Source Code
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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! |
047428,000002: ## Copyright: Public domain.
047429,000003: ## Filename: LATITUDE_LONGITUDE_SUBROUTINES.agc
047430,000004: ## Purpose: Part of the source code for Luminary 1A build 099.
047431,000005: ## It is part of the source code for the Lunar Module's (LM)
047432,000006: ## Apollo Guidance Computer (AGC), for Apollo 11.
047433,000007: ##
047434,000008: ## Assembler: yaYUL
047435,000009: ## Contact: Jim Lawton <jim DOT lawton AT gmail DOT com>
047436,000010: ## Website: www.ibiblio.org/apollo.
047437,000011: ## Pages: 1133-1139
047438,000012: ## Mod history: 2009-05-28 JL Updated from page images.
047439,000013: ## 2011-01-06 JL Fixed interpretive indentation.
047440,000014: ## 2016-12-17 RSB Proofed text comments with octopus/ProoferComments
047441,000015: ## and corrected the errors found.
047442,000016: ## 2017-03-03 RSB Snapshot of Luminary 99 Rev 1.
047443,000017: ## 2017-03-15 RSB Comment-text fixes identified in 5-way
047444,000018: ## side-by-side diff of Luminary 69/99/116/131/210.
047445,000019:
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Page 1133 |
047447,000021: # SUBROUTINE TO CONVERT RAD VECTOR AT GIVEN TIME TO LAT,LONG AND ALT
047448,000022:
047449,000023: # CALLING SEQUENCE
047450,000024: # L-1 CALL
047451,000025: # L LAT-LONG
047452,000026:
047453,000027: # SUBROUTINES USED
047454,000028: # R-TO-RP, ARCTAN, SETGAMMA, SETRE
047455,000029:
047456,000030: # ERASABLE INIT. REQ.
047457,000031: # AXO, -AYO, AZO, TEPHEM (SET AT LAUNCH TIME)
047458,000032: # ALPHAV = POSITION VECTOR METERS B-29
047459,000033: # MPAC -- TIME (CSECS B-28)
047460,000034: # ERADFLAG =1, TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047461,000035: # LUNAFLAG=0 FOR EARTH, 1 FOR MOON
047462,000036:
047463,000037: # OUTPUT
047464,000038: # LATITUDE IN LAT (REVS. B-0)
047465,000039: # LONGITUDE IN LONG (REVS. B-0)
047466,000040: # ALTITUDE IN ALT METERS B-29
047467,000041:
047468,000042: 30,3775 BANK 30
047469,000043: 13,2000 SETLOC LATLONG
047470,000044: 13,2000 BANK
047471,000045:
047472,000046: 13,2351 COUNT* $$/LT-LG
047473,000047: 13,2351 E4,1431 EBANK= ALPHAV
047474,000048: 13,2351 40220 LAT-LONG STQ SETPD
047475,000049: 13,2352 03674 INCORPEX
047476,000050: 13,2353 00001 0D
047477,000051: 13,2354 24007 STOVL 6D # SAVE TIME IN 6-7D FOR R-TO-RP
047478,000052: 13,2355 02032 ALPHAV
047479,000053: 13,2356 51406 PUSH ABVAL # 0-5D= R FOR R-TO-RP
047480,000054: 13,2357 16070 STODL ALPHAM # ABS. VALUE OF R FOR ALT FORMULA BELOW
047481,000055: 13,2360 24007 ZEROVEC # SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
047482,000056: 13,2361 71414 BOFF COS # USE COS(0) TO GET NON-ZERO IN MPAC
047483,000057: 13,2362 01743 LUNAFLAG # 0=EARTH, 1=MOON
047484,000058: 13,2363 26364 CALLRTRP
047485,000059: 13,2364 77624 CALLRTRP CALL
047486,000060: 13,2365 51670 R-TO-RP # RP VECTOR CONVERTED FROM R B-29
047487,000061: 13,2366 77656 UNIT # UNIT RP B-1
047488,000062: 13,2367 36032 STCALL ALPHAV # U2= 1/2 SINL FOR SETRE SUBR BELOW
047489,000063: 13,2370 26550 SETGAMMA # SET GAMMA=B2/A2 FOR EARTH, =1 FOR MOON
047490,000064: 13,2371 77624 CALL # SCALED B-1
047491,000065: 13,2372 26560 SETRE # CALC RE METERS B-29
047492,000066: 13,2373 63545 DLOAD DSQ
047493,000067: 13,2374 02032 ALPHAV
047494,000068: 13,2375 63525 PDDL DSQ
047495,000069: 13,2376 02034 ALPHAV +2
047496,000070: 13,2377 75415 DAD SQRT
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Page 1134 |
047498,000072: 13,2400 76405 DMP SL1R
047499,000073: 13,2401 00011 GAMRP
047500,000074: 13,2402 14021 STODL COSTH # COS(LAT) B-1
047501,000075: 13,2403 02036 ALPHAV +4
047502,000076: 13,2404 34023 STCALL SINTH # SIN(LAT) B-1
047503,000077: 13,2405 26510 ARCTAN
047504,000078: 13,2406 15121 STODL LAT # LAT B0
047505,000079: 13,2407 02032 ALPHAV
047506,000080: 13,2410 14021 STODL COSTH # COS(LONG) B-1
047507,000081: 13,2411 02034 ALPHAV +2
047508,000082: 13,2412 34023 STCALL SINTH # SIN(LONG) B-1
047509,000083: 13,2413 26510 ARCTAN
047510,000084: 13,2414 15123 STODL LONG # LONG. REVS B-0 IN RANGE -1/2 TO 1/2
047511,000085: 13,2415 02070 ALPHAM
047512,000086: 13,2416 77625 DSU # ALT= R-RE METERS B-29
047513,000087: 13,2417 03673 ERADM
047514,000088: 13,2420 35125 STCALL ALT # EXIT WITH ALT METERS B-29
047515,000089: 13,2421 03674 INCORPEX
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Page 1135 |
047517,000091: # SUBROUTINE TO CONVERT LAT,LONG,ALT AT GIVEN TIME TO RADIUS VECTOR
047518,000092:
047519,000093: # CALLING SEQUENCE
047520,000094: # L-1 CALL
047521,000095: # L LALOTORV
047522,000096:
047523,000097: # SUBROUTINES USED
047524,000098: # SETGAMMA, SETRE, RP-TO-R
047525,000099:
047526,000100: # ERASABLE INIT. REQ.
047527,000101: # AXO, AYO, AZO, TEPHEM SET AT LAUNCH TIME
047528,000102: # LAT -- LATITUDE (REVS B0)
047529,000103: # LONG -- LONGITUDE (REVS B0)
047530,000104: # ALT -- ALTITUDE (METERS) B-29
047531,000105: # MPAC -- TIME (CSECS B-28)
047532,000106: # ERADFLAG =1 TO COMPUTE EARTH RADIUS, =0 FOR FIXED EARTH RADIUS
047533,000107: # LUNAFLAG=0 FOR EARTH, 1 FOR MOON
047534,000108:
047535,000109: # OUTPUT
047536,000110: # R-VECTOR IN ALPHAV (METERS B-29)
047537,000111:
047538,000112: 13,2422 40220 LALOTORV STQ SETPD # LAT,LONG,ALT TO R VECTOR
047539,000113: 13,2423 03674 INCORPEX
047540,000114: 13,2424 00001 0D
047541,000115: 13,2425 34007 STCALL 6D # 6-7D= TIME FOR RP-TO-R
047542,000116: 13,2426 26550 SETGAMMA # GAMMA=B2/A2 FOR EARTH, 1 FOR MOON B-1
047543,000117: 13,2427 73545 DLOAD SIN # COS(LONG)COS(LAT) IN MPAC
047544,000118: 13,2430 01121 LAT # UNIT RP = SIN(LONG)COS(LAT) 2-3D
047545,000119: 13,2431 65275 DMPR PDDL # PD 2 GAMMA*SIN(LAT) 0-1D
047546,000120: 13,2432 00011 GAMRP
047547,000121: 13,2433 01121 LAT # 0-1D = GAMMA*SIN(LAT) B-2
047548,000122: 13,2434 65346 COS PDDL # PD4 2-3D = COS(LAT) B-1 TEMPORARILY
047549,000123: 13,2435 01123 LONG
047550,000124: 13,2436 57356 SIN DMPR # PD 2
047551,000125: 13,2437 71525 PDDL COS # PD 4 2-3D = SIN(LONG)COS(LAT) B-2
047552,000126: 13,2440 01121 LAT
047553,000127: 13,2441 71525 PDDL COS # PD 6 4-5D = COS(LAT) B-1 TEMPORARILY
047554,000128: 13,2442 01123 LONG
047555,000129: 13,2443 55475 DMPR VDEF # PD 4 MPAC = COS(LONG)COS(LAT) B-2
047556,000130: 13,2444 41456 UNIT PUSH # 0-5D= UNIT RP FOR RP-TO-R SUBR.
047557,000131: 13,2445 36032 STCALL ALPHAV # ALPHAV +4= SINL FOR SETRE SUBR.
047558,000132: 13,2446 26560 SETRE # RE METERS B-29
047559,000133: 13,2447 43145 DLOAD BOFF # SET MPAC=0 FOR EARTH, NON-ZERO FOR MOON
047560,000134: 13,2450 24007 ZEROVEC
047561,000135: 13,2451 01743 LUNAFLAG
047562,000136: 13,2452 26454 CALLRPRT
047563,000137: 13,2453 77746 COS # USE COS(0) TO GET NON-ZERO IN MPAC
047564,000138: 13,2454 77624 CALLRPRT CALL
047565,000139: 13,2455 55716 RP-TO-R # EXIT WITH UNIT R VECTOR IN MPAC
047566,000140: 13,2456 16032 STODL ALPHAV
047567,000141: 13,2457 03673 ERADM
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Page 1136 |
047569,000143: 13,2460 74215 DAD VXSC # (RE + ALT)(UNIT R) METERS B-30
047570,000144: 13,2461 01125 ALT
047571,000145: 13,2462 02032 ALPHAV
047572,000146: 13,2463 77772 VSL1 # R METERS B-29
047573,000147: 13,2464 36032 STCALL ALPHAV # EXIT WITH R IN METERS B-29
047574,000148: 13,2465 03674 INCORPEX
047575,000149:
047576,000150: # SUBROUTINE TO COMPUTE EARTH RADIUS
047577,000151:
047578,000152: # INPUT
047579,000153: # 1/2 SIN LAT IN ALPHAV +4
047580,000154:
047581,000155: # OUTPUT
047582,000156: # EARTH RADIUS IN ERADM AND MPAC (METERS B-29)
047583,000157:
047584,000158: 13,2466 63545 GETERAD DLOAD DSQ
047585,000159: 13,2467 02036 ALPHAV +4 # SIN**2(L)
047586,000160: 13,2470 44352 SL1 BDSU
047587,000161: 13,2471 24005 DP1/2 # COS**2(L)
047588,000162: 13,2472 44275 DMPR BDSU
047589,000163: 13,2473 26507 EE
047590,000164: 13,2474 24005 DP1/2
047591,000165: 13,2475 75465 BDDV SQRT
047592,000166: 13,2476 26503 B2XSC
047593,000167: 13,2477 77622 SR4R
047594,000168: 13,2500 03673 STORE ERADM
047595,000169: 13,2501 77616 RVQ
047596,000170:
047597,000171: # THE FOLLOWING CONSTANTS WERE COMPUTED WITH A=6378166, B=6356784 METERS
047598,000172: # B2XSC = B**2 SCALED B-51
047599,000173: # B2/A2 = B**2/A**2 SCALED B-1
047600,000174: # EE = (1-B**2/A**2) SCALED B-0
047601,000175:
047602,000176: 13,2502 00446 00305 B2XSC 2DEC .0179450689 # B**2 SCALED B-51
047603,000177: 13,2504 12,2004 DP1/2 = XUNIT
047604,000178: 13,2504 17711 05254 B2/A2 2DEC .9933064884 B-1 # GAMMA= B**2/A**2 B-1
047605,000179: 13,2506 00155 25250 EE 2DEC 6.6935116 E-3 # (1-B**2/A**2) B-0
047606,000180:
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Page 1137 |
047608,000182: # ARCTAN SUBROUTINE
047609,000183:
047610,000184: # CALLING SEQUENCE
047611,000185: # SIN THETA IN SINTH B-1
047612,000186: # COS THETA IN COSTH B-1
047613,000187: # CALL ARCTAN
047614,000188:
047615,000189: # OUTPUT
047616,000190: # ARCTAN THETA IN MPAC AND THETA B-0 IN RANGE -1/2 TO +1/2
047617,000191:
047618,000192: 13,2510 77600 ARCTAN BOV
047619,000193: 13,2511 26512 CLROVFLW
047620,000194: 13,2512 63545 CLROVFLW DLOAD DSQ
047621,000195: 13,2513 00023 SINTH
047622,000196: 13,2514 63525 PDDL DSQ
047623,000197: 13,2515 00021 COSTH
047624,000198: 13,2516 77615 DAD
047625,000199: 13,2517 75454 BZE SQRT
047626,000200: 13,2520 26536 ARCTANXX # ATAN=0/0 SET THETA=0
047627,000201: 13,2521 40065 BDDV BOV
047628,000202: 13,2522 00023 SINTH
047629,000203: 13,2523 26543 ATAN=90
047630,000204: 13,2524 67542 SR1 ASIN
047631,000205: 13,2525 00025 STORE THETA
047632,000206: 13,2526 50125 PDDL BMN
047633,000207: 13,2527 00021 COSTH
047634,000208: 13,2530 26532 NEGCOS
047635,000209: 13,2531 43545 DLOAD RVQ
047636,000210: 13,2532 57545 NEGCOS DLOAD DCOMP
047637,000211: 13,2533 43244 BPL DAD
047638,000212: 13,2534 26540 NEGOUT
047639,000213: 13,2535 24005 DP1/2
047640,000214: 13,2536 00025 ARCTANXX STORE THETA
047641,000215: 13,2537 77616 RVQ
047642,000216:
047643,000217: 13,2540 52025 NEGOUT DSU GOTO
047644,000218: 13,2541 24005 DP1/2
047645,000219: 13,2542 26536 ARCTANXX
047646,000220: 13,2543 75345 ATAN=90 DLOAD SIGN
047647,000221: 13,2544 11037 LODP1/4
047648,000222: 13,2545 00023 SINTH
047649,000223: 13,2546 00025 STORE THETA
047650,000224: 13,2547 77616 RVQ
047651,000225:
047652,000226: 13,2550 12,2006 2DZERO = DPZERO
047653,000227:
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Page 1138 |
047655,000229: # ..... SETGAMMA SUBROUTINE .....
047656,000230: # SUBROUTINE TO SET GAMMA FOR THE LAT-LONG AND LALOTORV SUBROUTINES
047657,000231:
047658,000232: # GAMMA = B**2/A**2 FOR EARTH (B-1)
047659,000233: # GAMMA = 1 FOR MOON (B-1)
047660,000234:
047661,000235: # CALLING SEQUENCE
047662,000236: # L CALL
047663,000237: # L+1 SETGAMMA
047664,000238:
047665,000239: # INPUT
047666,000240: # LUNAFLAG=0 FOR EARTH, =1 FOR MOON
047667,000241:
047668,000242: # OUTPUT
047669,000243: # GAMMA IN GAMRP (B-1)
047670,000244:
047671,000245: 13,2550 43145 SETGAMMA DLOAD BOFF # BRANCH FOR EARTH
047672,000246: 13,2551 26505 B2/A2 # EARTH GAMMA
047673,000247: 13,2552 01743 LUNAFLAG
047674,000248: 13,2553 26556 SETGMEX
047675,000249: 13,2554 77735 SLOAD
047676,000250: 13,2555 24005 1B1 # MOON GAMMA
047677,000251: 13,2556 00011 SETGMEX STORE GAMRP
047678,000252: 13,2557 77616 RVQ
047679,000253: 13,2560 GAMRP = 8D
047680,000254:
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Page 1139 |
047682,000256: # ..... SETRE SUBROUTINE .....
047683,000257: # SUBROUTINE TO SET RE (EARTH OR MOON RADIUS)
047684,000258:
047685,000259: # RE = RM FOR MOON
047686,000260: # RE = RREF FOR FIXED EARTH RADIUS OR COMPUTED RF FOR FISCHER ELLIPSOID
047687,000261:
047688,000262: # CALLING SEQUENCE
047689,000263: # L CALL
047690,000264: # L+1 SETRE
047691,000265:
047692,000266: # SUBROUTINES USED
047693,000267: # GETERAD
047694,000268:
047695,000269: # INPUT
047696,000270: # ERADFLAG = 0 FOR FIXED RE, 1 FOR COMPUTED RE
047697,000271: # ALPHAV +4 = 1/2 SINL IF GETERAD IS CALLED
047698,000272: # LUNAFLAG = 0 FOR EARTH, =1 FOR MOON
047699,000273:
047700,000274: # OUTPUT
047701,000275: # ERADM = 504RM FOR MOON (METERS B-29)
047702,000276: # ERADM = ERAD OR COMPUTED RF FOR EARTH (METERS B-29)
047703,000277:
047704,000278: 13,2560 71220 SETRE STQ DLOAD
047705,000279: 13,2561 00051 SETREX
047706,000280: 13,2562 10003 504RM
047707,000281: 13,2563 71214 BON DLOAD # BRANCH FOR MOON
047708,000282: 13,2564 01703 LUNAFLAG
047709,000283: 13,2565 26575 TSTRLSRM
047710,000284: 13,2566 10001 ERAD
047711,000285: 13,2567 45014 BOFF CALL # ERADFLAG=0 FOR FIXED RE, 1 FOR COMPUTED
047712,000286: 13,2570 00742 ERADFLAG
047713,000287: 13,2571 26573 SETRXX
047714,000288: 13,2572 26466 GETERAD
047715,000289: 13,2573 37673 SETRXX STCALL ERADM # EXIT WITH RE OR RM METERS B-29
047716,000290: 13,2574 00051 SETREX
047717,000291: 13,2575 77214 TSTRLSRM BON VLOAD # ERADFLAG=0, SET R0=RLS
047718,000292: 13,2576 00702 ERADFLAG # =1 R0=RM
047719,000293: 13,2577 26573 SETRXX
047720,000294: 13,2600 02023 RLS
047721,000295: 13,2601 64446 ABVAL SR2R # SCALE FROM B-27 TO B-29
047722,000296: 13,2602 77650 GOTO
047723,000297: 13,2603 26573 SETRXX
047724,000298: 13,2604 0000051 SETREX = S2
047725,000299:
047726,000300:
End of include-file LATITUDE_LONGITUDE_SUBROUTINES.agc. Parent file is MAIN.agc