t.forni  december 1967  subroutine obsred
radar, optic, trnsit are the calling routines
read one record from iiobcn and / or iiabs1 if applicable
set up obscrd labeled common
set up switches for rest of run

mocpar = 0 compar called in midst of least squares iteration
read all three data sets iobcon, iobs, iabs1 which become in
subroutines of compar iiobcn, iiobs, iiabs1
mocpar = 1 compar called at end of least squares iteration to
calculate dummy observations
read only iobcon which become in subroutines of compar iiobcn

ict(79)=-2 dummy observations not calculated each iteration nor
after convergence
ict(79)=-1 dummy observations not calculated each iteration, but are
after convergence
ict(79)= 0 dummy observations calculated each iteration, but not
after convergence
ict(79)= 1 dummy observations calculated each iteration and after
convergence

ict(80)=-1 input observation library tapes not used
ict(80)= 0 input observation library tapes are used, program eats its
tale from iteration to iteration
ict(80)= 1 input observation library tapes only are used to form the
normal equations for first iteration with no computation
of observed minus theory.
subsequent iterations same as ict(80)=0

savb(i,1), i=1,numsav,  saved precession-nutation,etc. from input
observation library tape for radar, optical
and first part of transit observation
savb(i,2), i=1,numsav,  the same quantities read from iiobs
savb(1-8) are set from dstf(2-9) in comrit
savb(1) =dstf(2)= longitude of subradar point
savb(2) =dstf(3)= latitude of subradar point
savb(3) =dstf(4)= time delay from receive to reflection (sec)
savb(4) =dstf(5)= longitude of observed spot away from
subradar spot
-or- time delay to 2nd object
-or- 2nd frequency (hz)
savb(5) =dstf(6)= latitude ofobserved spot away from
subradar point
-or- cumulative obsrvd psr phase (cycles)
savb(6) =dstf(7)= xmitter frequency for vlbi observations (hz)
-or- interstellar freq for psr observations
savb(7) =dstf(8)= topography (2-way elevation in sec) of
observed point
-or- 1-way delay attributable to pulsar orbit
(in sec) to be subtracted from the calculated
delay from the pulsar system center of mass
-or- 2nd xmitter frequency for vlbi (hz)
savb(8) =dstf(9)= instantaneous psr pulse period at reception
savb(9-26)are set from nutprc(1-18)
savb(27)= pc(1) = dpsi*cos(obliq)
for meridian-circle observations (ncodf.ge.4) savb(18-21) have a
different meaning:
savb(18)= salph
savb(19)= calph
savb(20)= tdelt
savb(21)= estf(10)
for transit/occultation data, savb(18-34) are treated differently
savb(18)= plate motion reference epoch
savb(19-21)= coords(4-6,1)
savb(22)= sitf(1)
savb(23-25)= coords(1-3,1)
savb(28-34)= occultation star data
savb(28-39) are used for radio observations
savb(28)= doppler counting interval
savb(28)= biased doppler or ddr counting interval
savb(29)= reference frequency for site1
savb(30)= reference frequency for site2
savb(31)= received frequency at site1
savb(32)= received frequency at site2
savb(33)= counted-cycle vlbi multiplication factor
savb(34)= ddr output bias freq (=xfactr*syn.freq./16)
savb(35)= synthesizer offset  between site1 and site2
savb(36)= half the modulo number for ranging
savb(37)= raw modded range datum
savb(38)= received freq. for second object at site1
savb(39)= received freq. for second object at site2
savb(40)= double precision 'seconds' part of observation epoch
savb(41-46)= meteorological data - should be set to -1 if unknown
defaults are 273.15, 1000, and 0.0
savb(41)= surface temperature in deg k. at site1
savb(42)= surface pressure in millibars at site1
savb(43)= surface relative humidity in percent/100 at site1
savb(44)= surface temperature in deg k. at site2
savb(45)= surface pressure in millibars at site2
savb(46)= surface relative humidity in percent/100 at site2
savb(47)= predicted range residual on prdict tape
savb(48)= receive time offset between sites
savb(48)= height of spacecraft from planet center in km
savb(49-51)= receiving station to spacecraft line of sight
vector in planet rotating frame
savb(52-55)= zenith angles at 1st & 2nd sites of 1st & 2nd
objects
savb(56)= reference epoch for s/c state vector (sec past J2000)
savb(57-62)= s/c state vector in km, km/s relative to system c-o-m

resltb(1,j) = time delay for radar observation (seconds)
right ascension for optical observation (sec.of time)
time that first limb of planet cuts first limb of sun
for transit observation (first part) (seconds)
resltb(2,j) = doppler shift for radar observation (cycles/sec)
declination for optical observatoon (sec.of arc)
time that second limb of planet cuts first limb of sun
for transit observation (first part) (seconds)
resltb(3,j) = time that first limb of planet cuts second limb of sun
for transit observation (second part) (seconds)
resltb(4,j) = time that second limb of planet cuts second limb of sun
for transit observation (second part) (seconds)

niobc,niobs,niabs1  indicate status of data sets  iiobc,
iiobs, iiabs1
-1  not to be read
0  ready to be read
1  already read
if  iiobc, iiobs, or iiabs1  are initially zero,  data set
is not read in any case.

dvx is assumed not needed here, so  not fully dimensioned
if correlated partials should ever be needed, then
dvx would be expanded and must be correctly read
at label=1030

WARN1 tracks state of each series:
'0'=>initial or in midst of real data,
'1'=>first observation,
'+'=>subsequent observation, but previous data were all suppressed

set ncode   for nonzero values of:
1         erobs1
2         erobs1 erobs2
3                erobs2

not dummy mode  iiobs and/or iiabs1 being processed
mtape=0, niabs1=1, niobs=1  compare iiobs,iiabs1
niobs=-1 store iiabs1
mtape=0, niabs1=-1, niobs=1  store iiobs
niobs=-1  return
mtape=1, niobs=1  store iiobs        niobs=-1  return
mtape=2, niabs1=1 store iiabs1      niabs1=-1  return
maybe check mtape = 0,1,2
*  start=3000

*  start=8000
completion of modes being processed by obsred
set ncode=0  so that radar or optic or transit will return
to compar

*  start=7000
ntape not 1    return
ntape=1  niobc=1  iiobcn is read     niobc=-1  return
compare iiobcn with date in /obscrd/