Source Code
042581,000001: # Copyright: Public domain.
042582,000002: # Filename: LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc
042583,000003: # Purpose: Part of the source code for Luminary 1A build 099.
042584,000004: # It is part of the source code for the Lunar Module's (LM)
042585,000005: # Apollo Guidance Computer (AGC), for Apollo 11.
042586,000006: # Assembler: yaYUL
042587,000007: # Contact: Hartmuth Gutsche <hgutsche@xplornet.com>.
042588,000008: # Website: www.ibiblio.org/apollo.
042589,000009: # Pages: 984-987
042590,000010: # Mod history: 2009-05-24 HG Transcribed from page images.
042591,000011:
042592,000012: # This source code has been transcribed or otherwise adapted from
042593,000013: # digitized images of a hardcopy from the MIT Museum. The digitization
042594,000014: # was performed by Paul Fjeld, and arranged for by Deborah Douglas of
042595,000015: # the Museum. Many thanks to both. The images (with suitable reduction
042596,000016: # in storage size and consequent reduction in image quality as well) are
042597,000017: # available online at www.ibiblio.org/apollo. If for some reason you
042598,000018: # find that the images are illegible, contact me at info@sandroid.org
042599,000019: # about getting access to the (much) higher-quality images which Paul
042600,000020: # actually created.
042601,000021:
042602,000022: # Notations on the hardcopy document read, in part:
042603,000023:
042604,000024: # Assemble revision 001 of AGC program LMY99 by NASA 2021112-61
042605,000025: # 16:27 JULY 14, 1969
042606,000026:
042607,000027: # Page 984
042608,000028: # NAME -- LSPOS -- LOCATE SUN AND MOON DATE -- 25 OCT 67
042609,000029: # MOD NO. 1
042610,000030: # MOD BY NEVILLE ASSEMBLY SUNDANCE
042611,000031:
042612,000032: # FUNCTIONAL DESCRIPTION
042613,000033:
042614,000034: # COMPUTES UNIT POSITION VECTOR OF THE SUN AND MOON IN THE BASIC REFERENCE SYSTEM. THE SUN VECTOR S IS
042615,000035: # LOCATED VIA TWO ANGLES. THE FIRST ANGLE (OBLIQUITY) IS THE ANGLE BETWEEN THE EARTH EQUATOR AND THE ECLIPTIC. THE
042616,000036: # POSITION VECTOR OF THE SUN IS
042617,000037: # _
042618,000038: # S = (COS(LOS), COS(OBL)*SIN(LOS), SIN(OBL)*SIN(LOS)), WHERE
042619,000039:
042620,000040: # LOS = LOS +LOS *T-(C *SIN(2PI*T)/365.24 +C *COS(2PI*T)/365.24)
042621,000041: # 0 R 0 1
042622,000042: # LOS (RAD) IS THE LONGITUDE OF THE SUN FOR MIGNIGHT JUNE 30TH OF THE PARTICULAR YEAR.
042623,000043: # 0
042624,000044: # LOS (RAD/DAY) IS THE MEAN RATE FOR THE PARTICULAR YEAR.
042625,000045: # R
042626,000046:
042627,000047: # LOS AND LOS ARE STORED AS LOSC AND LOSR IN RATESP.
042628,000048: # 0 R
042629,000049: # COS(OBL) AND SIN(OBL) ARE STORED IN THE MATRIX KONMAT.
042630,000050:
042631,000051: # T, TIME MEASURED IN DAYS (24 HOURS) IS STORED IN TIMEP.
042632,000052:
042633,000053: # C AND C ARE FUDGE FACTORS TO MINIMIZE THE DEVIATION. THEY ARE STORED AS ONE CONSTANT (CMOD), SINCE
042634,000054: # 0 1 2 2 1/2
042635,000055: # C *SIN(X)+C *COS(X) CAN BE WRITTEN AS (C +C ) *SIN(X+PHI), WHERE PHI=ARCTAN(C /C ).
042636,000056: # 0 1 1 0
042637,000057:
042638,000058: # THE MOON IS LOCATED VIA FOUR ANGLES, THE FIRST IS THE OBLIQUITY. THE SECOND IS THE MEAN LONGITUDE OF THE MOON,
042639,000059: # MEASURED IN THE ECLIPTIC FROM THE MEAN EQUINOX TO THE MEAN ASCENDING NODE OF THE LUNAR ORBIT, AND THEN ALONG THE
042640,000060: # ORBIT. THE THIRD ANGLE IS THE ANGLE BETWEEN THE ECLIPTIC AND THE LUNAR ORBIT. THE FOURTH ANGLE IS THE LONGITUDE
042641,000061: # OF THE NODE OF THE MOON, MEASURED IN THE LUNAR ORBIT. LET THESE ANGLES BE OBL,LOM,IM, AND LON RESPECTIVELY.
042642,000062:
042643,000063: # THE SIMPLIFIED POSITION VECTOR OF THE MOON IS
042644,000064: # _
042645,000065: # 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))
042646,000066:
042647,000067: # WHERE
042648,000068: # 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
042649,000069: # 0 R 0 1 0 1
042650,000070: # LON=LON +LON
042651,000071: # 0 R
042652,000072: # A , A , B AND B ARE STORE AS AMOD AND BMOD (SEE DESCRIPTION OF CMOD, ABOVE). COS(OBL), SIN(OBL)*SIN(IM),
042653,000073: # 0 1 0 1
042654,000074: # SIN(OBL), AND COS(OBL)*SIN(IM) ARE STORED IN KONMAT AS K1, K2, K3, AND K4, RESPECTIVELY. LOM , LOM , LON , LON
042655,000075: # 0 R 0 R
042656,000076: # ARE STORED AS LOM0, LOMR, LON0, AND LONR IN RATESP.
042657,000077:
042658,000078: # THE THREE PHIS ARE STORED AS AARG, BARG, AND CARG(SUN). ALL CONSTANTS ARE UPDATED BY YEAR.
042659,000079:
042660,000080: # CALLING SEQUENCE
042661,000081: # Page 985
042662,000082: # CALL LSPOS. RETURN IS VIA CPRET.
042663,000083:
042664,000084: # ALARMS OR ABORTS
042665,000085: # NONE
042666,000086:
042667,000087: # ERASABLE INITIALIZATION REQUIRED
042668,000088: # TEPHEM -- TIME FROM MIGNIGHT 1 JULY PRECEDING THE LAUNCH TO THE TIME OF THE LAUNCH (WHEN THE AGC CLOCK WENT
042669,000089: # TO ZERO). TEPHEM IS TP WITH UNITS OF CENTI-SECONDS.
042670,000090:
042671,000091: # TIME2 AND TIME1 ARE IN MPAC AND MPAC +1 WHEN PROGRAM IS CALLED.
042672,000092:
042673,000093: # OUTPUT
042674,000094: # UNIT POSITIONAL VECTOR OF SUN IN VSUN. (SCALED B-1)
042675,000095: # UNIT POSITIONAL VECTOR OF MOON IN VMOON. (SCALED B-1)
042676,000096:
042677,000097: # SUBROUTINES USED
042678,000098: # NONE
042679,000099:
042680,000100: # DEBRIS
042681,000101: # CURRENT CORE SET, WORK AREA AND FREEFLAG
042682,000102:
042683,000103: 04,3027 BANK 04
042684,000104: 15,2000 SETLOC EPHEM
042685,000105: 15,2000 BANK
042686,000106:
042687,000107: 15,3664 E5,1714 EBANK= VSUN
042688,000108: 15,3664 COUNT* $$/EPHEM
042689,000109: 15,3664 15,3664 LUNPOS EQUALS LSPOS
042690,000110:
042691,000111: 15,3664 54201 LSPOS SETPD SR
042692,000112: 15,3665 00001 0
042693,000113: 15,3666 20617 14D # TP
042694,000114: 15,3667 56371 TAD DDV
042695,000115: # HG comments in [...] are hand written comments in original listing
042696,000116: 15,3670 01707 TEPHEM # TIME OF LAUNCH [IN CENTISEC B 42]
042697,000117: 15,3671 12024 CSTODAY # 24 HOURS -- 8640000 CENTI-SECS/DAY B-33
042698,000118: 15,3672 00031 STORE TIMEP # T IN DAYS [@ B 9 = 512 DAYS]
042699,000119: 15,3673 77170 AXT,1 AXT,2 # [GRANULRITY = 0.164 SEC]
042700,000120: 15,3674 00000 0
042701,000121: 15,3675 00000 0
042702,000122: 15,3676 77614 CLEAR
042703,000123: 15,3677 00274 FREEFLAG # SWITCH BIT
042704,000124: 15,3700 77745 POSITA DLOAD
042705,000125: 15,3701 12004 KONMAT +2 # ZEROS
042706,000126: 15,3702 00027 STORE GTMP
042707,000127: 15,3703 40745 POSITB DLOAD DMP*
042708,000128: 15,3704 00031 TIMEP # T
042709,000129: 15,3705 12050 VAL67 +4,1 # 1/27 OR 1/32 OR 1/365
042710,000130: # Page 986
042711,000131: 15,3706 42661 SL DAD*
042712,000132: 15,3707 20211 8D
042713,000133: 15,3710 12046 VAL67 +2,1 # AARG
042714,000134: 15,3711 40756 SIN DMP* # SIN(T/27+PHI) OR T/32 OR T/365
042715,000135: 15,3712 12044 VAL67,1 # (A0**2+A1**2)**1/2 SIN(X+PHIA)
042716,000136: 15,3713 62015 DAD INCR,1 # PLUS
042717,000137: 15,3714 00027 GTMP # (B0**2+B1**2)**1/2 SIN(X+PHIB)
042718,000138: 15,3715 77771 DEC -6 B-14
042719,000139: 15,3716 00027 STORE GTMP # OR (C0**2+C1**2)**1/2 SIN(X+PHIC)
042720,000140: 15,3717 77614 BOFSET
042721,000141: 15,3720 00054 FREEFLAG
042722,000142: 15,3721 33703 POSITB
042723,000143: 15,3722 40745 POSITD DLOAD DMP*
042724,000144: 15,3723 00031 TIMEP # T
042725,000145: 15,3724 65747 RATESP,2 # LOMR,LOSR,LONR
042726,000146: 15,3725 42661 SL DAD*
042727,000147: 15,3726 20206 5D
042728,000148: 15,3727 65741 RATESP +6,2 # LOM0,LOS0,LON0
042729,000149: 15,3730 77625 DSU
042730,000150: 15,3731 00027 GTMP
042731,000151: 15,3732 10021 STORE STMP,2 # LOM,LOS,LON
042732,000152: 15,3733 63135 SLOAD INCR,2
042733,000153: 15,3734 00050 X2
042734,000154: 15,3735 77775 DEC -2 B-14
042735,000155: 15,3736 53015 DAD BZE
042736,000156: 15,3737 12026 RCB-13 # PLUS 2
042737,000157: 15,3740 33770 POSITE # 2ND
042738,000158: 15,3741 77644 BPL
042739,000159: 15,3742 33700 POSITA # 1ST
042740,000160: 15,3743 45345 POSITF DLOAD DSU # 3RD
042741,000161: 15,3744 00021 STMP # LOM
042742,000162: 15,3745 00025 STMP +4 # LON
042743,000163: 15,3746 65356 SIN PDDL # SIN(LOM-LON)
042744,000164: 15,3747 00021 STMP
042745,000165: 15,3750 65356 SIN PDDL # SIN LOM
042746,000166: 15,3751 00021 STMP
042747,000167: 15,3752 55546 COS VDEF # COS LOM
042748,000168: 15,3753 53521 MXV UNIT
042749,000169: 15,3754 12002 KONMAT # K1,K2,K3,K4,
042750,000170: 15,3755 02723 STORE VMOON
042751,000171: 15,3756 65345 DLOAD PDDL
042752,000172: 15,3757 12004 KONMAT +2 # ZERO
042753,000173: 15,3760 00023 STMP +2
042754,000174: 15,3761 65356 SIN PDDL # SIN LOS
042755,000175: 15,3762 00023 STMP +2
042756,000176: 15,3763 55546 COS VDEF # COS LOS
042757,000177: 15,3764 53521 MXV UNIT
042758,000178: 15,3765 12002 KONMAT
042759,000179: 15,3766 02715 STORE VSUN
042760,000180: 15,3767 77616 RVQ
042761,000181: # Page 987
042762,000182: 15,3770 77745 POSITE DLOAD
042763,000183: 15,3771 12004 KONMAT +2 # ZEROS
042764,000184: 15,3772 00027 STORE GTMP
042765,000185: 15,3773 77650 GOTO
042766,000186: 15,3774 33722 POSITD
042767,000187: 15,3775 77616 LUNVEL RVQ
042768,000188: 05,2000 SETLOC EPHEM1
042769,000189: 05,2000 BANK
042770,000190:
042771,000191: 05,3506 COUNT* $$/EPHEM
042772,000192: 05,3506 STMP EQUALS 16D
042773,000193: 05,3506 GTMP EQUALS 22D
042774,000194: 05,3506 TIMEP EQUALS 24D
042775,000195:
042776,000196: # *** END OF LEMP50S .115 ***
End of include-file LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc. Parent file is MAIN.agc