Add some standard sphere sizes from EK500 manual

src/echosms/resources/target definitions.toml

@@ -379,6 +379,20 @@ target_transverse_c = "WC_transverse_sound_speed"
 source = "https://doi.org/10.17895/ices.pub.5494"
 benchmark_model = "es"
 
+[[target]]
+name = "Cu10.3 calibration sphere"
+shape = "sphere"
+boundary_type = "elastic"
+description = "A 10.3 mm diameter copper sphere"
+a = 0.00515 # radius
+medium_rho = "medium_density"
+medium_c = "medium_sound_speed"
+target_rho = "Cu_density"
+target_longitudinal_c = "Cu_longitudinal_sound_speed"
+target_transverse_c = "Cu_transverse_sound_speed"
+source = "https://doi.org/10.17895/ices.pub.5494"
+benchmark_model = "es"
+
 [[target]]
 name = "Cu13.7 calibration sphere"
 shape = "sphere"
@@ -421,6 +435,20 @@ target_transverse_c = "Cu_transverse_sound_speed"
 source = "https://doi.org/10.17895/ices.pub.5494"
 benchmark_model = "es"
 
+[[target]]
+name = "Cu32.1 calibration sphere"
+shape = "sphere"
+boundary_type = "elastic"
+description = "A 32.1 mm diameter copper sphere"
+a = 0.01605 # radius
+medium_rho = "medium_density"
+medium_c = "medium_sound_speed"
+target_rho = "Cu_density"
+target_longitudinal_c = "Cu_longitudinal_sound_speed"
+target_transverse_c = "Cu_transverse_sound_speed"
+source = "https://doi.org/10.17895/ices.pub.5494"
+benchmark_model = "es"
+
 [[target]]
 name = "Cu42 calibration sphere"
 shape = "sphere"