diff --git a/ale/formatters/usgscsm_formatter.py b/ale/formatters/usgscsm_formatter.py
index 0220fa80e7a3967f5149e884520aa8c438b93dad..d395594beefdf0d8bc5d511001a85fc2c7973577 100644
--- a/ale/formatters/usgscsm_formatter.py
+++ b/ale/formatters/usgscsm_formatter.py
@@ -44,16 +44,16 @@ def to_usgscsm(driver):
         'unit' : 'm'
     }
     
+    sun_positions, sun_velocities, _ = driver.sun_position
+    isd_data['sun_position'] = {
+        'positions' : sun_positions,
+        'velocities' : sun_velocities,
+        'unit' : 'm'
+    }
+
     # shared isd keywords for Framer and Linescanner
     if isinstance(driver, LineScanner) or isinstance(driver, Framer):
         # exterior orientation for just Framer and LineScanner
-        sun_positions, sun_velocities, _ = driver.sun_position
-        isd_data['sun_position'] = {
-            'positions' : sun_positions,
-            'velocities' : sun_velocities,
-            'unit' : 'm'
-        }
-
         frame_chain = driver.frame_chain
         sensor_to_target = frame_chain.compute_rotation(driver.sensor_frame_id, driver.target_frame_id)
         quaternions = sensor_to_target.quats
@@ -124,6 +124,8 @@ def to_usgscsm(driver):
         else:
             isd_data['dt_ephemeris'] = 0
 
+        isd_data['t0_ephemeris'] = interp_times[0]
+
     # line scan sensor model specifics
     if isinstance(driver, LineScanner):
         isd_data['name_model'] = 'USGS_ASTRO_LINE_SCANNER_SENSOR_MODEL'
@@ -153,7 +155,7 @@ def to_usgscsm(driver):
 
     # radar sensor model specifics
     if isinstance(driver, Radar):
-        isd_data['name_model'] = 'USGS_ASTRO_SAR_MODEL'
+        isd_data['name_model'] = 'USGS_ASTRO_SAR_SENSOR_MODEL'
         isd_data['starting_ephemeris_time'] = driver.ephemeris_start_time
         isd_data['ending_ephemeris_time'] = driver.ephemeris_stop_time
         isd_data['wavelength'] = driver.wavelength
diff --git a/tests/pytests/data/isds/lrominirf_isd.json b/tests/pytests/data/isds/lrominirf_isd.json
index d726a7e0fcf4df9274b000d1abcde06e6f30762b..15d42dc2332ce0346cd2270455ef14c3a0ffc72f 100644
--- a/tests/pytests/data/isds/lrominirf_isd.json
+++ b/tests/pytests/data/isds/lrominirf_isd.json
@@ -10105,7 +10105,25 @@
     ],
     "unit": "m"
   },
-  "name_model": "USGS_ASTRO_SAR_MODEL",
+ "sun_position": {
+    "positions": [
+      [
+        106362878979.21156,
+        106752639404.5255,
+        3800122792.5012856
+      ]
+    ],
+    "velocities": [
+      [
+        263427.2731009642,
+        -260832.3680061591,
+        -207.62866458328944
+      ]
+    ],
+    "unit": "m"
+  },
+  "name_model": "USGS_ASTRO_SAR_SENSOR_MODEL",
+  "t0_ephemeris": 325441417.4304223,
   "starting_ephemeris_time": 325441417.4304223,
   "ending_ephemeris_time": 325441721.22304827,
   "wavelength": 0.12596322416750805,