### FILE="Main.annotation"

## Copyright: Public domain.

## Filename: P51-P53.agc

## Purpose: A section of LUM69 revision 2.

## It is part of the reconstructed source code for the flown

## version of the flight software for the Lunar Module's (LM)

## Apollo Guidance Computer (AGC) for Apollo 10. The code has

## been recreated from a copy of Luminary revsion 069, using

## changes present in Luminary 099 which were described in

## Luminary memos 75 and 78. The code has been adapted such

## that the resulting bugger words exactly match those specified

## for LUM69 revision 2 in NASA drawing 2021152B, which gives

## relatively high confidence that the reconstruction is correct.

## Reference: pp. 925-978

## Assembler: yaYUL

## Contact: Ron Burkey <info@sandroid.org>.

## Website: www.ibiblio.org/apollo/index.html

## Mod history: 2019-07-27 MAS Created from Luminary 69.

## Page 925

# PROGRAM NAME- PROG52 DATE- JAN 9, 1967

# MOD NO- 0 LOG SECTION- P51-P53

# MODIFICATION BY- LONSKE ASSEMBLY- SUNDANCE REV 46

# FUNCTIONAL DESCRIPTION-

# ALIGNS THE IMU TO ONE OF THREE ORIENTATIONS SELECTED BY THE ASTRONAUT. THE PRESENT IMU ORIENTATION IS KNOWN

# AND IS STORED IN REFSMMAT. THE THREE POSSIBLE ORIENTATIONS MAY BE_

# (A) PREFERRED ORIENTATION

# AN OPTIMUM ORIENTATION FOR A PREVIOUSLY CALCULATED MANUEVER. THIS ORIENTATION MUST BE CALCULATED AND

# STORED BY A PREVIOUSLY SELECTED PROGRAM.

# (B) NOMINAL ORIENTATION

#

# X = UNIT ( R )

# -SM

# Y = UNIT (V X R)

# SM

# Z = UNIT (X X Y )

# SM SM SM

# WHERE_

# R = THE GEOCENTRIC RADIUS VECTOR AT TIME T(ALIGN) SELECTED BY THE ASTRONAUT

# -

# V = THE INERTIAL VELOCITY VECTOR AT TIME T(ALIGN) SELECTED BY THE ASTRONAUT

# -

# (C) REFSMMAT ORIENTATION

# (D) LANDING SITE - THIS IS NOT AVAILIBLE IN SUNDANCE

# THIS SELECTION CORRECTS THE PRESENT IMU ORIENTATION. THE PRESENT ORIENTATION DIFFERS FROM THAT TO WHICH IT

# WAS LAST ALIGNED ONLY DUE TO GYRO DRIFT(I.E. NEITHER GIMBAL LOCK NOR IMU POWER INTERRUPTION HAS OCCURED

# SINCE THE LAST ALIGNMENT).

# AFTER A IMU ORIENTATION HAS BEEN SELECTED ROUTINE S52.2 IS OPERATED TO COMPUTE THE GIMBAL ANGLES USING THE

# NEW ORIENTATION AND THE PRESENT VEHICLE ATTITUDE. CAL52A THEN USES THESE ANGLES, STORED IN THETAD,+1,+2, TO

# COARSE ALIGN THE IMU. THE STAR SELECTION ROUTINE, R56, IS THEN OPERATED. IF 2 STARS ARE NOT AVAILABLE AN ALARM

# IS FLASHED TO NOTIFY THE ASTRONAUT. AT THIS POINT THE ASTRONAUT WILL MANUEVER THE VEHICLE AND SELECT 2 STARS

# EITHER MANUALLY OR AUTOMATICALLY. AFTER 2 STARS HAVE BEEN SELECTED THE IMU IS FINE ALIGNED USING ROUTINE R51. IF

# THE RENDEZVOUS NAVIGATION PROCESS IS OPERATING(INDICATED BY RNDVZFLG) P20 IS DISPLAYED. OTHERWISE P00 IS

# REQUESTED.

# CALLING SEQUENCE-

## Page 926

# THE PROGRAM IS CALLED BY THE ASTRONAUT BY DSKY ENTRY.

# SUBROUTINES CALLED-

# 1. FLAGDOWN 7. S52.2 13. NEWMODEX

# 2. R02BOTH 8. CAL53A 14. PRIOLARM

# 3. GOPERF4 9. FLAGUP

# 4. MATMOVE 10. R56

# 5. GOFLASH 11. R51

# 6. S52.3 12. GOPERF3

# NORMAL EXIT MODES-

# EXITS TO ENDOFJOB

# ALARM OR ABORT EXIT MODES-

# NONE

# OUTPUT-

# THE FOLLOWING MAY BE FLASHED ON THE DSKY

# 1. IMU ORIENTATION CODE

# 2. ALARM CODE 215 -PREFERRED IMU ORIENTATION NOT SPECIFIED

# 3. TIME OF NEXT IGNITION

# 4. GIMBAL ANGLES

# 5. ALARM CODE 405 -TWO STARS NOT AVAILABLE

# 6. PLEASE PERFORM P00

# THE MODE DISPLAY MAY BE CHANGED TO 20

# ERASABLE INITIALIZATION REQUIRED-

# PFRATFLG SHOULD BE SET IF A PREFERRED ORIENTATION HAS BEEN COMPUTED.IF IT HAS BEEN COMPUTED IT IS STORED IN

# XSMD,YSMD,ZSMD.

# RNDVZFLG INDICATES WHETHER THE RENDEZVOUS NAVIGATION PROCESS IS OPERATING.

# DEBRIS-

# WORK AREA

BANK 33

SETLOC P50S

BANK

EBANK= BESTI

COUNT* $$/P52

PROG52 TC BANKCALL

CADR R02BOTH # IMU STATUS CHECK

CAF PFRATBIT

MASK FLAGWRD2 # IS PFRATFLG SET?

CCS A

## Page 927

TC P52A # YES

CAF BIT2 # NO

TC P52A +1

P52A CAF BIT1

TS OPTION2

P52B CAF BIT1

TC BANKCALL # FLASH OPTION CODE AND ORIENTATION CODE

CADR GOPERF4R # FLASH V04N06

TC GOTOPOOH

TCF +5 # V33-PROCEED

TC P52B # NEW CODE - NEW ORIENTATION CODE INPUT

TC PHASCHNG # DISPLAY RETURN

OCT 00014

TC ENDOFJOB

CA OPTION2

MASK THREE

INDEX A

TC +1

TC P52T

TC P52H

TC P52T

P52E TC INTPRET

GOTO

P52F

P52T EXTEND

DCA NEG0

DXCH DSPTEM1

CAF V06N34*

TC BANKCALL

CADR GOFLASH

TC GOTOPOOH

TC +2

TC -5

DXCH DSPTEM1

EXTEND

BZMF +2 # IF TIME ZERO OR NEG USE TIME2

TCF +3

EXTEND

DCA TIME2

DXCH TALIGN

P52V CA OPTION2

MASK BIT2

CCS A

TC P52W

TC INTPRET # OPTION 4 - GET LS ORIENTATION

GOTO

P52LS

## Page 928

# START ALIGNMENT

P52W TC INTPRET

DLOAD

TALIGN # PICK UP ALIGN TIME

CALL # COMPUTE NOMINAL IMU

S52.3 # ORIENTATION

P52D CALL # READ VEHICLE ATTITUDE AND

S52.2 # COMPUTE GIMBAL ANGLES

EXIT

CAF V06N22*

TC BANKCALL # DISPLAY GIMBAL ANGLES

CADR GOFLASH

TC GOTOPOOH

TCF COARSTYP # V33-PROCEED, SEE IF GYRO TORQUE COARSE

TC INTPRET # RECYCLE - VEHICLE HAS BEEN MANUEVERED

GOTO

P52D

REGCOARS TC INTPRET

CALL # DO COARSE ALIGN

CAL53A # ROUTINE

SET CLEAR

REFSMFLG

PFRATFLG

P52F CALL

R51

P52OUT EXIT

TC GOTOPOOH

P52H TC INTPRET # PREFERRED OPTION, GO COMPUTE GIMBALS

GOTO

P52D

VB05N09 = V05N09

V06N22* VN 00622

V06N34* VN 634

V06N89* VN 0689

## Page 929

# CHECK FOR GRRO TORQUE COARSE ALIGNMENT

COARSTYP CAF OCT13

TC BANKCALL # DISPLAY V 50N25 WITH COARSE ALIGN OPTION

CADR GOPERF1

TCF GOTOPOOH # V34-TERMIN&OE

TCF REGCOARS # V33-NORMAL COARSE

TC INTPRET # V32-GYRO TORQUE COARSE

VLOAD MXV

XSMD # GET SM(DESIRED) WRT SM(PRESENT)

REFSMMAT

UNIT

STOVL XDC

YSMD

MXV UNIT

REFSMMAT

STOVL YDC

ZSMD

MXV UNIT

REFSMMAT

STCALL ZDC

GYCOARS

GOTO

P52OUT

OCT13 OCT 13

## Page 930

# COMPUTE LANDING ORIENTATION FOR OPTION 4

P52LS SET CLEAR # GET LANDING SITE ORIENTATION

LUNAFLAG

ERADFLAG # TO PICK UP RLS

SETPD VLOAD

0

RLS # PICK UP LANDING SITE VEC IN MF

PDDL PUSH # RLS PD 0-5

TALIGN

CALL

RP-TO-R # TRANS RLS TO REF

VSR2

STODL ALPHAV # INPUT TO LAT-LONG

TALIGN

CALL

LAT-LONG # GET LAT, LONG, AND ALT

DLOAD SR1 # RESCALE LONG TO DEGREES/2

LONG

STODL LANDLONG

ALT

STODL LANDALT # ALT ALREADY AT 2(29) METERS

LAT

STORE LANDLAT

EXIT

LSDISP CAF V06N89* # DISPLAY LAT,LONG/2, ALT

TC BANKCALL

CADR GOFLASH

TCF GOTOPOOH # VB34 TERMINATE

TCF +2 # VB33 PROCEED

TCF LSDISP # VB32 RECYCLE

TC INTPRET

DLOAD SL1

LANDLONG

STODL LONG

LANDALT

STODL ALT

LANDLAT

STODL LAT

TALIGN

CALL

LALOTORV

VLOAD UNIT # COMPUTE LANDING SITE ORIENT (XSMD)

ALPHAV

STCALL XSMD

LSORIENT

GOTO

P52D # NOW GO COMPUTE GIMBAL ANGLES

## Page 931

# NAME -S50 ALIAS LOCSAM

# BY

# VINCENT

# FUNCTION - COMPUTE INPUTS FOR PICAPAR AND PLANET

# DEFINE

#

# U = UNIT( SUN WRT EARTH)

# ES

# U =UNIT( MOON WRT EARTH)

# EM

# R =POSITION VECTOR OF LEM

# L

# R =MEAN DISTANCE (384402KM) BETWEEN EARTH AND MOON

# EM

# P =RATIO R /(DISTANCE SUN TO EARTH) >.00257125

# EM

# R =EQUATORIAL RADIUSS (6378.166KM) OF EARTH

# E

# LOCSAM COMPUTES IN EARTH INFLUENCE

#

# VSUN = U

# ES

# VEARTH = -UNIT( R )

# L

# VMOON = UNIT(R .U - R )

# EM EM L

# CSUN = COS 90

# CEARTH = COS(5 + ARCSIN(R /MAG(R )))

# E L

# CMOON = COS 5

#

# INPUT - TIME IN MPAC

# OUTPUT - LISTED ABOVE

# SUBROUTINES -LSPOS,LEMPREC

# DEBRIS - VAC AREA ,TSIGHT

## Page 932

SETLOC P50S1

BANK

EBANK= XSM

COUNT* $$/LOSAM

S50 = LOCSAM

LOCSAM STQ

QMIN

STCALL TSIGHT

LSPOS

DLOAD

TSIGHT

STCALL TDEC1

LEMPREC

SSP TIX,2

S2

0

MOONCNTR

EARTCNTR VLOAD VXSC

VMOON

RSUBEM

VSL1 VSU

RATT

UNIT

STOVL VMOON

RATT

UNIT VCOMP

STODL VEARTH

RSUBE

CALL

OCCOS

STODL CEARTH

CSS5

STCALL CMOON

ENDSAM

MOONCNTR VLOAD VXSC

VMOON

ROE

BVSU UNIT

VSUN

STOVL VSUN

VMOON

VXSC VAD

RSUBEM

RATT

UNIT VCOMP

STOVL VEARTH

RATT

UNIT VCOMP

## Page 933

STODL VMOON

RSUBM

CALL

OCCOS

STODL CMOON

CSS5

STORE CEARTH

ENDSAM DLOAD

CSSUN

STORE CSUN

GOTO

QMIN

OCCOS DDV SR1

36D

ASIN DAD

5DEGREES

COS SR1

RVQ

CEARTH = 14D

CSUN = 16D

CMOON = 18D

CSS5 2DEC .2490475 # (COS 5)/4

CSSUN 2DEC .125 # (COS 60)/4

5DEGREES 2DEC .013888889 # SCALED IN REVS

## Page 934

# PROGRAM NAME - R56 DATE DEC 20 66

# MOD 1 LOG SECTION P51-P53

# ASSEMBLY SUNDISK REV40

# BY KEN VINCENT

#

# FUNCTION

# THIS PROGRAM READ THE IMU-CDUS AND COMPUTES THE VEHICLE ORIENTATION

# WITH RESPECT TO INERTIAL SPACE. IT THEN COMPUTES THE SHAFT AXIS (SAX)

# WITH RESPECT TO REFERENCE INERTIAL. EACH STAR IN THE CATALOG IS TESTED

# TO DETERMINE IF IT IS OCCULTED BY EITHER THE EARTH,SUN OR MOON. IF A

# STAR IS NOT OCCULTED THEN IT IS PAIRED WITH ALL STAR OF LOWER INDEX.

# THE PAIRED STAR IS TESTED FOR OCCULTATION. PAIRS OF STARS THAT PASS

# THE OCCULTATION TESTS ARE TESTED FOR GOOD SEPARATION.A PAIR OF STARS

# HAVE GOOD SEPERATION IF THE ANGLE BETWEEN THEM IS LESS THAN 100 DEGREES

# AND MORE THAN 50 DEGREES. THOSE PAIRS WITH GOOD SEPARATION

# ARE THEN TESTED TO SEE IF THEY LIE IN CURRENT FIELD OF VIEW.(WITHIN

# 50 DEGREESOF SAX).THE PAIR WITH MAX SEPARATION IS CHOSEN FROM

# THOSE WITH GOOD SEPARATION,AND IN FIELD OF VIEW.

#

# CALLING SEQUENCE

# L TC BANKCALL

# L+1 CADR R56

# L+2 ERROR RETURN - NO STARS IN FIELD OF VIEW

# L+3 NORMAL RETURN

#

# OUTPUT

# BESTI,BESTJ -SINGLE PREC,INTEGERS,STAR NUMBERS TIMES 6

# VFLAG - FLAG BIT SET IMPLIES NO STARS IN FIELD OF VIEW

#

# INITIALIZATION

# 1)A CALL TO LOCSAM MUST BE MADE

#

# DEBRIS

# WORK AREA

# X,Y,ZNB

# SINCDU,COSCDU

# STARAD - STAR +5

R56 = PICAPAR

COUNT* $$/R56

PICAPAR TC MAKECADR

TS QMIN

TC INTPRET

CALL

CDUTRIG

CALL

CALCSMSC

SETPD

0

SET DLOAD # VFLAG = 1

VFLAG

## Page 935

DPZERO

STOVL BESTI

XNB

VXSC PDVL

HALFDP

ZNB

AXT,1 VXSC

228D # X1 = 37 X 6 + 6

HALFDP

VAD

VXM UNIT

REFSMMAT

STORE SAX # SAX = SHAFT AXIS

SSP SSP # S1=S2=6

S1

6

S2

6

PIC1 TIX,1 GOTO # MAJOR STAR

PIC2

PICEND

PIC2 VLOAD* DOT

CATLOG,1

SAX

DSU BMN

CSS33

PIC1

LXA,2

X1

PIC3 TIX,2 GOTO

PIC4

PIC1

PIC4 VLOAD* DOT

CATLOG,2

SAX

DSU BMN

CSS33

PIC3

VLOAD* DOT*

CATLOG,1

CATLOG,2

DSU BPL

CSS40

PIC3

VLOAD* CALL

CATLOG,1

OCCULT

BON

CULTFLAG

PIC1

## Page 936

VLOAD* CALL

CATLOG,2

OCCULT

BON

CULTFLAG

PIC3

STRATGY BONCLR

VFLAG

NEWPAR

XCHX,1 XCHX,2

BESTI

BESTJ

STRAT VLOAD* DOT*

CATLOG,1

CATLOG,2

PUSH BOFINV

VFLAG

STRAT -3

DLOAD DSU

BPL

PIC3

NEWPAR SXA,1 SXA,2

BESTI

BESTJ

GOTO

PIC3

OCCULT MXV BVSU

CULTRIX

CSS

BZE

CULTED

BMN SIGN

CULTED

MPAC +3

BMN SIGN

CULTED

MPAC +5

BMN CLRGO

CULTED

CULTFLAG

QPRET

CULTED SETGO

CULTFLAG

QPRET

CSS = CEARTH

CSS40 2DEC .16070 # COS 50 / 4

CSS33 2DEC .16070 # COS 50 / 4

PICEND BOFF EXIT

## Page 937

VFLAG

PICGXT

TC PICBXT

PICGXT LXA,1 LXA,2

BESTI

BESTJ

VLOAD DOT*

SAX

CATLOG,1

PDVL DOT*

SAX

CATLOG,2

DSU

BPL SXA,1

PICNSWP

BESTJ

SXA,2

BESTI

PICNSWP EXIT

INCR QMIN

PICBXT CA QMIN

TC SWCALL

VPD = 0D

V0 = 6D

V1 = 12D

V2 = 18D

V3 = 24D

DP0 = 30D

DP1 = 32D

## Page 938

# NAME-R51 FINE ALIGN

# FUNCTION-TO ALIGN THE STABLE MEMBER TO REFSMMAT

# CALLING SEQ- CALL R51

# INPUT - REFSMMAT

# OUTPUT- GYRO TORQUE PULSES

# SUBROUTINES -LOCSAM,PICAPAR,R52,R53,R54,R55

COUNT* $$/R51

R51 STQ

QMAJ

R51.1 EXIT

R51C CAF OCT15

TC BANKCALL

CADR GOPERF1

TC GOTOPOOH

TC +2 # V33E

TC R51E # ENTER

TC INTPRET

RTB DAD

LOADTIME

TSIGHT1

CALL

LOCSAM

EXIT

TC BANKCALL

CADR R56

TC R51I

R51F TC R51E

R51I TC ALARM

OCT 405

CAF VB05N09

TC BANKCALL

CADR GOFLASH

TC GOTOPOOH

TC R51E

TC R51C

R51E CAF ZERO

TS STARIND

R51.2 TC INTPRET

R51.3 EXIT

TC PHASCHNG

OCT 05024

OCT 13000

TC INTPRET

CALL

R52 # AOP WILL MAKE CALLS TO SIGHTING

EXIT

TC BANKCALL

CADR AOTMARK

TC BANKCALL

CADR OPTSTALL

## Page 939

TC CURTAINS

CCS STARIND

TCF +2

TC R51.4

TC INTPRET

VLOAD

STARAD +6

STORE STARSAV2

EXIT

TC PHASCHNG

OCT 05024

OCT 13000

TC INTPRET

DLOAD CALL

TSIGHT

PLANET

MXV UNIT

REFSMMAT

STOVL STARAD +6

PLANVEC

MXV UNIT

REFSMMAT

STOVL STARAD

STARSAV1

STOVL 6D

STARSAV2

STCALL 12D

R54 # STAR DATA TEST

BOFF CALL

FREEFLAG

R51K

AXISGEN

CALL

R55 # GYRO TORQUE

CLEAR

PFRATFLG

R51K EXIT

R51P63 CAF OCT14

TC BANKCALL

CADR GOPERF1

TC GOTOPOOH

TC R51C

TC INTPRET

GOTO

QMAJ

R51.4 TC INTPRET

VLOAD

STARAD +6

STORE STARSAV1

DLOAD CALL

## Page 940

TSIGHT

PLANET

STORE PLANVEC

SSP

STARIND

1

GOTO

R51.3

TSIGHT1 2DEC 36000 # 6 MIN TO MARKING

## Page 941

# GYRO TORQUE COARSE ALIGNMENT

GYCOARS STQ CALL

QMAJ

CALCGTA

CLEAR CLEAR

DRIFTFLG

REFSMFLG

EXIT

CAF V16N20 # MONITOR GIMBALS

TC BANKCALL

CADR GODSPR

CA R55CDR

TC BANKCALL

CADR IMUPULSE

TC BANKCALL

CADR IMUSTALL

TC CURTAINS

TC PHASCHNG

OCT 05024

OCT 13000

TC INTPRET

AXC,1 AXC,2

XSMD

REFSMMAT

CALL # STORE DESIRED REFSMMAT

MATMOVE

CLEAR SET

PFRATFLG

REFSMFLG

CALL

NCOARSE # SET DRIFT AND INITIALIZE 1/PIPADT

GOTO

R51K

V16N20 VN 1620

## Page 942

# R55 GYRO TORQUE

# FUNCTION-COMPUTE AND SEND GYRO PULSES

# CALLING SEQ- CALL R55

# INPUT- X,Y,ZDC- REFSMMAT WRT PRESENT STABLE MEMBER

# OUTPUT- GYRO PULSES

# SUBROUTINES- CALCGTA,GOFLASH,GODSPR,IMUFINE, IMUPULSE,GOPERF1

COUNT* $$/R55

R55 STQ

QMIN

CALL

CALCGTA

PULSEM EXIT

R55.1 CAF V06N93

TC BANKCALL

CADR GOFLASH

TC GOTOPOOH

TC R55.2

TC R55RET

R55.2 TC PHASCHNG

OCT 00214

CA R55CDR

TC BANKCALL

CADR IMUPULSE

TC BANKCALL

CADR IMUSTALL

TC CURTAINS

TC PHASCHNG

OCT 05024

OCT 13000

R55RET TC INTPRET

GOTO

QMIN

V06N93 VN 0693

R55CDR ECADR OGC

R54 = CHKSDATA

# ROUTINE NAME- CHKSDATA DATE- JAN 9, 1967

# MOD NO- 0 LOG SECTION- P51-P53

# MODIFICATION BY- LONSKE ASSEMBLY-

# FUNCTIONAL DESCRIPTION - CHECKS THE VALIDITY OF A PAIR OF STAR SIGHTINGS. WHEN A PAIR OF STAR SIGHTINGS ARE MADE

# BY THE ASTRONAUT THIS ROUTINE OPERATES AND CHECKS THE OBSERVED SIGHTINGS AGAINST STORED STAR VECTORS IN THE

# COMPUTER TO INSURE A PROPER SIGHTING WAS MADE. THE FOLLOWING COMPUTATIONS ARE PERFORMED_

# OS1 = OBSERVED STAR 1 VECTOR

# OS2 = OBSERVED STAR 2 VECTOR

# SS1 = STORED STAR 1 VECTOR

# SS2 = STORED STAR 2 VECTOR

# A1 = ARCCOS(OS1 - OS2)

# A2 = ARCCOS(SS1 - SS2)

# A = ABS(2(A1 - A2))

## Page 943

# THE ANGULAR DIFFERENCE IS DISPLAYED FOR ASTRONAUT ACCEPTENCE

# EXIT MODE 1. FREEFLAG SET IMPLIES ASTRONAUT WANTS TO PROCEED

# 2. FREEFLAG RESET IMPLIES ASTRONAUT WANTS TO RECYCLE ERANCE)

# OUTPUT - 1.VERB 6,NOUN 3- DISPLAYS ANGULAR DIFFERENCE BETWEEN 2 SETS OF STARS.

# 2.STAR VECTORS FROM STAR CATALOG ARE LEFT IN 6D AND 12D.

# ERASABLE INITIALIZATION REQUIRED -

# 1.MARK VECTORS ARE STORED IN STARAD AND STARAD +6.

# 2.CATALOG VECTORS ARE STORED IN 6D AND 12D.

# DEBRIS -

COUNT* $$/R54

CHKSDATA STQ SET

QMIN

FREEFLAG

CHKSAB AXC,1 # SET X1 TO STORE EPHEMERIS DATA

STARAD

CHKSB VLOAD* DOT* # CAL. ANGLE THETA

0,1

6,1

SL1 ACOS

STORE THETA

BOFF INVERT # BRANCH TO CHKSD IF THIS IS 2ND PASS

FREEFLAG

CHKSD

FREEFLAG # CLEAR FREEFLAG

AXC,1 DLOAD # SET X1 TO MARK ANGLES

6D

THETA

STORE 18D

GOTO

CHKSB # RETURN TO CAL. 2ND ANGLE

CHKSD DLOAD DSU

THETA

18D

ABS RTB # COMPUTE POS DIFF

SGNAGREE

STORE NORMTEM1

SET EXIT

FREEFLAG

CAF VB6N5

TC BANKCALL

CADR GOFLASH

TCF GOTOPOOH

TC CHKSDA # PROCEED

TC INTPRET

CLEAR GOTO

FREEFLAG

QMIN

CHKSDA TC INTPRET

## Page 944

GOTO

QMIN

VB6N5 VN 605

# NAME - CAL53A

# FUNCTION -COMPUTE DESIRED GIMBAL ANGLES AND COARSE ALIGN IF NECESSARY

# CALLING SEQUENCE - CALL CAL53A

# INPUT - X,Y,ZSMD ,CDUX,Y,Z

# DESIRED GIMBAL ANGLES - THETAD,+1,+2

# OUTPUT - THE IMU COORDINATES ARE STORED IN REFSMMAT

# SUBROUTINES - S52.2, IMUCOARSE , IMUFINE

COUNT* $$/R50

CAL53A STQ CALL

29D

S52.2 # MAKE ONE FINAL COMP OF GIMBLE ANGLES

RTB SSP

RDCDUS # READ CDUS

S1

1

AXT,1 SETPD

3

4

CALOOP DLOAD* SR1

THETAD +3D,1

PDDL* SR1

4,1

DSU ABS

PUSH DSU

DEGREE1

BMN DLOAD

CALOOP1

DSU BPL

DEG359

CALOOP1

COARFINE CALL

COARSE

CALL

NCOARSE

GOTO

FINEONLY

CALOOP1 TIX,1

CALOOP

FINEONLY AXC,1 AXC,2

XSM

REFSMMAT

CALL

MATMOVE

GOTO

29D

MATMOVE VLOAD* # TRANSFER MATRIX

0,1

## Page 945

STORE 0,2

VLOAD*

6D,1

STORE 6D,2

VLOAD*

12D,1

STORE 12D,2

RVQ

DEGREE1 DEC 46 # 1 DEG SCALED CDU/2

DEG359 DEC 16338 # 359 DEG SCALED CDU/2

RDCDUS INHINT # READ CDUS

CA CDUX

INDEX FIXLOC

TS 1

CA CDUY

INDEX FIXLOC

TS 2

CA CDUZ

INDEX FIXLOC

TS 3

RELINT

TC DANZIG # +

COUNT* $$/INFLT

CALCSMSC AXC,1

XNB

XNBNDX DLOAD DMP

SINCDUY

COSCDUZ

DCOMP

PDDL SR1

SINCDUZ

PDDL DMP

COSCDUY

COSCDUZ

VDEF VSL1

STORE 0,1

DLOAD DMP

SINCDUX

SINCDUZ

SL1

STORE 26D

DMP

SINCDUY

PDDL DMP

COSCDUX

COSCDUY

DSU

PDDL DMP

SINCDUX

## Page 946

COSCDUZ

DCOMP

PDDL DMP

COSCDUX

SINCDUY

PDDL DMP

COSCDUY

26D

DAD VDEF

VSL1

STORE 14,1

VXV* VSL1

0,1

STORE 6,1

RVQ

## Page 947

# NAME - P51 - IMU ORIENTATION DETERMINATION

# MOD.NO.1 23 JAN 67 LOG SECTION - P51-P53

# MOD BY STURLAUGSON ASSEMBLY SUNDANCE REV56

# FUNCTIONAL DESCRIPTION

# DETERMINES THE INERTIAL ORIENTATION OF THE IMU. THE PROGRAM IS SELECTED BY DSKY ENTRY. THE SIGHTING

# (AOTMARK)ROUTINE IS CALLED TO COLLECT AND PROCESS MARKED-STAR DATA. AOTMARK(R53) RETURNS THE STAR NUMBER AND THE

# STAR LOS VECTOR IN STARAD+6. TWO STARS ARE THUS SIGHTED. THE ANGLE BETWEEN THE TWO STARS IS THEN CHECKED AT

# CHKSDATA(R54). REFSMMAT IS THEN COMPUTED AT AXISGEN.

# CALLING SEQUENCE

# THE PROGRAM IS CALLED BY THE ASTRONAUT BY DSKY ENTRY.

# SUBROUTINES CALLED.

# GOPERF3

# GOPERF1

# GODSPR