Setting the Lunar Landing site

Introduction

As Fabrizio Bernardini describes in (1)
AGC provides correct orbital parameters but these are expressed in distance from the Moon center, instead of being altitudes over the Moon radius (reference is the landing zone radius).

Code Analysis (Luminary)

All analysis is done from Luminary 1C 131 assembly listing output from yaYUL (2).

For calculation the temporary variable RPADTEM is used. 
SUBROUTINE NAME: SR30.1

#  ERASABLE INITIALIZATION REQUIRED --
# 	TFF/RTMU	(+17) EARTH	RECIPROCAL OF PROPER GRAV CONSTANT FOR
# 			(+14) MOON	EARTH OR MOON = 1/SQRT(MU).
# 	RONE		(-29) M		STATE VECTOR
# 	VONE		(-7) M/CS	STATE VECTOR
# 	RPADTEM		(-29) M EARTH	RADIUS OF LAUNCH PAD OR LUNAR LANDING
# 			(-27) M MOON	SITE.
# 	HPERMIN		(-29) M EARTH	(300 OR 35) KFT MINIMUM PERIGEE ALTITUDE
# 			(-27) M MOON	ABOVE LAUNCH PAD OR LUNAR LANDING SITE.
# 	V82EMFLG	(INT SW BIT)	RESET FOR EARTH, SET FOR MOON.
RPADTEM is initialized in different ways depending if earth or moon orbit is set. 
22,3350  02201  STORE    HPERMIN         #  TFFRTMU, HPERMIN, AND RPADTEM ARE ALL
22,3351  46135  SLOAD    BHIZ            #  EARTH/MOON PARAMETERS AS SET HERE.
22,3352  00050           X2              #
22,3353  45367           EARTHPAD        #
22,3354  77650  GOTO                     #
22,3355  45373           MOONPAD         #
For earth orbit RPADTEM is set from the constant RPAD. Since the RPAD constant is set to correct values, all displays in earth orbit should show the expected height over launch pad radius. 
23,2337  00302 17755  RPAD              2DEC     6373338    B-29            #  STANDARD RADIUS OF PAD 37-B.
                                                                            #  = 20 909 901.57 FT
For moon orbit it is calculated from something called RLS vector (3). 
22,3373  51575  MOONPAD  VLOAD    ABVAL  #  COMPUTE MOON PAD RADIUS FROM RLS VECTOR.
22,3374  02023                    RLS    #  SCALED AT (-27)M
The RLS vector is located in erasable memory and is not initialized to the lunar landing site. 
E4,1422               RLS               ERASE    +5                         #  I(6) LANDING SITE VECTOR -- MOON REF

>show E4,1422 + 5
002022 E4,1422 000000 000000 000000 000000 000000 000000

Additional findings

In R-567 Page 103 (4) I found one paragraph which is maybe of note. 
487
P52/LUMINARY

COMPUTE LAT, LONG/2,
AND ALT FROM
STORED LANDING SITE
VECTOR (IN "PRIMARY"
STORAGE) AND SPEC-
IFIED T(ALIGN).
(NOTE: THE "PRIMARY"
STORAGE OF THE LAN-
DING SITE CAN BE
MODIFIED ONLY BY
PRELAUNCH ERASABLE
LOAD, P27, P57 OR
P68.
P68 is overwritting the reference landing site with the actual landing site, which is now known after landing.

Setting the RLS vector to pad radius (simple test)

For a first verification I set the x component of the RLS vector to the (assumed) landing site radius. 
938.50 NM * 1852 m/NM = 1738102.00 m

1738102.00 / 2 ^ 27 = .01294986903667449951

# CheckDec
> .01294986903667449951
00324 05354
To enter the radius as x component of RLS with the DSKY 
V21N02E
F 21 02
2022E
00324E

V21N02E
F 21 02
2023E
05354E
Now V82 show the expected values.

  1. Fabrizio Bernardini
    The quest for correct AGC State Vector propagation and orbital navigation

  2. Ronald Burkey
    Luminary 1C 131 assembly listing output by yaYUL

  3. Apollo Glossary
    RLS Radius of Landing Site or Reference Landing Site

  4. R-567: Guidance System Operations Plan for Manned LM Earth Orbital and Lunar Missions Using Program Luminary 1C (Rev. 131)
    Programs P40 through P67. (130 pages, 2.2M bytes.)

  5. Ronald Burkey
    LM Flight Software (Luminary)

  6. NASA Goddard Space Flight Center
    Apollo Landing Site Coordinates