,000264:                                                                                                  #        L+1             SETRE
047682,000265: 
047683,000266:                                                                                                  #  SUBROUTINES USED
047684,000267:                                                                                                  #        GETERAD
047685,000268: 
047686,000269:                                                                                                  #  INPUT
047687,000270:                                                                                                  #        ERADFLAG = 0 FOR FIXED RE, 1 FOR COMPUTED RE
047688,000271:                                                                                                  #        ALPHAV +4 = 1/2 SINL IF GETERAD IS CALLED
047689,000272:                                                                                                  #        LUNAFLAG = 0 FOR EARTH, =1 FOR MOON
047690,000273: 
047691,000274:                                                                                                  #  OUTPUT
047692,000275:                                                                                                  #        ERADM = 504RM FOR MOON (METERS B-29)
047693,000276:                                                                                                  #        ERADM = ERAD OR COMPUTED RF FOR EARTH (METERS B-29)
047694,000277: 
047695,000278: 13,2560           71220        SETRE              STQ      DLOAD                                 
047696,000279: 13,2561           00051                                    SETREX                                
047697,000280: 13,2562           10003                                    504RM                                 
047698,000281: 13,2563           71214                           BON      DLOAD                                 #  BRANCH FOR MOON
047699,000282: 13,2564           01703                                    LUNAFLAG                              
047700,000283: 13,2565           26575                                    TSTRLSRM                              
047701,000284: 13,2566           10001                                    ERAD                                  
047702,000285: 13,2567           45014                           BOFF     CALL                                  #  ERADFLAG=0 FOR FIXED RE, 1 FOR COMPUTED
047703,000286: 13,2570           00742                                    ERADFLAG                              
047704,000287: 13,2571           26573                                    SETRXX                                
047705,000288: 13,2572           26466                                    GETERAD                               
047706,000289: 13,2573           37673        SETRXX             STCALL   ERADM                                 #  EXIT WITH RE OR RM METERS B-29
047707,000290: 13,2574           00051                                    SETREX                                
047708,000291: 13,2575           77214        TSTRLSRM           BON      VLOAD                                 #  ERADFLAG=0, SET R0=RLS
047709,000292: 13,2576           00702                                    ERADFLAG                              #          =1      R0=RM
047710,000293: 13,2577           26573                                    SETRXX                                
047711,000294: 13,2600           02023                                    RLS                                   
047712,000295: 13,2601           64446                           ABVAL    SR2R                                  #  SCALE FROM B-27 TO B-29
047713,000296: 13,2602           77650                           GOTO                                           
047714,000297: 13,2603           26573                                    SETRXX                                
047715,000298: 13,2604  0000051               SETREX             =        S2                                    
047716,000299: 
047717,000300: 

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