LUNAR AND SOLAR EPHEMERIDES SUBROUTINES

It name and Comanche 055 page images. of the ephemeral(?) polynomials
# Copyright:    Public domain.
# Filename:     LUNAR_AND_SOLAR_EPHEMERIDES_SUBROUTINES.agc
# Purpose:      Part of the source code for Comanche, build 055. It
#               is part of the source code for the Command Module's
#               (CM) Apollo Guidance Computer (AGC), Apollo 11.
# Assembler:    yaYUL
# Reference:    pp. 785-788
# Contact:      Ron Burkey <info@sandroid.org>
# Website:      http://www.ibiblio.org/apollo.
# Mod history:  2009-05-12 RSB  Adapted from Colossus249 file of the same
#        name and Comanche 055 page images.
#    2009-07-26 RSB  Added annotations related to computation
#        of the ephemeral(?) polynomials.
#
# The contents of the "Comanche055" files, in general, are transcribed
# from scanned documents.
#
#       Assemble revision 055 of AGC program Comanche by NASA
#       2021113-051.  April 1, 1969.
#
#       This AGC program shall also be referred to as Colossus 2A
#
#       Prepared by
#                       Massachusetts Institute of Technology
#                       75 Cambridge Parkway
#                       Cambridge, Massachusetts
#
#       under NASA contract NAS 9-4065.
#
# Refer directly to the online document mentioned above for further
# information.  Please report any errors to info@sandroid.org.

# Page 785
# LUNAR AND SOLAR EPHEMERIDES SUBROUTINES
#
# FUNCTIONAL DESCRIPTION
#
#  THESE SUBROUTINES ARE USED TO DETERMINE THE POSITION AND VELOCITY
#  VECTORS OF THE SUN AND THE MOON RELATIVE TO THE EARTH AT THE
#  SPECIFIED GROUND ELAPSED TIME INPUT BY THE USER.
#
#  THE POSITION OF THE MOON IS STORED IN THE COMPUTER IN THE FORM OF
#  A NINTH DEGREE POLYNOMIAL APPROXIMATION WHICH IS VALID OVER A 15
#  DAY INTERVAL BEGINNING SHORTLY BEFORE LAUNCH.  THEREFORE THE TIME
#  INPUT BY THE USER SHOULD FALL WITHIN THIS 15 DAY INTERVAL.
#
#  LSPOS COMPUTES THE POSITION VECTORS OF THE SUN AND THE MOON.
#
#  LUNPOS COMPUTES THE POSITION VECTOR OF THE MOON.
#
#  LUNVEL COMPUTES THE VELOCITY VECTOR OF THE MOON.
#
#  SOLPOS COMPUTES THE POSITION VECTOR OF THE SUN.
#
# CALLING SEQUENCE
#
#  DLOAD  CALL
#    TIME    GROUND ELAPSED TIME
#    SUBROUTINE  LSPOS OR LUNPOS OR LUNVEL OR SOLPOS
#
# INPUT
#
#  1) SPECIFIED GROUND ELAPSED TIME IN CS x B-28 LOADED IN MPAC.
#
#  2) TIMEMO - TIME AT THE CENTER OF THE RANGE OVER WHICH THE LUNAR
#     POSITION POLYNOMIAL IS VALID IN CS x B-42.
#
#  3) VECOEM - VECTOR COEFFICIENTS OF THE LUNAR POSITION POLYNOMIAL
#     LOADED IN DESCENDING SEQUENCE IN METERS/CS**N x B-2
#
#  4) RESO - POSITION VECTOR OF THE SUN RELATIVE TO THE EARTH AT
#     TIMEMO IN METERS x B-38.
#
#  5) VESO - VELOCITY VECTOR OF THE SUN RELATIVE TO THE EARTH AT
#     TIMEMO IN METERS/CS x B-9.
#
#  6) OMEGAES - ANGULAR VELOCITY OF THE VECTOR RESO AT TIMEMO IN
#     REV/CS x B+26.
#
#  ALL EXCEPT THE FIRST INPUT ARE INCLUDED IN THE PRE-LAUNCH
#  ERASABLE DATA LOAD.
#
# OUTPUT - LSPOS
# Page 786
#  1) 2D OF VAC AREA CONTAINS THE POSITION VECTOR OF THE SUN RELATIVE
#     TO THE EARTH AT TIME INPUT BY THE USER IN METERS x B-38.
#
#  2) MPAC CONTAINS THE POSITION VECTOR OF THE MOON RELATIVE TO THE
#     EARTH AT TIME INPUT BY THE USER IN METERS x B-29.
#
# OUTPUT - LUNPOS
#
#  MPAC CONTAINS THE POSITION VECTOR OF THE MOON RELATIVE TO THE
#  EARTH AT THE TIME INPUT BY USER IN METERS x B-29.
#
# OUTPUT - LUNVEL
#
#  MPAC CONTAINS THE VELOCITY VECTOR OF THE MOON RELATIVE TO THE
#  EARTH AT THE TIME INPUT BY THE USER IN METERS/CS x B-7.
#
# OUTPUT - SOLPOS
#
#  MPAC CONTAINS THE POSITION VECTOR OF THE SUN RELATIVE TO THE EARTH
#  AT TIME INPUT BY THE USER IN METERS x B-38.
#
# SUBROUTINES USED
#
#  NONE
#
# REMARKS
#
#  THE VAC AREA IS USED FOR STORAGE OF INTERMEDIATE AND FINAL RESULTS
#  OF COMPUTATIONS.
#
#  S1, X1 AND X2 ARE USED BY THESE SUBROUTINES.
#  PRELAUNCH ERASABLE DATA LOAD ARE ONLY ERASABLE STORAGE USED BY
#  THESE SUBROUTINES.
#  RESTARTS DURING OPERATION OF THESE SUBROUTINES MUST BE HANDLED BY
#  THE USER.

    BANK  36
    SETLOC  EPHEM
    BANK

    COUNT*  $$/EPHEM
    EBANK=  END-E7
LSPOS    AXT,2      # COMPUTES POSITION VECTORS OF BOTH THE
      RESA    # SUN AND THE MOON.  THE POSITION VECTOR
    AXT,1  GOTO    # OF THE SUN IS STORED IN 2D OF THE VAC
      RES    # AREA.  THE POSITION VECTOR OF THE MOON
      LSTIME    # IS STORED IN MPAC.
LUNPOS    AXT,1  GOTO    # COMPUTES THE POSITION VECTOR OF THE MOON
      REM    # AND STORES IT IN MPAC.
      LSTIME
# Page 787
LUNVEL    AXT,1  GOTO    # COMPUTES THE VELOCITY VECTOR OF THE MOON
      VEM    # AND STORES IT IN MPAC.
      LSTIME
SOLPOS    STQ  AXT,1    # COMPUTES THE POSITION VECTOR OF THE SUN
      X2    # AND STORES IT IN MPAC.
      RES
LSTIME    SETPD  SR
      0D
      14D
    TAD  DCOMP
      TEPHEM
    TAD  DCOMP
      TIMEMO
    SL  SSP
      16D
      S1
      6D
    GOTO
      X1
RES    PUSH  DMP    #          PD- 2
      OMEGAES
    PUSH  COS    #          PD- 4
    VXSC  PDDL    #          PD- 8
      RESO
    SIN  PDVL    #          PD-10
      RESO
    PUSH  UNIT    #          PD-16
    VXV  UNIT
      VESO
    VXV  VSL1    #          PD-10
    VXSC  VAD    #          PD-02
    VSL1  GOTO    # RES IN METERS x B-38 IN MPAC.
      X2
RESA    STODL  2D    # RES IN METERS x B-38 IN 2D OF VAC.  PD- 0
REM    AXT,1  PDVL    #          PD- 2
      54D
      VECOEM
REMA    VXSC  VAD*
      0D
      VECOEM +60D,1
    TIX,1  VSL2    # REM IN METERS x B-29 IN MPAC.
      REMA
    RVQ
VEM    AXT,1  PDDL    #          PD- 2
      48D
      NINEB4
    PUSH  VXSC    #          PD- 4
      VECOEM
VEMA    VXSC
      0D
# Page 788
    STODL  4D    #          PD- 2
    DSU  PUSH    #          PD- 4
      ONEB4
    VXSC*  VAD
      VECOEM +54D,1
      4D
    TIX,1  VSL2    # VEM IN METERS/CS x B-7 IN MPAC.
      VEMA
    RVQ
NINEB4    2DEC  9.0 B-4

ONEB4    2DEC  1.0 B-4