From a96138921298ae900039e0cf536651efe0118d9d Mon Sep 17 00:00:00 2001
From: Luisa <luisa.coakley@lasp.colorado.edu>
Date: Wed, 17 Dec 2025 12:19:37 -0700
Subject: [PATCH 1/8] use aux packet to get spins

---
 .../tests/ultra/unit/test_ultra_l1b.py        | 16 ++--
 .../ultra/unit/test_ultra_l1b_culling.py      | 26 +++--
 .../ultra/unit/test_ultra_l1b_extended.py     | 28 +++++-
 imap_processing/ultra/l1b/badtimes.py         |  2 +-
 imap_processing/ultra/l1b/de.py               |  5 +-
 imap_processing/ultra/l1b/extendedspin.py     |  2 +-
 imap_processing/ultra/l1b/goodtimes.py        |  2 +-
 .../ultra/l1b/ultra_l1b_culling.py            | 81 +---------------
 .../ultra/l1b/ultra_l1b_extended.py           | 94 ++++++++++++++-----
 imap_processing/ultra/l1c/helio_pset.py       |  4 +
 imap_processing/ultra/l1c/spacecraft_pset.py  |  4 +
 imap_processing/ultra/l1c/ultra_l1c.py        |  8 ++
 .../ultra/l1c/ultra_l1c_pset_bins.py          |  9 +-
 13 files changed, 156 insertions(+), 125 deletions(-)

diff --git a/imap_processing/tests/ultra/unit/test_ultra_l1b.py b/imap_processing/tests/ultra/unit/test_ultra_l1b.py
index fe6e08f59..70f55e576 100644
--- a/imap_processing/tests/ultra/unit/test_ultra_l1b.py
+++ b/imap_processing/tests/ultra/unit/test_ultra_l1b.py
@@ -190,7 +190,7 @@ def test_cdf_de_flags(
 
 @pytest.mark.external_test_data
 def test_ultra_l1b_extendedspin(
-    use_fake_spin_data_for_time, faux_aux_dataset, rates_dataset
+    use_fake_spin_data_for_time, aux_dataset, rates_dataset
 ):
     """Tests that L1b data is created."""
     use_fake_spin_data_for_time(0, 141 * 15)
@@ -205,7 +205,7 @@ def test_ultra_l1b_extendedspin(
             "imap_ultra_l1a_45sensor-params",
         ]
     }
-    data_dict["imap_ultra_l1a_45sensor-aux"] = faux_aux_dataset
+    data_dict["imap_ultra_l1a_45sensor-aux"] = aux_dataset
     data_dict["imap_ultra_l1a_45sensor-rates"] = rates_dataset
 
     ancillary_files = {}
@@ -219,7 +219,7 @@ def test_ultra_l1b_extendedspin(
 
 
 @pytest.mark.external_test_data
-def test_cdf_extendedspin(use_fake_spin_data_for_time, faux_aux_dataset, rates_dataset):
+def test_cdf_extendedspin(use_fake_spin_data_for_time, aux_dataset, rates_dataset):
     use_fake_spin_data_for_time(0, 141 * 15)
     l1b_de_dataset_path = (
         TEST_PATH / "imap_ultra_l1b_45sensor-de_20240207-repoint99999_v999.cdf"
@@ -233,7 +233,7 @@ def test_cdf_extendedspin(use_fake_spin_data_for_time, faux_aux_dataset, rates_d
             "imap_ultra_l1a_45sensor-params",
         ]
     }
-    data_dict["imap_ultra_l1a_45sensor-aux"] = faux_aux_dataset
+    data_dict["imap_ultra_l1a_45sensor-aux"] = aux_dataset
     data_dict["imap_ultra_l1a_45sensor-rates"] = rates_dataset
 
     ancillary_files = {}
@@ -251,7 +251,7 @@ def test_cdf_extendedspin(use_fake_spin_data_for_time, faux_aux_dataset, rates_d
 
 
 @pytest.mark.external_test_data
-def test_cdf_goodtimes(use_fake_spin_data_for_time, faux_aux_dataset, rates_dataset):
+def test_cdf_goodtimes(use_fake_spin_data_for_time, aux_dataset, rates_dataset):
     """Tests that CDF file is created and contains same attributes as xarray."""
     use_fake_spin_data_for_time(0, 141 * 15)
     l1b_de_dataset_path = (
@@ -266,7 +266,7 @@ def test_cdf_goodtimes(use_fake_spin_data_for_time, faux_aux_dataset, rates_data
             "imap_ultra_l1a_45sensor-params",
         ]
     }
-    data_dict["imap_ultra_l1a_45sensor-aux"] = faux_aux_dataset
+    data_dict["imap_ultra_l1a_45sensor-aux"] = aux_dataset
     data_dict["imap_ultra_l1a_45sensor-rates"] = rates_dataset
 
     ancillary_files = {}
@@ -288,7 +288,7 @@ def test_cdf_goodtimes(use_fake_spin_data_for_time, faux_aux_dataset, rates_data
 
 
 @pytest.mark.external_test_data
-def test_cdf_badtimes(use_fake_spin_data_for_time, faux_aux_dataset, rates_dataset):
+def test_cdf_badtimes(use_fake_spin_data_for_time, aux_dataset, rates_dataset):
     """Tests that CDF file is created and contains same attributes as xarray."""
     use_fake_spin_data_for_time(0, 141 * 15)
     l1b_de_dataset_path = (
@@ -303,7 +303,7 @@ def test_cdf_badtimes(use_fake_spin_data_for_time, faux_aux_dataset, rates_datas
             "imap_ultra_l1a_45sensor-params",
         ]
     }
-    data_dict["imap_ultra_l1a_45sensor-aux"] = faux_aux_dataset
+    data_dict["imap_ultra_l1a_45sensor-aux"] = aux_dataset
     data_dict["imap_ultra_l1a_45sensor-rates"] = rates_dataset
 
     ancillary_files = {}
diff --git a/imap_processing/tests/ultra/unit/test_ultra_l1b_culling.py b/imap_processing/tests/ultra/unit/test_ultra_l1b_culling.py
index ff80abaec..7daaa0279 100644
--- a/imap_processing/tests/ultra/unit/test_ultra_l1b_culling.py
+++ b/imap_processing/tests/ultra/unit/test_ultra_l1b_culling.py
@@ -3,6 +3,7 @@
 import numpy as np
 import pandas as pd
 import pytest
+import xarray as xr
 
 from imap_processing import imap_module_directory
 from imap_processing.quality_flags import (
@@ -170,21 +171,34 @@ def test_compare_aux_univ_spin_table(use_fake_spin_data_for_time, faux_aux_datas
     assert np.all(result == expected)
 
 
-def test_get_duration(rates_l1_test_path, use_fake_spin_data_for_time):
+def test_get_duration(rates_l1_test_path, use_fake_spin_data_for_time, aux_test_path):
     """Tests get_duration function."""
     use_fake_spin_data_for_time(start_met=0, end_met=141 * 15)
-
     df = pd.read_csv(rates_l1_test_path)
 
+    # Should be evenly spaced spins of 15 seconds each except the first one has 14.
+    num_spins = 15
+    spin_start_times = np.concatenate([[0], np.arange(14, 222, num_spins)])
+    spin_numbers = np.arange(127, 142)
+    num_spins = len(spin_numbers)
+
+    aux_ds = xr.Dataset(
+        data_vars={
+            "timespinstart": ("epoch", spin_start_times),
+            "duration": ("epoch", np.full(num_spins, 15)),
+            "spinnumber": ("epoch", spin_numbers),
+        },
+        coords={"epoch": ("epoch", np.arange(num_spins))},
+    )
+
     met = df["TimeTag"] - df["TimeTag"].values[0]
     spin = df["Spin"]
-    spin_number, duration = get_spin_and_duration(met, spin)
-
+    spin_number, duration = get_spin_and_duration(aux_ds, met)
     assert np.array_equal(spin, spin_number)
     assert np.all(duration == 15)
 
 
-def test_get_pulses(rates_l1_test_path, use_fake_spin_data_for_time):
+def test_get_pulses(rates_l1_test_path, use_fake_spin_data_for_time, aux_dataset):
     """Tests get_pulses_per_spin function."""
     df = pd.read_csv(rates_l1_test_path)
 
@@ -214,7 +228,7 @@ def test_get_pulses(rates_l1_test_path, use_fake_spin_data_for_time):
         "spin": df["Spin"],
     }
 
-    pulses = get_pulses_per_spin(pulse_dict)
+    pulses = get_pulses_per_spin(aux_dataset, pulse_dict)
     unique_spins = np.unique(pulse_dict["spin"])
 
     start_pulses_total = pulse_dict["start_rf"] + pulse_dict["start_lf"]
diff --git a/imap_processing/tests/ultra/unit/test_ultra_l1b_extended.py b/imap_processing/tests/ultra/unit/test_ultra_l1b_extended.py
index 08a5a8c6a..5cc1fdc79 100644
--- a/imap_processing/tests/ultra/unit/test_ultra_l1b_extended.py
+++ b/imap_processing/tests/ultra/unit/test_ultra_l1b_extended.py
@@ -31,6 +31,7 @@
     get_path_length,
     get_ph_tof_and_back_positions,
     get_phi_theta,
+    get_spin_and_duration,
     get_ssd_back_position_and_tof_offset,
     get_ssd_tof,
     interpolate_fwhm,
@@ -521,7 +522,7 @@ def test_get_eventtimes(test_fixture, aux_dataset):
     """Tests get_eventtimes function."""
     df_filt, _, _, de_dataset = test_fixture
 
-    event_times, spin_start_times, spin_numbers = get_event_times(
+    event_times, spin_start_times = get_event_times(
         aux_dataset,
         de_dataset["phase_angle"].values,
         de_dataset["shcoarse"].values,
@@ -529,10 +530,7 @@ def test_get_eventtimes(test_fixture, aux_dataset):
 
     # Check shapes
     assert (
-        event_times.shape
-        == spin_start_times.shape
-        == spin_numbers.shape
-        == de_dataset["phase_angle"].shape
+        event_times.shape == spin_start_times.shape == de_dataset["phase_angle"].shape
     )
 
     t1_start_sec = aux_dataset["timespinstart"].values[0]
@@ -561,6 +559,26 @@ def test_get_eventtimes(test_fixture, aux_dataset):
         assert start_time <= int(event_times[i]) <= end_time
 
 
+@pytest.mark.external_test_data
+def test_get_spin_and_duration(test_fixture, aux_dataset):
+    """Tests get_eventtimes function."""
+    df_filt, _, _, de_dataset = test_fixture
+
+    spin_number, spin_duration = get_spin_and_duration(
+        aux_dataset,
+        de_dataset["shcoarse"].values,
+    )
+
+    # Check shapes
+    assert spin_number.shape == spin_duration.shape == de_dataset["shcoarse"].shape
+
+    t1_spin_number = aux_dataset["spinnumber"].values[0]
+    t1_start_dur = aux_dataset["duration"].values[0]
+    # Check the first event spin number and duration
+    assert spin_number[0] == t1_spin_number
+    assert spin_duration[0] == t1_start_dur
+
+
 @pytest.mark.external_test_data
 def test_get_event_times_out_of_range(test_fixture, aux_dataset):
     """Tests get_event_times with out of range values."""
diff --git a/imap_processing/ultra/l1b/badtimes.py b/imap_processing/ultra/l1b/badtimes.py
index a3f82ef40..c78520a49 100644
--- a/imap_processing/ultra/l1b/badtimes.py
+++ b/imap_processing/ultra/l1b/badtimes.py
@@ -34,7 +34,7 @@ def calculate_badtimes(
     badtimes_dataset : xarray.Dataset
         Dataset containing the extendedspin data that has been culled.
     """
-    n_bins = extendedspin_dataset.dims["energy_bin_geometric_mean"]
+    n_bins = extendedspin_dataset.sizes["energy_bin_geometric_mean"]
     culled_spins = np.setdiff1d(
         extendedspin_dataset["spin_number"].values, goodtimes_spins
     )
diff --git a/imap_processing/ultra/l1b/de.py b/imap_processing/ultra/l1b/de.py
index acc0f65de..d8f6e266b 100644
--- a/imap_processing/ultra/l1b/de.py
+++ b/imap_processing/ultra/l1b/de.py
@@ -37,6 +37,7 @@
     get_path_length,
     get_ph_tof_and_back_positions,
     get_phi_theta,
+    get_spin_and_duration,
     get_ssd_back_position_and_tof_offset,
     get_ssd_tof,
     is_back_tof_valid,
@@ -158,11 +159,13 @@ def calculate_de(
         ancillary_files,
     )
     start_type[valid_indices] = de_dataset["start_type"].data[valid_indices]
-    (event_times, spin_starts, spin_number) = get_event_times(
+    (event_times, spin_starts) = get_event_times(
         aux_dataset,
         de_dataset["phase_angle"].data,
         de_dataset["shcoarse"].data,
     )
+    spin_number, _ = get_spin_and_duration(aux_dataset, de_dataset["shcoarse"].data)
+
     de_dict["spin"] = spin_number
     de_dict["event_times"] = event_times.astype(np.float64)
     # Pulse height
diff --git a/imap_processing/ultra/l1b/extendedspin.py b/imap_processing/ultra/l1b/extendedspin.py
index 93f3faf1c..b930d1107 100644
--- a/imap_processing/ultra/l1b/extendedspin.py
+++ b/imap_processing/ultra/l1b/extendedspin.py
@@ -61,7 +61,7 @@ def calculate_extendedspin(
     inst_qf = flag_imap_instruments(de_dataset["spin"].values)
 
     # Get the number of pulses per spin.
-    pulses = get_pulses_per_spin(rates_dataset)
+    pulses = get_pulses_per_spin(aux_dataset, rates_dataset)
 
     # Track rejected events in each spin based on
     # quality flags in de l1b data.
diff --git a/imap_processing/ultra/l1b/goodtimes.py b/imap_processing/ultra/l1b/goodtimes.py
index 1271d6adb..915c770b5 100644
--- a/imap_processing/ultra/l1b/goodtimes.py
+++ b/imap_processing/ultra/l1b/goodtimes.py
@@ -28,7 +28,7 @@ def calculate_goodtimes(extendedspin_dataset: xr.Dataset, name: str) -> xr.Datas
     goodtimes_dataset : xarray.Dataset
         Dataset containing the extendedspin data that remains after culling.
     """
-    n_bins = extendedspin_dataset.dims["energy_bin_geometric_mean"]
+    n_bins = extendedspin_dataset.sizes["energy_bin_geometric_mean"]
     # If the spin rate was too high or low then the spin should be thrown out.
     # If the rates at any energy level are too high then throw out the entire spin.
     good_mask = (
diff --git a/imap_processing/ultra/l1b/ultra_l1b_culling.py b/imap_processing/ultra/l1b/ultra_l1b_culling.py
index d95af415e..9e429e93c 100644
--- a/imap_processing/ultra/l1b/ultra_l1b_culling.py
+++ b/imap_processing/ultra/l1b/ultra_l1b_culling.py
@@ -22,6 +22,7 @@
     get_scattering_thresholds,
 )
 from imap_processing.ultra.l1b.quality_flag_filters import DE_QUALITY_FLAG_FILTERS
+from imap_processing.ultra.l1b.ultra_l1b_extended import get_spin_and_duration
 from imap_processing.ultra.l1c.l1c_lookup_utils import build_energy_bins
 
 logger = logging.getLogger(__name__)
@@ -339,86 +340,14 @@ def compare_aux_univ_spin_table(
     return mismatch_indices
 
 
-# TODO: Make this a common util since it is being used for the de and rates packets.
-def get_spin_and_duration(met: NDArray, spin: NDArray) -> tuple[NDArray, NDArray]:
-    """
-    Get the spin number and duration.
-
-    Parameters
-    ----------
-    met : NDArray
-        Mission elapsed time.
-    spin : NDArray
-        Spin number 0-255.
-
-    Returns
-    -------
-    assigned_spin_number : NDArray
-        Spin number for packet data product.
-    """
-    # Packet data.
-    # Since the spin number in the direct events packet
-    # is only 8 bits it goes from 0-255.
-    # Within a pointing that means we will always have duplicate spin numbers.
-    # In other words, different spins will be represented by the same spin number.
-    # Just to make certain that we won't accidentally combine
-    # multiple spins we need to sort by time here.
-    sort_idx = np.argsort(met)
-    packet_met_sorted = met[sort_idx]
-    packet_spin_sorted = spin[sort_idx]
-    # Here we are finding the start and end indices of each spin in the sorted array.
-    is_new_spin = np.concatenate(
-        [[True], packet_spin_sorted.values[1:] != packet_spin_sorted.values[:-1]]
-    )
-    spin_start_indices = np.where(is_new_spin)[0]
-    spin_end_indices = np.append(spin_start_indices[1:], len(packet_met_sorted))
-
-    # Universal Spin Table.
-    spin_df = get_spin_data()
-    # Retrieve the met values of the start of the spin.
-    spin_start_mets = spin_df["spin_start_met"].values
-    # Retrieve the corresponding spin numbers.
-    spin_numbers = spin_df["spin_number"].values
-    spin_period_sec = spin_df["spin_period_sec"].values
-    assigned_spin_number_sorted = np.empty(packet_spin_sorted.shape, dtype=np.uint32)
-    assigned_spin_duration_sorted = np.empty(packet_spin_sorted.shape, dtype=np.float32)
-    # These last 8 bits are the same as the spin number in the DE packet.
-    # So this will give us choices of which spins are
-    # available to assign to the packet data.
-    possible_spins = spin_numbers & 0xFF
-
-    # Assign each group based on time.
-    for start, end in zip(spin_start_indices, spin_end_indices, strict=False):
-        # Now that we have the possible spins from the Universal Spin Table,
-        # we match the times of those spins to the nearest times in the DE data.
-        possible_times = spin_start_mets[
-            possible_spins == packet_spin_sorted.values[start]
-        ]
-        # Get nearest time for matching spins.
-        nearest_idx = np.abs(possible_times - packet_met_sorted.values[start]).argmin()
-        nearest_value = possible_times[nearest_idx]
-        assigned_spin_number_sorted[start:end] = spin_numbers[
-            spin_start_mets == nearest_value
-        ]
-        assigned_spin_duration_sorted[start:end] = spin_period_sec[
-            spin_start_mets == nearest_value
-        ]
-
-    # Undo the sort to match original order.
-    assigned_spin_number = np.empty_like(assigned_spin_number_sorted)
-    assigned_spin_number[sort_idx] = assigned_spin_number_sorted
-    assigned_duration = np.empty_like(assigned_spin_duration_sorted)
-    assigned_duration[sort_idx] = assigned_spin_duration_sorted
-
-    return assigned_spin_number, assigned_duration
-
-
-def get_pulses_per_spin(rates: xr.Dataset) -> RateResult:
+def get_pulses_per_spin(aux: xr.Dataset, rates: xr.Dataset) -> RateResult:
     """
     Get the total number of pulses per spin.
 
     Parameters
     ----------
+    aux : xr.Dataset
+        Auxiliary dataset.
     rates : xr.Dataset
         Rates dataset.
 
@@ -439,7 +368,7 @@ def get_pulses_per_spin(rates: xr.Dataset) -> RateResult:
     coin_pulses : NDArray
         Total coincidence pulses.
     """
-    spin_number, _duration = get_spin_and_duration(rates["shcoarse"], rates["spin"])
+    spin_number, _ = get_spin_and_duration(aux, rates["shcoarse"].values)
 
     # Top coin pulses
     top_coin_pulses = np.stack(
diff --git a/imap_processing/ultra/l1b/ultra_l1b_extended.py b/imap_processing/ultra/l1b/ultra_l1b_extended.py
index 4618d7cf8..3d61de725 100644
--- a/imap_processing/ultra/l1b/ultra_l1b_extended.py
+++ b/imap_processing/ultra/l1b/ultra_l1b_extended.py
@@ -917,40 +917,24 @@ def get_phi_theta(
     return np.degrees(phi), np.degrees(theta)
 
 
-def get_event_times(
-    aux_dataset: xr.Dataset, phase_angle: NDArray, de_event_met: NDArray
-) -> tuple[NDArray, NDArray, NDArray]:
+def get_spin_start_indices(aux_dataset: xr.Dataset, de_event_met: NDArray) -> NDArray:
     """
-    Get the event times, spin start times, and spin numbers.
-
-    Use formula from section 3.3.1 of the ULTRA algorithm document.
-    t_e = t_spin_start + (t_start_sub / 1000) +
-        (t_spin_duration * theta_event) / (1000 * 720)
+    Get the spin start indices in the aux dataset for each event.
 
     Parameters
     ----------
     aux_dataset : numpy.ndarray
         Auxiliary dataset containing spin information.
-    phase_angle : numpy.ndarray
-        Phase angle.
     de_event_met : numpy.ndarray
         Direct event MET.
 
     Returns
     -------
-    event_times : numpy.ndarray
-        Event times in et.
-    spin_start_times: numpy.ndarray
-        Spin start times in et.
-    spin_numbers: numpy.ndarray
-        Spin numbers for each event.
+    start_inds : numpy.ndarray
+        Spin start indices for each event.
     """
     # Get Spin Start Time in seconds
     spin_start_sec = aux_dataset["timespinstart"].values
-    # Get Spin Start Subsecond in milliseconds
-    spin_start_subsec = aux_dataset["timespinstartsub"].values
-    # Get spin duration in milliseconds
-    spin_duration = aux_dataset["duration"].values
 
     # Check that all events fall within the aux dataset time range.
     # The time window spans from the first spin start to the end of the last spin.
@@ -968,9 +952,44 @@ def get_event_times(
     start_inds = np.searchsorted(spin_start_sec, de_event_met, side="right") - 1
     # Clip to valid range of indices
     start_inds = np.clip(start_inds, 0, len(spin_start_sec) - 1)
-    # Get the spin numbers for each event
-    spin_numbers = aux_dataset["spinnumber"].values[start_inds]
 
+    return start_inds
+
+
+def get_event_times(
+    aux_dataset: xr.Dataset, phase_angle: NDArray, de_event_met: NDArray
+) -> tuple[NDArray, NDArray]:
+    """
+    Get the event times, spin start times.
+
+    Use formula from section 3.3.1 of the ULTRA algorithm document.
+    t_e = t_spin_start + (t_start_sub / 1000) +
+        (t_spin_duration * theta_event) / (1000 * 720)
+
+    Parameters
+    ----------
+    aux_dataset : numpy.ndarray
+        Auxiliary dataset containing spin information.
+    phase_angle : numpy.ndarray
+        Phase angle.
+    de_event_met : numpy.ndarray
+        Direct event MET.
+
+    Returns
+    -------
+    event_times : numpy.ndarray
+        Event times in et.
+    spin_start_times: numpy.ndarray
+        Spin start times in et.
+    """
+    # Get Spin Start Time in seconds
+    spin_start_sec = aux_dataset["timespinstart"].values
+    # Get Spin Start Subsecond in milliseconds
+    spin_start_subsec = aux_dataset["timespinstartsub"].values
+    # Get spin duration in milliseconds
+    spin_duration = aux_dataset["duration"].values
+
+    start_inds = get_spin_start_indices(aux_dataset, de_event_met)
     # Get the relevant spin parameters for each event
     evt_spin_starts = spin_start_sec[start_inds]
     evt_spin_start_subs = spin_start_subsec[start_inds]
@@ -986,10 +1005,39 @@ def get_event_times(
     return (
         ttj2000ns_to_et(met_to_ttj2000ns(event_times)),
         ttj2000ns_to_et(met_to_ttj2000ns(spin_start_times)),
-        spin_numbers,
     )
 
 
+def get_spin_and_duration(
+    aux_dataset: xr.Dataset, de_event_met: NDArray
+) -> tuple[NDArray, NDArray]:
+    """
+    Get the spin numbers and durations.
+
+    Parameters
+    ----------
+    aux_dataset : numpy.ndarray
+        Auxiliary dataset containing spin information.
+    de_event_met : numpy.ndarray
+        Direct event MET.
+
+    Returns
+    -------
+    spin_numbers: numpy.ndarray
+        Spin numbers for each event.
+    spin_durations: numpy.ndarray
+        Spin durations for each event.
+    """
+    # Get the spin start indices for each event
+    start_inds = get_spin_start_indices(aux_dataset, de_event_met)
+    # Get the spin numbers for each event
+    spin_numbers = aux_dataset["spinnumber"].values[start_inds]
+    # Get the spin duration for each event
+    spin_durations = aux_dataset["duration"].values[start_inds]
+
+    return spin_numbers, spin_durations
+
+
 def interpolate_fwhm(
     lookup_table: pandas.DataFrame,
     energy: NDArray,
diff --git a/imap_processing/ultra/l1c/helio_pset.py b/imap_processing/ultra/l1c/helio_pset.py
index 228db8f3e..64c0d8862 100644
--- a/imap_processing/ultra/l1c/helio_pset.py
+++ b/imap_processing/ultra/l1c/helio_pset.py
@@ -39,6 +39,7 @@ def calculate_helio_pset(
     de_dataset: xr.Dataset,
     goodtimes_dataset: xr.Dataset,
     rates_dataset: xr.Dataset,
+    aux_dataset: xr.Dataset,,
     name: str,
     ancillary_files: dict,
     instrument_id: int,
@@ -55,6 +56,8 @@ def calculate_helio_pset(
         Dataset containing goodtimes data.
     rates_dataset : xarray.Dataset
         Dataset containing image rates data.
+    aux_dataset : xarray.Dataset
+        Dataset containing auxiliary data.
     name : str
         Name of the dataset.
     ancillary_files : dict
@@ -176,6 +179,7 @@ def calculate_helio_pset(
     # Calculate background rates
     background_rates = get_spacecraft_background_rates(
         rates_dataset,
+        aux_dataset,
         sensor_id,
         ancillary_files,
         intervals,
diff --git a/imap_processing/ultra/l1c/spacecraft_pset.py b/imap_processing/ultra/l1c/spacecraft_pset.py
index 9cf2aaae2..40a2e401c 100644
--- a/imap_processing/ultra/l1c/spacecraft_pset.py
+++ b/imap_processing/ultra/l1c/spacecraft_pset.py
@@ -37,6 +37,7 @@ def calculate_spacecraft_pset(
     de_dataset: xr.Dataset,
     goodtimes_dataset: xr.Dataset,
     rates_dataset: xr.Dataset,
+    aux_dataset: xr.Dataset,
     name: str,
     ancillary_files: dict,
     instrument_id: int,
@@ -53,6 +54,8 @@ def calculate_spacecraft_pset(
         Dataset containing goodtimes data.
     rates_dataset : xarray.Dataset
         Dataset containing image rates data.
+    aux_dataset : xarray.Dataset
+        Dataset containing auxiliary data.
     name : str
         Name of the dataset.
     ancillary_files : dict
@@ -163,6 +166,7 @@ def calculate_spacecraft_pset(
     # Calculate background rates
     background_rates = get_spacecraft_background_rates(
         rates_dataset,
+        aux_dataset,
         sensor_id,
         ancillary_files,
         intervals,
diff --git a/imap_processing/ultra/l1c/ultra_l1c.py b/imap_processing/ultra/l1c/ultra_l1c.py
index 75981180f..1456d1d66 100644
--- a/imap_processing/ultra/l1c/ultra_l1c.py
+++ b/imap_processing/ultra/l1c/ultra_l1c.py
@@ -35,12 +35,14 @@ def ultra_l1c(
             f"imap_ultra_l1b_{instrument_id}sensor-goodtimes" in data_dict
             and f"imap_ultra_l1b_{instrument_id}sensor-de" in data_dict
             and f"imap_ultra_l1a_{instrument_id}sensor-rates" in data_dict
+            and f"imap_ultra_l1a_{instrument_id}sensor-aux" in data_dict
             and create_helio_pset
         ):
             helio_pset = calculate_helio_pset(
                 data_dict[f"imap_ultra_l1b_{instrument_id}sensor-de"],
                 data_dict[f"imap_ultra_l1b_{instrument_id}sensor-goodtimes"],
                 data_dict[f"imap_ultra_l1a_{instrument_id}sensor-rates"],
+                data_dict[f"imap_ultra_l1a_{instrument_id}sensor-aux"],
                 f"imap_ultra_l1c_{instrument_id}sensor-heliopset",
                 ancillary_files,
                 instrument_id,
@@ -51,11 +53,15 @@ def ultra_l1c(
             f"imap_ultra_l1b_{instrument_id}sensor-goodtimes" in data_dict
             and f"imap_ultra_l1b_{instrument_id}sensor-de" in data_dict
             and f"imap_ultra_l1a_{instrument_id}sensor-rates" in data_dict
+            and f"imap_ultra_l1a_{instrument_id}sensor-aux" in data_dict
+            and f"imap_ultra_l1a_{instrument_id}sensor-params" in data_dict
         ):
             spacecraft_pset = calculate_spacecraft_pset(
                 data_dict[f"imap_ultra_l1b_{instrument_id}sensor-de"],
                 data_dict[f"imap_ultra_l1b_{instrument_id}sensor-goodtimes"],
                 data_dict[f"imap_ultra_l1a_{instrument_id}sensor-rates"],
+                data_dict[f"imap_ultra_l1a_{instrument_id}sensor-aux"],
+                data_dict[f"imap_ultra_l1a_{instrument_id}sensor-params"],
                 f"imap_ultra_l1c_{instrument_id}sensor-spacecraftpset",
                 ancillary_files,
                 instrument_id,
@@ -66,6 +72,8 @@ def ultra_l1c(
                 data_dict[f"imap_ultra_l1b_{instrument_id}sensor-de"],
                 data_dict[f"imap_ultra_l1b_{instrument_id}sensor-goodtimes"],
                 data_dict[f"imap_ultra_l1a_{instrument_id}sensor-rates"],
+                data_dict[f"imap_ultra_l1a_{instrument_id}sensor-aux"],
+                data_dict[f"imap_ultra_l1a_{instrument_id}sensor-params"],
                 f"imap_ultra_l1c_{instrument_id}sensor-spacecraftpset-nonproton",
                 ancillary_files,
                 instrument_id,
diff --git a/imap_processing/ultra/l1c/ultra_l1c_pset_bins.py b/imap_processing/ultra/l1c/ultra_l1c_pset_bins.py
index 44c265499..b46aba032 100644
--- a/imap_processing/ultra/l1c/ultra_l1c_pset_bins.py
+++ b/imap_processing/ultra/l1c/ultra_l1c_pset_bins.py
@@ -23,11 +23,11 @@
 )
 from imap_processing.ultra.l1b.ultra_l1b_culling import (
     get_pulses_per_spin,
-    get_spin_and_duration,
 )
 from imap_processing.ultra.l1b.ultra_l1b_extended import (
     get_efficiency,
     get_efficiency_interpolator,
+    get_spin_and_duration,
 )
 from imap_processing.ultra.l1c.l1c_lookup_utils import (
     build_energy_bins,
@@ -645,6 +645,7 @@ def get_efficiencies_and_geometric_function(
 
 def get_spacecraft_background_rates(
     rates_dataset: xr.Dataset,
+    aux_dataset: xr.Dataset,
     sensor_id: int,
     ancillary_files: dict,
     energy_bin_edges: list[tuple[float, float]],
@@ -658,6 +659,8 @@ def get_spacecraft_background_rates(
     ----------
     rates_dataset : xr.Dataset
         Rates dataset.
+    aux_dataset : xr.Dataset
+        Auxiliary dataset.
     sensor_id : int
         Sensor ID: either 45 or 90.
     ancillary_files : dict[Path]
@@ -680,12 +683,12 @@ def get_spacecraft_background_rates(
     -----
     See Eqn. 3, 8, and 20 in the Algorithm Document for the equation.
     """
-    pulses = get_pulses_per_spin(rates_dataset)
+    pulses = get_pulses_per_spin(aux_dataset, rates_dataset)
     # Pulses for the pointing.
     etof_min = get_image_params("eTOFMin", f"ultra{sensor_id}", ancillary_files)
     etof_max = get_image_params("eTOFMax", f"ultra{sensor_id}", ancillary_files)
     spin_number, _ = get_spin_and_duration(
-        rates_dataset["shcoarse"], rates_dataset["spin"]
+        aux_dataset, rates_dataset["shcoarse"].values
     )
 
     # Get dmin for PH (mm).

From 13607dfaae9d4e20d2963fc4dd3515114bc39c1c Mon Sep 17 00:00:00 2001
From: Luisa <luisa.coakley@lasp.colorado.edu>
Date: Wed, 17 Dec 2025 12:20:54 -0700
Subject: [PATCH 2/8] name unused var'

---
 imap_processing/ultra/l1b/ultra_l1b_culling.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/imap_processing/ultra/l1b/ultra_l1b_culling.py b/imap_processing/ultra/l1b/ultra_l1b_culling.py
index 9e429e93c..518e71a2b 100644
--- a/imap_processing/ultra/l1b/ultra_l1b_culling.py
+++ b/imap_processing/ultra/l1b/ultra_l1b_culling.py
@@ -368,7 +368,7 @@ def get_pulses_per_spin(aux: xr.Dataset, rates: xr.Dataset) -> RateResult:
     coin_pulses : NDArray
         Total coincidence pulses.
     """
-    spin_number, _ = get_spin_and_duration(aux, rates["shcoarse"].values)
+    spin_number, _duration = get_spin_and_duration(aux, rates["shcoarse"].values)
 
     # Top coin pulses
     top_coin_pulses = np.stack(

From 346ed06712c271e520b283b569390f39423091d3 Mon Sep 17 00:00:00 2001
From: Luisa <luisa.coakley@lasp.colorado.edu>
Date: Wed, 17 Dec 2025 13:00:25 -0700
Subject: [PATCH 3/8] fix test

---
 .../ultra/unit/test_ultra_l1c_pset_bins.py    | 23 ++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/imap_processing/tests/ultra/unit/test_ultra_l1c_pset_bins.py b/imap_processing/tests/ultra/unit/test_ultra_l1c_pset_bins.py
index 9cd191cec..8aab16049 100644
--- a/imap_processing/tests/ultra/unit/test_ultra_l1c_pset_bins.py
+++ b/imap_processing/tests/ultra/unit/test_ultra_l1c_pset_bins.py
@@ -436,6 +436,22 @@ def test_get_spacecraft_background_rates(
     "Tests calculate_background_rates function."
     # Simulate a spin table from MET = 0 to MET = 141 * 15 seconds
     use_fake_spin_data_for_time(start_met=0, end_met=141 * 15)
+
+    # Should be evenly spaced spins of 15 seconds each except the first one has 14.
+    num_spins = 15
+    spin_start_times = np.concatenate([[0], np.arange(14, 222, num_spins)]) + 445015651
+    spin_numbers = np.arange(127, 142)
+    num_spins = len(spin_numbers)
+
+    aux_ds = xr.Dataset(
+        data_vars={
+            "timespinstart": ("epoch", spin_start_times),
+            "duration": ("epoch", np.full(num_spins, 15)),
+            "spinnumber": ("epoch", spin_numbers),
+        },
+        coords={"epoch": ("epoch", np.arange(num_spins))},
+    )
+
     df = pd.read_csv(rates_l1_test_path)
 
     rates = {
@@ -464,7 +480,12 @@ def test_get_spacecraft_background_rates(
     goodtimes_spin_number = np.array([130, 131])
 
     background_rates = get_spacecraft_background_rates(
-        rates, "ultra45", ancillary_files, energy_bin_edges, goodtimes_spin_number
+        rates,
+        aux_ds,
+        "ultra45",
+        ancillary_files,
+        energy_bin_edges,
+        goodtimes_spin_number,
     )
 
     assert background_rates.shape == (len(energy_bin_edges), hp.nside2npix(128))

From 87169b9d1c79f574fb7ea40c583361db0058413f Mon Sep 17 00:00:00 2001
From: Luisa <luisa.coakley@lasp.colorado.edu>
Date: Wed, 17 Dec 2025 13:43:54 -0700
Subject: [PATCH 4/8] test fixes

---
 imap_processing/tests/ultra/unit/test_ultra_l1c.py | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/imap_processing/tests/ultra/unit/test_ultra_l1c.py b/imap_processing/tests/ultra/unit/test_ultra_l1c.py
index 2f1614e1c..1889fdc9d 100644
--- a/imap_processing/tests/ultra/unit/test_ultra_l1c.py
+++ b/imap_processing/tests/ultra/unit/test_ultra_l1c.py
@@ -123,6 +123,8 @@ def test_ultra_l1c_error(mock_data_l1b_dict):
 def test_calculate_spacecraft_pset_with_cdf(
     ancillary_files,
     rates_dataset,
+    deadtime_datasets,
+    aux_dataset,
     imap_ena_sim_metakernel,
     use_fake_spin_data_for_time,
     mock_spacecraft_pointing_lookups,
@@ -186,7 +188,9 @@ def test_calculate_spacecraft_pset_with_cdf(
         "imap_ultra_l1b_45sensor-de": dataset,
         "imap_ultra_l1b_45sensor-extendedspin": dataset,  # placeholder
         "imap_ultra_l1b_45sensor-goodtimes": dataset,  # placeholder
-        "imap_ultra_l1a_45sensor-rates": rates_dataset,
+        "imap_ultra_l1a_45sensor-rates": deadtime_datasets["rates"],
+        "imap_ultra_l1a_45sensor-aux": aux_dataset,
+        "imap_ultra_l1a_45sensor-params": deadtime_datasets["params"],
     }
     with (
         mock.patch(
@@ -215,7 +219,8 @@ def test_calculate_helio_pset_with_cdf(
     ancillary_files,
     imap_ena_sim_metakernel,
     mock_helio_pointing_lookups,
-    rates_dataset,
+    deadtime_datasets,
+    aux_dataset,
     use_fake_spin_data_for_time,
 ):
     """Tests ultra_l1c function with imported test data."""
@@ -281,6 +286,8 @@ def test_calculate_helio_pset_with_cdf(
             }
         ),  # placeholder
         "imap_ultra_l1a_45sensor-rates": rates_dataset,
+        "imap_ultra_l1a_45sensor-aux": aux_dataset,
+        "imap_ultra_l1a_45sensor-params": deadtime_datasets["params"],
     }
     n_pix = hp.nside2npix(32)
     mock_eff = np.ones((46, n_pix))

From 799589ef2707db69a57558080982b887bb8ef9db Mon Sep 17 00:00:00 2001
From: Luisa <luisa.coakley@lasp.colorado.edu>
Date: Wed, 17 Dec 2025 14:13:39 -0700
Subject: [PATCH 5/8] use rates fixture

---
 imap_processing/tests/ultra/unit/test_ultra_l1c.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/imap_processing/tests/ultra/unit/test_ultra_l1c.py b/imap_processing/tests/ultra/unit/test_ultra_l1c.py
index 1889fdc9d..5450aadfa 100644
--- a/imap_processing/tests/ultra/unit/test_ultra_l1c.py
+++ b/imap_processing/tests/ultra/unit/test_ultra_l1c.py
@@ -221,6 +221,7 @@ def test_calculate_helio_pset_with_cdf(
     mock_helio_pointing_lookups,
     deadtime_datasets,
     aux_dataset,
+    rates_dataset,
     use_fake_spin_data_for_time,
 ):
     """Tests ultra_l1c function with imported test data."""

From 39384684e6f58de287c416843ac04336d7e94ca7 Mon Sep 17 00:00:00 2001
From: Luisa <luisa.coakley@lasp.colorado.edu>
Date: Wed, 17 Dec 2025 14:50:06 -0700
Subject: [PATCH 6/8] fix tests

---
 imap_processing/tests/ultra/unit/test_spacecraft_pset.py | 9 +++++++++
 imap_processing/tests/ultra/unit/test_ultra_l1c.py       | 3 ++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/imap_processing/tests/ultra/unit/test_spacecraft_pset.py b/imap_processing/tests/ultra/unit/test_spacecraft_pset.py
index 22f3b72be..d2d7e7fae 100644
--- a/imap_processing/tests/ultra/unit/test_spacecraft_pset.py
+++ b/imap_processing/tests/ultra/unit/test_spacecraft_pset.py
@@ -31,6 +31,8 @@
 @pytest.mark.external_test_data
 @pytest.mark.external_kernel
 def test_calculate_spacecraft_pset(
+    deadtime_datasets,
+    aux_dataset,
     rates_dataset,
     imap_ena_sim_metakernel,
     use_fake_spin_data_for_time,
@@ -102,6 +104,8 @@ def test_calculate_spacecraft_pset(
             test_l1b_de_dataset,
             test_l1b_de_dataset,  # placeholder for goodtimes_dataset
             rates_dataset,
+            aux_dataset,
+            deadtime_datasets["params"],
             "imap_ultra_l1c_45sensor-spacecraftpset",
             ancillary_files,
             45,
@@ -116,6 +120,8 @@ def test_calculate_spacecraft_pset(
 @pytest.mark.external_kernel
 def test_calculate_spacecraft_pset_with_cdf(
     ancillary_files,
+    deadtime_datasets,
+    aux_dataset,
     rates_dataset,
     imap_ena_sim_metakernel,
     use_fake_spin_data_for_time,
@@ -186,6 +192,9 @@ def test_calculate_spacecraft_pset_with_cdf(
                 dataset,
                 dataset,  # placeholder for goodtimes_dataset
                 rates_dataset,
+                rates_dataset,
+                aux_dataset,
+                deadtime_datasets["params"],
                 "imap_ultra_l1c_45sensor-spacecraftpset",
                 ancillary_files,
                 45,
diff --git a/imap_processing/tests/ultra/unit/test_ultra_l1c.py b/imap_processing/tests/ultra/unit/test_ultra_l1c.py
index 5450aadfa..7fd8e3693 100644
--- a/imap_processing/tests/ultra/unit/test_ultra_l1c.py
+++ b/imap_processing/tests/ultra/unit/test_ultra_l1c.py
@@ -124,6 +124,7 @@ def test_calculate_spacecraft_pset_with_cdf(
     ancillary_files,
     rates_dataset,
     deadtime_datasets,
+    rates_dataset,
     aux_dataset,
     imap_ena_sim_metakernel,
     use_fake_spin_data_for_time,
@@ -188,7 +189,7 @@ def test_calculate_spacecraft_pset_with_cdf(
         "imap_ultra_l1b_45sensor-de": dataset,
         "imap_ultra_l1b_45sensor-extendedspin": dataset,  # placeholder
         "imap_ultra_l1b_45sensor-goodtimes": dataset,  # placeholder
-        "imap_ultra_l1a_45sensor-rates": deadtime_datasets["rates"],
+        "imap_ultra_l1a_45sensor-rates": rates_dataset,
         "imap_ultra_l1a_45sensor-aux": aux_dataset,
         "imap_ultra_l1a_45sensor-params": deadtime_datasets["params"],
     }

From 1961b3189210b81235b710acdefd8c1b2209d2c2 Mon Sep 17 00:00:00 2001
From: Luisa <luisa.coakley@lasp.colorado.edu>
Date: Thu, 18 Dec 2025 10:43:59 -0700
Subject: [PATCH 7/8] pr comments

---
 .../tests/ultra/unit/test_spacecraft_pset.py  | 13 +++++-------
 .../ultra/unit/test_ultra_l1b_culling.py      |  2 +-
 .../ultra/unit/test_ultra_l1b_extended.py     |  2 +-
 .../tests/ultra/unit/test_ultra_l1c.py        | 20 +++++++++----------
 .../ultra/l1b/ultra_l1b_extended.py           |  6 +++---
 imap_processing/ultra/l1c/helio_pset.py       |  2 +-
 imap_processing/ultra/l1c/ultra_l1c.py        |  3 ---
 7 files changed, 20 insertions(+), 28 deletions(-)

diff --git a/imap_processing/tests/ultra/unit/test_spacecraft_pset.py b/imap_processing/tests/ultra/unit/test_spacecraft_pset.py
index d2d7e7fae..a3624e264 100644
--- a/imap_processing/tests/ultra/unit/test_spacecraft_pset.py
+++ b/imap_processing/tests/ultra/unit/test_spacecraft_pset.py
@@ -31,7 +31,6 @@
 @pytest.mark.external_test_data
 @pytest.mark.external_kernel
 def test_calculate_spacecraft_pset(
-    deadtime_datasets,
     aux_dataset,
     rates_dataset,
     imap_ena_sim_metakernel,
@@ -42,10 +41,11 @@ def test_calculate_spacecraft_pset(
     """Tests calculate_spacecraft_pset function."""
     # Simulate a spin table from MET = 0 to MET = 141 * 15 seconds
     use_fake_spin_data_for_time(start_met=0, end_met=141 * 15)
-    # Ensure rate dataset has correct time range
-    rates_dataset.shcoarse.data = np.linspace(
-        0, 141 * 15, len(rates_dataset.shcoarse.data)
-    )
+    # Ensure rate and aux data have the correct time range
+    t_rates = np.linspace(0, 141 * 15, len(rates_dataset.shcoarse.data))
+    rates_dataset.shcoarse.data = t_rates
+    aux_dataset.timespinstart.data = t_rates[: len(aux_dataset.timespinstart.data)]
+    aux_dataset.timespinstart.data[-1] = t_rates[-1]
     # This is just setting up the data so that it is in the format of l1b_de_dataset.
     test_path = TEST_PATH / "ultra-90_raw_event_data_shortened.csv"
     df = pd.read_csv(test_path)
@@ -105,7 +105,6 @@ def test_calculate_spacecraft_pset(
             test_l1b_de_dataset,  # placeholder for goodtimes_dataset
             rates_dataset,
             aux_dataset,
-            deadtime_datasets["params"],
             "imap_ultra_l1c_45sensor-spacecraftpset",
             ancillary_files,
             45,
@@ -120,7 +119,6 @@ def test_calculate_spacecraft_pset(
 @pytest.mark.external_kernel
 def test_calculate_spacecraft_pset_with_cdf(
     ancillary_files,
-    deadtime_datasets,
     aux_dataset,
     rates_dataset,
     imap_ena_sim_metakernel,
@@ -194,7 +192,6 @@ def test_calculate_spacecraft_pset_with_cdf(
                 rates_dataset,
                 rates_dataset,
                 aux_dataset,
-                deadtime_datasets["params"],
                 "imap_ultra_l1c_45sensor-spacecraftpset",
                 ancillary_files,
                 45,
diff --git a/imap_processing/tests/ultra/unit/test_ultra_l1b_culling.py b/imap_processing/tests/ultra/unit/test_ultra_l1b_culling.py
index 7daaa0279..0c5cbac2d 100644
--- a/imap_processing/tests/ultra/unit/test_ultra_l1b_culling.py
+++ b/imap_processing/tests/ultra/unit/test_ultra_l1b_culling.py
@@ -171,7 +171,7 @@ def test_compare_aux_univ_spin_table(use_fake_spin_data_for_time, faux_aux_datas
     assert np.all(result == expected)
 
 
-def test_get_duration(rates_l1_test_path, use_fake_spin_data_for_time, aux_test_path):
+def test_get_duration(rates_l1_test_path, use_fake_spin_data_for_time):
     """Tests get_duration function."""
     use_fake_spin_data_for_time(start_met=0, end_met=141 * 15)
     df = pd.read_csv(rates_l1_test_path)
diff --git a/imap_processing/tests/ultra/unit/test_ultra_l1b_extended.py b/imap_processing/tests/ultra/unit/test_ultra_l1b_extended.py
index 5cc1fdc79..25c79ce20 100644
--- a/imap_processing/tests/ultra/unit/test_ultra_l1b_extended.py
+++ b/imap_processing/tests/ultra/unit/test_ultra_l1b_extended.py
@@ -561,7 +561,7 @@ def test_get_eventtimes(test_fixture, aux_dataset):
 
 @pytest.mark.external_test_data
 def test_get_spin_and_duration(test_fixture, aux_dataset):
-    """Tests get_eventtimes function."""
+    """Tests get_spin_and_duration function."""
     df_filt, _, _, de_dataset = test_fixture
 
     spin_number, spin_duration = get_spin_and_duration(
diff --git a/imap_processing/tests/ultra/unit/test_ultra_l1c.py b/imap_processing/tests/ultra/unit/test_ultra_l1c.py
index 7fd8e3693..295613f9e 100644
--- a/imap_processing/tests/ultra/unit/test_ultra_l1c.py
+++ b/imap_processing/tests/ultra/unit/test_ultra_l1c.py
@@ -123,8 +123,6 @@ def test_ultra_l1c_error(mock_data_l1b_dict):
 def test_calculate_spacecraft_pset_with_cdf(
     ancillary_files,
     rates_dataset,
-    deadtime_datasets,
-    rates_dataset,
     aux_dataset,
     imap_ena_sim_metakernel,
     use_fake_spin_data_for_time,
@@ -140,10 +138,11 @@ def test_calculate_spacecraft_pset_with_cdf(
     df_subset = df[df["pointing_number"] == pointing].copy()
 
     de_dict = {}
-    # Ensure rate dataset has correct time range
-    rates_dataset.shcoarse.data = np.linspace(
-        0, 141 * 15, len(rates_dataset.shcoarse.data)
-    )
+    # Ensure rate and aux data are in the correct time window
+    t_rates = np.linspace(0, 141 * 15, len(rates_dataset.shcoarse.data))
+    rates_dataset.shcoarse.data = t_rates
+    aux_dataset.timespinstart.data = t_rates[: len(aux_dataset.timespinstart.data)]
+    aux_dataset.timespinstart.data[-1] = t_rates[-1]
     de_dict["epoch"] = df_subset["epoch"].values
     species_bin = np.full(len(df_subset), 1, dtype=np.uint8)
 
@@ -191,7 +190,6 @@ def test_calculate_spacecraft_pset_with_cdf(
         "imap_ultra_l1b_45sensor-goodtimes": dataset,  # placeholder
         "imap_ultra_l1a_45sensor-rates": rates_dataset,
         "imap_ultra_l1a_45sensor-aux": aux_dataset,
-        "imap_ultra_l1a_45sensor-params": deadtime_datasets["params"],
     }
     with (
         mock.patch(
@@ -220,7 +218,6 @@ def test_calculate_helio_pset_with_cdf(
     ancillary_files,
     imap_ena_sim_metakernel,
     mock_helio_pointing_lookups,
-    deadtime_datasets,
     aux_dataset,
     rates_dataset,
     use_fake_spin_data_for_time,
@@ -233,8 +230,10 @@ def test_calculate_helio_pset_with_cdf(
     )
     df = pd.read_csv(TEST_PATH / "IMAP-Ultra45_r1_L1_V0_shortened.csv")
 
-    # Ensure rate dataset has correct time range
-    rates_dataset.shcoarse.data += 56970124
+    # Ensure rate and aux data are in the correct time window
+    t_off = 56970125
+    rates_dataset.shcoarse.data += t_off
+    aux_dataset.timespinstart.data += t_off
     # Select a single pointing number
     pointing = 0
     df_subset = df[df["pointing_number"] == pointing].copy()
@@ -289,7 +288,6 @@ def test_calculate_helio_pset_with_cdf(
         ),  # placeholder
         "imap_ultra_l1a_45sensor-rates": rates_dataset,
         "imap_ultra_l1a_45sensor-aux": aux_dataset,
-        "imap_ultra_l1a_45sensor-params": deadtime_datasets["params"],
     }
     n_pix = hp.nside2npix(32)
     mock_eff = np.ones((46, n_pix))
diff --git a/imap_processing/ultra/l1b/ultra_l1b_extended.py b/imap_processing/ultra/l1b/ultra_l1b_extended.py
index 3d61de725..251940a39 100644
--- a/imap_processing/ultra/l1b/ultra_l1b_extended.py
+++ b/imap_processing/ultra/l1b/ultra_l1b_extended.py
@@ -923,7 +923,7 @@ def get_spin_start_indices(aux_dataset: xr.Dataset, de_event_met: NDArray) -> ND
 
     Parameters
     ----------
-    aux_dataset : numpy.ndarray
+    aux_dataset : xarray.Dataset
         Auxiliary dataset containing spin information.
     de_event_met : numpy.ndarray
         Direct event MET.
@@ -968,7 +968,7 @@ def get_event_times(
 
     Parameters
     ----------
-    aux_dataset : numpy.ndarray
+    aux_dataset : xarray.Dataset
         Auxiliary dataset containing spin information.
     phase_angle : numpy.ndarray
         Phase angle.
@@ -1016,7 +1016,7 @@ def get_spin_and_duration(
 
     Parameters
     ----------
-    aux_dataset : numpy.ndarray
+    aux_dataset : xarray.Dataset
         Auxiliary dataset containing spin information.
     de_event_met : numpy.ndarray
         Direct event MET.
diff --git a/imap_processing/ultra/l1c/helio_pset.py b/imap_processing/ultra/l1c/helio_pset.py
index 64c0d8862..5f699076a 100644
--- a/imap_processing/ultra/l1c/helio_pset.py
+++ b/imap_processing/ultra/l1c/helio_pset.py
@@ -39,7 +39,7 @@ def calculate_helio_pset(
     de_dataset: xr.Dataset,
     goodtimes_dataset: xr.Dataset,
     rates_dataset: xr.Dataset,
-    aux_dataset: xr.Dataset,,
+    aux_dataset: xr.Dataset,
     name: str,
     ancillary_files: dict,
     instrument_id: int,
diff --git a/imap_processing/ultra/l1c/ultra_l1c.py b/imap_processing/ultra/l1c/ultra_l1c.py
index 1456d1d66..daccfaf37 100644
--- a/imap_processing/ultra/l1c/ultra_l1c.py
+++ b/imap_processing/ultra/l1c/ultra_l1c.py
@@ -54,14 +54,12 @@ def ultra_l1c(
             and f"imap_ultra_l1b_{instrument_id}sensor-de" in data_dict
             and f"imap_ultra_l1a_{instrument_id}sensor-rates" in data_dict
             and f"imap_ultra_l1a_{instrument_id}sensor-aux" in data_dict
-            and f"imap_ultra_l1a_{instrument_id}sensor-params" in data_dict
         ):
             spacecraft_pset = calculate_spacecraft_pset(
                 data_dict[f"imap_ultra_l1b_{instrument_id}sensor-de"],
                 data_dict[f"imap_ultra_l1b_{instrument_id}sensor-goodtimes"],
                 data_dict[f"imap_ultra_l1a_{instrument_id}sensor-rates"],
                 data_dict[f"imap_ultra_l1a_{instrument_id}sensor-aux"],
-                data_dict[f"imap_ultra_l1a_{instrument_id}sensor-params"],
                 f"imap_ultra_l1c_{instrument_id}sensor-spacecraftpset",
                 ancillary_files,
                 instrument_id,
@@ -73,7 +71,6 @@ def ultra_l1c(
                 data_dict[f"imap_ultra_l1b_{instrument_id}sensor-goodtimes"],
                 data_dict[f"imap_ultra_l1a_{instrument_id}sensor-rates"],
                 data_dict[f"imap_ultra_l1a_{instrument_id}sensor-aux"],
-                data_dict[f"imap_ultra_l1a_{instrument_id}sensor-params"],
                 f"imap_ultra_l1c_{instrument_id}sensor-spacecraftpset-nonproton",
                 ancillary_files,
                 instrument_id,

From fb84bcfe00f85d61065f05042c89b09f88ddc570 Mon Sep 17 00:00:00 2001
From: Luisa <luisa.coakley@lasp.colorado.edu>
Date: Thu, 18 Dec 2025 10:53:34 -0700
Subject: [PATCH 8/8] fix aux data time

---
 .../tests/ultra/unit/test_helio_pset.py           |  3 ++-
 .../tests/ultra/unit/test_spacecraft_pset.py      | 15 +++++++++------
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/imap_processing/tests/ultra/unit/test_helio_pset.py b/imap_processing/tests/ultra/unit/test_helio_pset.py
index fdeca17c6..6a4390cc2 100644
--- a/imap_processing/tests/ultra/unit/test_helio_pset.py
+++ b/imap_processing/tests/ultra/unit/test_helio_pset.py
@@ -16,7 +16,7 @@
 
 @pytest.mark.skip(reason="Long running test for validation purposes.")
 def test_validate_exposure_time_and_sensitivities(
-    ancillary_files, rates_dataset, imap_ena_sim_metakernel
+    ancillary_files, rates_dataset, imap_ena_sim_metakernel, aux_dataset
 ):
     """Validates exposure time and sensitivities for ebin 0."""
     sens_filename = "SENS-IMAP_ULTRA_90-IMAP_DPS-HELIO-nside32-ebin0.csv"
@@ -91,6 +91,7 @@ def test_validate_exposure_time_and_sensitivities(
             l1b_de,
             dataset,
             rates_dataset,
+            aux_dataset,
             "imap_ultra_l1c_90sensor-heliopset",
             ancillary_files,
             90,
diff --git a/imap_processing/tests/ultra/unit/test_spacecraft_pset.py b/imap_processing/tests/ultra/unit/test_spacecraft_pset.py
index a3624e264..ac72830e6 100644
--- a/imap_processing/tests/ultra/unit/test_spacecraft_pset.py
+++ b/imap_processing/tests/ultra/unit/test_spacecraft_pset.py
@@ -138,10 +138,11 @@ def test_calculate_spacecraft_pset_with_cdf(
 
         de_dict["epoch"] = df_subset["epoch"].values
         species_bin = np.full(len(df_subset), 1, dtype=np.uint8)
-        # Ensure rate dataset has correct time range
-        rates_dataset.shcoarse.data = np.linspace(
-            0, 141 * 15, len(rates_dataset.shcoarse.data)
-        )
+        # Ensure rate and aux data have the correct time range
+        t_rates = np.linspace(0, 141 * 15, len(rates_dataset.shcoarse.data))
+        rates_dataset.shcoarse.data = t_rates
+        aux_dataset.timespinstart.data = t_rates[: len(aux_dataset.timespinstart.data)]
+        aux_dataset.timespinstart.data[-1] = t_rates[-1]
         # PosYSlit is True for left (start_type = 1)
         # PosYSlit is False for right (start_type = 2)
         start_type = np.where(df_subset["PosYSlit"].values, 1, 2)
@@ -190,7 +191,6 @@ def test_calculate_spacecraft_pset_with_cdf(
                 dataset,
                 dataset,  # placeholder for goodtimes_dataset
                 rates_dataset,
-                rates_dataset,
                 aux_dataset,
                 "imap_ultra_l1c_45sensor-spacecraftpset",
                 ancillary_files,
@@ -205,7 +205,9 @@ def test_calculate_spacecraft_pset_with_cdf(
 
 
 @pytest.mark.skip(reason="Long running test for validation purposes.")
-def test_validate_exposure_time_and_sensitivities(ancillary_files, rates_dataset):
+def test_validate_exposure_time_and_sensitivities(
+    ancillary_files, rates_dataset, aux_dataset
+):
     """Validates exposure time and sensitivities for ebin 0."""
     test_data = [
         (
@@ -302,6 +304,7 @@ def test_validate_exposure_time_and_sensitivities(ancillary_files, rates_dataset
             l1b_de,
             dataset,
             rates_dataset,
+            aux_dataset,
             "imap_ultra_l1c_90sensor-spacecraftpset",
             ancillary_files,
             90,