r.reasenberg  4/72  subroutine sbexp
extra printout for probe integration
updated 1977  j.f.chandler
additional options added feb. 1979 by rdr and rbg
updated jan 1980 by rdr and kcl
close-approach print added 1989  jfc

flags     if true then
iflg      iout=kout
xflg      print 'x' in km and date
aflg      print 'x' in au and date
dflg      print partials
kflg      print kepler elements
tflg      print apsidal time
bflg      print body vectors
1         earth     s/c
2         earth     center
3         sun       s/c
4         sun       center
5        target     s/c
6         t(1)
7         t(2)
8         t(3)
9         t(4)
lflg      print landmark data
1         lat. and long of s/c w.r.t. central body
2         motion w.r.t. 'stationary' central body
3         lat and long. of s/c wrt central body at apsidal time
clflg     print close approaches: body vector + angles
1         earth-site figure of merit
2         earth
3-14      targets

antenna gain (db) = g0 if zenith angle < lim0
taper to g1 at zenith angle = lim1
zero at greater angles
noise: constant for ZA < lim0', increasing by 10**(-dg) out to lim1
could make this model a set of input parameters

kkp(3) = state
state is a packed-bits number
1  print cartesian state
2  print all partials
4  print apsidal time if near
8  print elliptic elements  standard frame
n.i.
16  print elliptic elements  central body of date
32  print elliptic elements  plane of the sky

kkp(4) = bodys
bodys is a packed-bits number
1  print earth - s/c vector
2  print earth - central body vector
4  print sun - s/c vector
8  print sun - central body vector
16  print target - s/c vector

kkp(5) = lmark
lmark is a packed-bits number
1  print latitude and longitude of s/c w.r.t. central body
2  print projected motion of s/c on  central body
4  print latitude and long. of s/c wrt central body at apsida
time if near

kkp(6) = close
close is a packed-bits number
1     print distance, snr, zenith angle at good approach
2     print vector of s/c w.r.t. earth at close approach
3-14  print vector of s/c w.r.t. target at close approach