diff --git a/docs/source/prop.rst b/docs/source/prop.rst
index d53c19a4..61655aa0 100644
--- a/docs/source/prop.rst
+++ b/docs/source/prop.rst
@@ -9,7 +9,7 @@ The force model includes the following effects:
 #. J\ :sub:`2` zonal harmonic effects from the Sun and the Earth
 #. A\ :sub:`1`, A\ :sub:`2`, A\ :sub:`3` nongravitational  acceleration model [#]_
 
-In addition to any integrated bodies defined by the user, the default force model includes effects from the Sun, the planets, the Moon, Pluto, and the Big 16 main-belt asteroids. The states of these bodies are read in from either the JPL DE431 or DE441 ephemerides, based on the user's choice. The propagator can also interpolate any of the integrated bodies' states to any time within the integration (or within a margin around the integration time bounds). This interpolation is done via interpolation polynomials based on the Newton divided difference method.
+In addition to any integrated bodies defined by the user, the default force model includes effects from the Sun, the planets, the Moon, Pluto, and the Big 16 main-belt asteroids. The states of these bodies are read in from either the JPL DE431 or DE441 ephemerides, based on the user's choice. The propagator can also interpolate any of the integrated bodies' states to any time within the integration (or within a margin around the integration time bounds). This interpolation is done directly via polynomial coefficients computed by IAS15 during propagation.
 
 The propagator module also has the ability to calculate apparent states of any integrated body. This is done through two methods. The first is the simpler of the two, and uses a simple approximation of the light-time between an observer and the integrated body. The second method is more accurate, and uses an iterative method to calculate the light-time between an observer and the integrated body. The second method is slightly more computationally expensive since it requires a few extra interpolations.
 
diff --git a/docs/source/start.rst b/docs/source/start.rst
index 0e3950ab..e36b9c6a 100644
--- a/docs/source/start.rst
+++ b/docs/source/start.rst
@@ -60,8 +60,9 @@ You will need to have CMake installed on your system to build the C++ library. O
 
 Keep in mind the C++ library only contains support for propagating orbits and calculating observables. If you want to use the orbit fitting functionality, you will need to install the full Python library.
 
+-----
 Usage
-=====
+-----
 Once the GRSS library has been installed, it can be imported into a Python script using the following command:
 
 .. code-block:: python
diff --git a/src/pck.cpp b/src/pck.cpp
index 377709dd..28fd5d1e 100644
--- a/src/pck.cpp
+++ b/src/pck.cpp
@@ -189,7 +189,7 @@ PckInfo* pck_init(const std::string &path) {
 
 /**
  * @param[in] bpc PckInfo structure.
- * @param[in] epoch Epoch to compute the state at (MJD ET).
+ * @param[in] epoch Epoch to compute the state at (MJD TDB).
  * @param[in] spiceId SPICE ID of the frame.
  * @param[out] rotMat Rotation matrix
  * @param[out] rotMatDot Derivative of the rotation matrix
@@ -264,7 +264,7 @@ void pck_calc(PckInfo *bpc, real epoch, int spiceId, real *rotMat,
 }
 
 /**
- * @param[in] t0_mjd Epoch to compute the rotation matrix at (MJD ET).
+ * @param[in] t0_mjd Epoch to compute the rotation matrix at (MJD TDB).
  * @param[in] iauFrame IAU frame name.
  * @param[out] euler Real array of 6 elements containing the 313 Euler angles and their derivatives.
  */
@@ -700,7 +700,7 @@ void euler313_to_rotMat(const real euler[6], real *rotMat, real *rotMatDot){
 /**
  * @param[in] from Frame to rotate from.
  * @param[in] to Frame to rotate to.
- * @param[in] t0_mjd t0_mjd Epoch to compute the rotation matrix at (MJD ET).
+ * @param[in] t0_mjd t0_mjd Epoch to compute the rotation matrix at (MJD TDB).
  * @param[in] ephem PckEphemeris structure.
  * @param[out] xformMat Rotation matrix from 'from' to 'to'.
  */
diff --git a/src/spk.cpp b/src/spk.cpp
index 3ae50639..5d4307ee 100644
--- a/src/spk.cpp
+++ b/src/spk.cpp
@@ -186,7 +186,7 @@ SpkInfo* spk_init(const std::string &path) {
 
 /**
  * @param[in] bsp SpkInfo structure.
- * @param[in] epoch Epoch to compute the state at (MJD ET).
+ * @param[in] epoch Epoch to compute the state at (MJD TDB).
  * @param[in] spiceId SPICE ID of the body.
  * @param[out] state State+acceleration of the body at the requested epoch [AU, AU/day, AU/day^2].
  */
@@ -248,7 +248,7 @@ void spk_calc(SpkInfo *bsp, double epoch, int spiceId, double *state) {
 
 /**
  * @param[in] spiceId SPICE ID of the body.
- * @param[in] t0_mjd Epoch to compute the state at (MJD ET).
+ * @param[in] t0_mjd Epoch to compute the state at (MJD TDB).
  * @param[in] ephem Ephemeris data from the PropSimulation.
  * @param[out] state State+acceleration of the body at the requested epoch [AU, AU/day, AU/day^2].
  * @param[in] writeCache If true, the state will be written to the cache.