hp41programs

Overview
 

-These programs combine the second routine listed in "Astronomical Ephemeris(IV)" & the routine listed in "Jovian & Saturnian Satellites"
-There was not enough room to include the positions of the Moon & Pluto.

-These programs may be used with an HP41CV without any module ( 2020 bytes / SIZE 016 ).

-"EPH" calculates the heliocentric & geocentric coordinates of the Sun and the major planets ( referred to the mean ecliptic & equinox of the date )

-"STL" computes the coordinates of Io Europa Ganymede Callisto if flag F10 is clear
  or Mimas Enceladus Tethys Dione Rhea Titan Hyperion if flag F10 is set

-The x-axis coincides with the equator of the planet.
-The center of the Planet is the origin and x , y are measured in equatorial radii.
 

                                     y ( North )
                                      |
                                      |
                                      |
( East ) --------------Jup/Sat------------------ x   ( West )
                                      |
                                      |
                                ( South )
 
 

Program Listing
 
 
 

Data Registers:     •  R00 = t = time in century since 2000/01/01 0h TT      ( Register R00 is to be initialized before executing these programs )
 

                               LBL "EPH" = LBL 10  LBL 01  LBL 02  LBL 04  LBL 05  LBL 06  LBL 07  LBL 08:

                                    R01 = X_Sun       R03 = geocentric longitude   ( deg )        R06 = heliocentric longitude  ( deg )
                                    R02 = Y_Sun       R04 = geocentric latitude      ( deg )        R07 = heliocentric latitude     ( deg )
                                                              R05 = distance Earth-Planet  ( AU )       R08 = distance Sun-Planet    ( AU )

Flags: /
Subroutines: /

                             STL:

                            Io      -    Europa   - Ganymede - Callisto                                                                if  CF 10

                             R01 = x₁        R03 = x₂         R05 = x₃        R07 = x₄
                             R02 = y₁        R04 = y₂         R06 = y₃        R08 = y₄

       or               Mimas  -  Enceladus  -   Tethys  -   Dione    -    Rhea    -    Titan    -   Hyperion         if  SF 10

                             R01 = x₁        R03 = x₂         R05 = x₃        R07 = x₄         R09 = x₅       R11 = x₆         R13 = x₇
                             R02 = y₁        R04 = y₂         R06 = y₃        R08 = y₄         R10 = y₅       R12 = y₆         R14 = y₇

                             R19 =  - sin D_E  where D_E is the planetocentric declination of the Earth.

Flags:    none for   LBL 10  LBL 01  LBL 02  LBL 04  LBL 05  LBL 06  LBL 07  LBL 08:

        STL:             F01  F02  F03  F04 F05  F06  F07
                              Flag nn  is set when the distance Earth-Satellite n  is shorter than the distance Earth-Planet   ( 0 < nn < 8 )

               CF 10  for the Satellites of Jupiter
               SF 10  for the Satellites of Saturn

Subroutines: /
 

-Lines 639 & 1051 are three-byte GTOs
-If you don't have an HP41CX , replace lines 567-568 by  CF 01  CF 02  CF 03  CF 04  CF 05  CF 06  CF 07
 
 

 
      ( 2020 bytes / SIZE 016 )
 
 

-------------------------------------------------------------------------EPH---------------------------------------------------------------------------
 
 
 
 

 
Example:   Calculate the position of the Sun & the major planets on 2020/07/16 at 0h TT
 

   7502  ENTER^  36525  /   STO 00

   •    the Sun    XEQ "EPH" or  XEQ 10   >>>>    Long = 113°942             =  R03                     R01 = X = -0.41247
                                                                 RDN      Lat  =    0                      =  R04         and       R02 = Y = 0.92896
                                                                 RDN     Dist  =  1.01641 AU       =  R05

   •   Mercury    R/S  or   XEQ 01   >>>>    Long =   96°092              =  R03                     R06 = -31°948 = L
                                                       RDN      Lat  =  -3°790               =  R04         and       R07 =  -6°910 = B
                                                       RDN     Dist  =   0.7253 AU       =  R05                     R08 =  0.3985 AU = R

   •     Venus     R/S  or   XEQ 02   >>>>    Long =   72°336              =  R03                      R06 =  -39°509
                                                       RDN      Lat  =  -4°515               =  R04         and       R07 =  -3°042
                                                       RDN     Dist  =  0.4910 AU         =  R05                     R08 =  0.7281 AU

   •     Mars      R/S  or   XEQ 04   >>>>     Long =  10°297               =  R03                      R06 = -35°263
                                                       RDN      Lat  =   -3°495               =  R04         and       R07 =  -1°843
                                                       RDN     Dist  =  0.7302 AU         =  R05                      R08 =  1.3841 AU

   •    Jupiter     R/S  or   XEQ 05   >>>>     Long =  -67°891            =  R03                      R06 =  -67°529
                                                       RDN      Lat  =    -0.332             =  R04         and       R07 =   -0°266
                                                       RDN     Dist  =   4.141 AU         =  R05                      R08 =   5.157 AU

   •   Saturn      R/S  or   XEQ 06   >>>>    Long =  -61°010              =  R03                      R06 =  -61°523
                                                       RDN      Lat  =  -0°228               =  R04         and        R07 =  -0°205
                                                       RDN     Dist  =  8.985 AU          =  R05                       R08 =  9.998 AU

   •  Uranus     R/S  or   XEQ 07     >>>>    Long =   40°330              =  R03                      R06 =  37°505
                                                       RDN      Lat  =   -0°444              =  R04         and       R07 =   -0°450
                                                       RDN     Dist  =  20.051 AU         =  R05                     R08 =  19.788 AU

   •  Neptune   R/S  or   XEQ 08     >>>>    Long =  -9°164                =  R03                      R06 =  -10°795
                                                       RDN      Lat  =  -1°075                =  R04         and       R07 =  -1°054
                                                       RDN     Dist  =  29.353 AU         =  R05                      R08 =  29.920 AU
 
 
 

--------------------------------------------------------------------------STL----------------------------------------------------------------------------
 
 
 
 

    Execution time =  74s   if  CF 10  ( 4 Moons of Jupiter )
    Execution time = 111s  if  SF 10  ( 7 Moons of Saturn )

Example:    On  2004/12/31 at 0h  TT
 

     •  CF 10     JUPITER

        1826  ENTER^   36525   /     STO 00

                  XEQ "STL"        >>>>    x₁ = -4.930     X<>Y     y₁ = 0.155        and in registers  R01 thru R08:

                      Io        -     Europa    -     Ganymede   -    Callisto

                  x₁ = -4.930       x₂ = -4.831         x₃ = -14.514        x₄ = -8.546
                  y₁ =  0.155       y₂ = -0.307         y₃ =  -0.203         y₄ =  -1.077

-Flag F01 is set:  Io is closer to the Earth than Jupiter.
 

     •  SF 10     SATURN

        1826  ENTER^   36525   /     STO 00

                  XEQ "STL"         >>>>    x₁ = -0.287     X<>Y     y₁ = 1.169        and in registers  R01 thru R14:

                    Mimas     -   Enceladus  -     Tethys    -     Dione     -    Rhea      -     Titan     -    Hyperion

                  x₁ = -0.287       x₂ =  3.911         x₃ = 0.781        x₄ = -0.104     x₅ = -8.730       x₆ = 3.579        x₇ = 21.822
                  y₁ =  1.169       y₂ = -0.213         y₃ = 1.777        y₄ =  2.397      y₅ =  0.254       y₆ = 7.335        y₇ = 3.646

-Flags  F01  F03  F04  F05  F06  F07  are set, whence  Mimas, Tethys, Dione, Rhea, Titan and Hyperion are closer to the Earth than Saturn.
 
 

Notes:

-The HP41 must be in DEG mode.

-"STL" uses the synthetic registers M N O to minimize the number of data registers.
-But M N O might be replaced by R16-R17-R18.

-The first line may also be deleted to save a few bytes.

-If you have a TIME module, you could add   HR  24  /   X<>Y  1.012  DDAYS  -  36525  /  STO 00   after line 02
-In this case, place the date in Y-register & the time in X-register before executing "EPH" or "STL"