'Sat_ID' showed misleading data for singleton observations. It couldn…

…'t compute observed motion in such cases, but emitted zero motions instead. Also, it showed no computed motion, even though motion can and should be computed and displayed in such cases. These problems are now fixed.

sat_id.cpp

@@ -324,6 +324,23 @@ static bool offset_matches_obs( const offset_t *offset, const OBSERVATION *obs)
       return( false);
 }
 
+static int set_observer_location( OBSERVATION *obs)
+{
+   char station_data[100];
+   const int rval = get_station_code_data( station_data, obs->text + 77);
+
+   if( !rval)
+       {
+       mpc_code_t code_data;
+
+       get_mpc_code_info( &code_data, station_data);
+       observer_cartesian_coords( obs->jd, code_data.lon,
+             code_data.rho_cos_phi, code_data.rho_sin_phi, obs->observer_loc);
+       j2000_to_epoch_of_date( obs->jd, &obs->ra, &obs->dec);
+       }
+    return( rval);
+}
+
 /* Loads up MPC-formatted 80-column observations from a file.  Makes
 a pass to find out how many observations there are,  allocates space
 for them,  then reads them again to actually load the observations. */
@@ -347,8 +364,6 @@ static OBSERVATION *get_observations_from_file( FILE *ifile, size_t *n_found,
                    && obs.jd < t_high
                    && (!_target_desig || strstr( buff, _target_desig)))
          {
-         char station_data[100];
-
          if( buff[14] == 's' || buff[14] == 'v')
             {                 /* satellite obs or roving observer */
             offset_t toff;
@@ -391,20 +406,14 @@ static OBSERVATION *get_observations_from_file( FILE *ifile, size_t *n_found,
             offsets = (offset_t *)realloc( offsets, n_offsets * sizeof( offset_t));
             offsets[n_offsets - 1] = toff;
             }
-         else if( !get_station_code_data( station_data, obs.text + 77))
+         else if( !set_observer_location( &obs))
             {
-            mpc_code_t code_data;
-
-            get_mpc_code_info( &code_data, station_data);
-            observer_cartesian_coords( obs.jd, code_data.lon,
-                  code_data.rho_cos_phi, code_data.rho_sin_phi, obs.observer_loc);
             if( count == n_allocated)
                {
                n_allocated += 10 + n_allocated / 2;
                rval = (OBSERVATION *)realloc( rval,
-                                    (n_allocated + 1) * sizeof( OBSERVATION));
+                               (n_allocated + 1) * sizeof( OBSERVATION));
                }
-            j2000_to_epoch_of_date( obs.jd, &obs.ra, &obs.dec);
             rval[count] = obs;
             count++;
             }
@@ -996,12 +1005,23 @@ static int add_tle_to_obs( object_t *objects, const size_t n_objects,
                        && radius < max_expected_error
                        && i == obj_ptr->n_matches)
                   {
-                  const double dt = optr2->jd - optr1->jd;
+                  double dt = optr2->jd - optr1->jd;
+                  const double min_dt = 1e-6;   /* 0.0864 seconds */
                   double motion_diff, ra2, dec2;
                   double temp_array[8];
 
                   assert( dt >= 0.);
-                  compute_artsat_ra_dec( &ra2, &dec2, &dist_to_satellite,
+                  if( !dt)
+                     {
+                     OBSERVATION temp_obs = *optr2;
+
+                     temp_obs.jd += min_dt;
+                     set_observer_location( &temp_obs);
+                     compute_artsat_ra_dec( &ra2, &dec2, &dist_to_satellite,
+                              &temp_obs, &tle, sat_params);
+                     }
+                  else
+                     compute_artsat_ra_dec( &ra2, &dec2, &dist_to_satellite,
                               optr2, &tle, sat_params);
                   temp_array[0] = ra;     /* starting point (computed) */
                   temp_array[1] = dec;
@@ -1065,24 +1085,28 @@ static int add_tle_to_obs( object_t *objects, const size_t n_objects,
                      strlcpy_error( obj_ptr->matches[i].text, obuff + 26);
 //                   snprintf_append( obuff, sizeof( obuff), " motion %f", motion_diff);
                      strlcat_error( obuff, "\n");
+                     if( !dt)
+                        strlcat_error( obuff,
+                              "             no observed motion (single obs) ");
+                     else
+                        snprintf_append( obuff, sizeof( obuff),
+                              "             motion %7.4f\"/sec at PA %5.1f;",
+                              motion_rate, motion_pa);
                      snprintf_append( obuff, sizeof( obuff),
-                        "             motion %7.4f\"/sec at PA %5.1f; dist=%8.1f km; offset=%7.4f deg\n",
-                            motion_rate, motion_pa,
-                            dist_to_satellite, radius);
+                                   " dist=%8.1f km; offset=%7.4f deg\n",
+                                   dist_to_satellite, radius);
                               /* "Speed" is displayed in arcminutes/second,
                                   or in degrees/minute */
                      printf( "%s\n", optr1->text);
                      printf( "%s", obuff);
+                     motion_rate = angular_sep( ra - ra2, dec, dec2, &motion_pa);
+                     motion_rate *= arcminutes_per_radian;
                      if( dt)
-                        {
-                        motion_rate = angular_sep( ra - ra2, dec, dec2, &motion_pa);
-                        motion_rate *= arcminutes_per_radian;
-                        if( dt)
-                           motion_rate /= dt * minutes_per_day;
-                        printf( "             motion %7.4f\"/sec at PA %5.1f (computed)\n",
+                        motion_rate /= dt * minutes_per_day;
+                     else
+                        motion_rate /= min_dt * minutes_per_day;
+                     printf( "             motion %7.4f\"/sec at PA %5.1f (computed)\n",
                             motion_rate, motion_pa);
-                        }
-//                   printf( "             mismatch %5.2f\"\n", motion_diff);
                      printf( "\n");
                      }
                   }