diff --git a/doc/OnlineDocs/source/reference/file_formats/rts-gmlc/simulation_objects.rst b/doc/OnlineDocs/source/reference/file_formats/rts-gmlc/simulation_objects.rst
index 6eba43de..e62e4658 100644
--- a/doc/OnlineDocs/source/reference/file_formats/rts-gmlc/simulation_objects.rst
+++ b/doc/OnlineDocs/source/reference/file_formats/rts-gmlc/simulation_objects.rst
@@ -36,37 +36,6 @@ The following values of :col:`Simulation_Parameter` are supported:
        files
      - The number of seconds between values in *REAL_TIME* timeseries data
        files
-   * - *Date_From*
-     - Yes
-     - The date and time of the first value in each timeseries data file.
-       Most reasonable formats are accepted.
-     - The date and time of the first value in each DAY_AHEAD timeseries data
-       file
-     - The date and time of the first value in each REAL_TIME timeseries data
-       file
-   * - *Date_To*
-     - Yes
-     - The latest date and time for which we have enough data in timeseries
-       files to formulate a RUC or SCED. Most reasonable formats are
-       accepted. See `Date_To Details`_ below.
-     - The latest date and time for which we have enough data in DAY_AHEAD
-       timeseries data files to formulate a RUC
-     - The latest date and time for which we have enough data in REAL_TIME
-       timeseries data files to formulate a SCED
-   * - *Look_Ahead_Periods_Per_Step*
-     - Yes
-     - The default number of look-ahead periods to use in RUC or SCED formulations
-     - The default number of look-ahead periods to use in RUC formulations
-     - The default number of look-ahead periods to use in SCED formulations
-   * - *Look_Ahead_Resolution*
-     - Yes
-     - The default number of seconds between each look-ahead period used in
-       RUC or SCED formulations. See `Look_Ahead_Resolution Details`_ below.
-     - The default number of seconds between each look-ahead period in RUC
-       formulations
-     - The default number of seconds between each look-ahead period in SCED
-       formulations
-       formulations
    * - *Reserve_Products*
      - No
      - Which reserve products to enforce for RUC plans or SCED operations.
@@ -75,32 +44,6 @@ The following values of :col:`Simulation_Parameter` are supported:
      - Which reserve products to enforce for SCED operations
 
 
-Date_To Details
-~~~~~~~~~~~~~~~
-
-The value of *Date_To* identifies the latest time for which there is
-enough data to formulate or RUC (for :col:`DAY_AHEAD`) or SCED (for
-:col:`REAL_TIME`), including look-ahead periods. This is not the date
-and time of the final value in timeseries data files. Instead, the
-*Date_To* is *Look_Ahead_Periods_Per_Step \* Look_Ahead_Resolution*
-before the date and time of the final value in the timeseries data files.
-
-For example, consider a data set with 24 look-ahead periods with a
-look-ahead resolution of 1 hour. If the final value in a timeseries is
-for April 10\ :sup:`th` at midnight, then *Date_To* is April 9\ :sup:`th`
-at midnight, because that is the latest time for which we have enough
-data to satisfy the 24 hour look-ahead requirement.
-
-Look_Ahead_Resolution Details
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-The *Look_Ahead_Resolution* parameter is used to determine the date and time of the
-final value in timeseries data files, as described in `Date_To Details`_. Despite its
-name, it is not used to specify the look-ahead resolution used during simulation. The
-actual look-ahead resolution used during simulation is determined by configuration parameters
-passed to Prescient. Prescient will interpolate the available data as necessary to
-honor the look-ahead resolution specified in its configuration parameters.
-
 Reserve_Products Details
 ~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/prescient/data/providers/gmlc_data_provider.py b/prescient/data/providers/gmlc_data_provider.py
index e8c7e65a..c2854f51 100644
--- a/prescient/data/providers/gmlc_data_provider.py
+++ b/prescient/data/providers/gmlc_data_provider.py
@@ -28,10 +28,21 @@ class GmlcDataProvider(DataProvider):
     '''
 
     def __init__(self, options:Options):
-                                            # midnight start
+        # See how much extra time to parse for lookahead horizon
+        sced_extra_minutes = options.sced_horizon * options.sced_frequency_minutes
+        ruc_extra_minutes = (options.ruc_horizon - options.ruc_every_hours)*60
+        extra_minutes = max(sced_extra_minutes, ruc_extra_minutes)
+
+        # Move minutes to days as needed
+        days=options.num_days
+        while extra_minutes >= 24*60:
+            days += 1
+            extra_minutes -= 24*60
+
+        # Start at midnight of start date
         self._start_time = datetime.combine(options.start_date, datetime.min.time())
-        self._end_time = self._start_time + timedelta(days=options.num_days)
-        self._cache = parser.parse_to_cache(options.data_path, self._start_time, self._end_time)
+        self._end_time = self._start_time + timedelta(days=days, minutes=extra_minutes)
+        self._cache = parser.parse_to_cache(options.data_path, self._start_time, self._end_time, honor_lookahead=False)
 
     def negotiate_data_frequency(self, desired_frequency_minutes:int):
         ''' Get the number of minutes between each timestep of actuals data this provider will supply,
diff --git a/setup.py b/setup.py
index b0789c2c..22f9d7c1 100755
--- a/setup.py
+++ b/setup.py
@@ -46,6 +46,6 @@
                     'prescient.simulator.tests':['regression_tests_data/**/*'],
                    },
       install_requires=['numpy','matplotlib','pandas','scipy','pyomo>=6.1.2',
-                        'python-dateutil','networkx','jupyter', 'gridx-egret==0.5.5',
+                        'python-dateutil','networkx','jupyter', 'gridx-egret==0.5.6.dev0',
                        ],
      )