Arithmetical  Operation

15

day  (Table  5);  i  counts  the  transits  of  the  Moon  and  one  only  has  to  bear  In  mind
that  this  numerator  has  the  same  zero  point  both  In  analysis  and  synthesis.
The  following  paragraphs  will  put  the  reader  In  a  position,  If  required,  to
develop  his  or  her  own  computer  programme  for  tidal  analysis  and  synthesis.
The  problem  can  be  roughly  organised  Into  7  steps  a)  to  g):
a)  Calculation  of  passage  times  of  the  true  Moon  over  the  prime  meridian  In
upper  and  lower  culmination,
b)  Synchronisation  of  the  mean  Moon  with  the  transit  times  of  the  true  Moon,
c)  Processing  of  19  years  of  gauge  observations,
d)  Filtering  of  data  (3  standard  deviations),
e)  Determination  of  the  relevant  angular  velocities,
f)  8  or,  respectively,  96  least  square  fits  for  calculating  the  coefficients  and
g)  Synthesis.
a)  Calculation  of  passage  times  of  the  true  Moon
over  the  prime  meridian  in  upper  and  lower
culmination
Here,  the  transit  time  shall  be  defined  as  the  point  In  time  of  the  Moon's  transit
(centre  of  mass)  over  the  prime  meridian  (Greenwich  Observatory).  A  procedure ­
  exact  to  the  minute  can  be  programmed  on  the  basis  of  the  data  given  In
Meeus  (1998),  chapters  7,10,  13,  22,  47.  Alternatively,  one  may  substitute
tables  obtained  from  astronomical  service  providers.  Due  to  the  uncertainty  of
gauge  observations  (see  c)),  It  Is  not  necessary  to  observe  a  high  degree  of
accuracy  In  transit  calculations.