diff --git a/explore/app/src/main/scala/explore/config/BasicConfigurationPanel.scala b/explore/app/src/main/scala/explore/config/BasicConfigurationPanel.scala
index fb7422446f..421194ff9c 100644
--- a/explore/app/src/main/scala/explore/config/BasicConfigurationPanel.scala
+++ b/explore/app/src/main/scala/explore/config/BasicConfigurationPanel.scala
@@ -28,8 +28,8 @@ import japgolly.scalajs.react.*
 import japgolly.scalajs.react.vdom.html_<^.*
 import lucuma.core.enums.CalibrationRole
 import lucuma.core.enums.ScienceMode
+import lucuma.core.math.Coordinates
 import lucuma.core.model.ConstraintSet
-import lucuma.core.model.CoordinatesAt
 import lucuma.core.model.User
 import lucuma.core.util.NewBoolean
 import lucuma.core.util.Timestamp
@@ -51,7 +51,7 @@ case class BasicConfigurationPanel(
   selectedConfig:      View[ConfigSelection],
   constraints:         ConstraintSet,
   itcTargets:          EitherNec[ItcTargetProblem, NonEmptyList[ItcTarget]],
-  baseCoordinates:     Option[CoordinatesAt],
+  baseCoordinates:     Option[Coordinates],
   calibrationRole:     Option[CalibrationRole],
   createConfig:        IO[Unit],
   confMatrix:          ScienceModes,
diff --git a/explore/app/src/main/scala/explore/config/ConfigurationTile.scala b/explore/app/src/main/scala/explore/config/ConfigurationTile.scala
index c960a9deb0..99506b0e81 100644
--- a/explore/app/src/main/scala/explore/config/ConfigurationTile.scala
+++ b/explore/app/src/main/scala/explore/config/ConfigurationTile.scala
@@ -48,7 +48,7 @@ import explore.undo.*
 import japgolly.scalajs.react.*
 import japgolly.scalajs.react.vdom.html_<^.*
 import lucuma.core.math.Angle
-import lucuma.core.model.CoordinatesAt
+import lucuma.core.math.Coordinates
 import lucuma.core.model.PosAngleConstraint
 import lucuma.core.model.Program
 import lucuma.core.model.User
@@ -72,7 +72,7 @@ object ConfigurationTile:
     requirements:             UndoSetter[ScienceRequirements],
     pacAndMode:               UndoSetter[PosAngleConstraintAndObsMode],
     scienceTargetIds:         AsterismIds,
-    baseCoordinates:          Option[CoordinatesAt],
+    baseCoordinates:          Option[Coordinates],
     obsConf:                  ObsConfiguration,
     selectedConfig:           View[ConfigSelection],
     revertedInstrumentConfig: List[ItcInstrumentConfig], // configuration rows selected if reverted
@@ -206,7 +206,7 @@ object ConfigurationTile:
     pacAndMode:               UndoSetter[PosAngleConstraintAndObsMode],
     obsConf:                  ObsConfiguration,
     itcTargets:               EitherNec[ItcTargetProblem, NonEmptyList[ItcTarget]],
-    baseCoordinates:          Option[CoordinatesAt],
+    baseCoordinates:          Option[Coordinates],
     selectedConfig:           View[ConfigSelection],
     revertedInstrumentConfig: List[ItcInstrumentConfig],
     modes:                    ScienceModes,
diff --git a/explore/app/src/main/scala/explore/config/ImagingModesTable.scala b/explore/app/src/main/scala/explore/config/ImagingModesTable.scala
index b8cebb7184..432fa1f8d2 100644
--- a/explore/app/src/main/scala/explore/config/ImagingModesTable.scala
+++ b/explore/app/src/main/scala/explore/config/ImagingModesTable.scala
@@ -34,11 +34,11 @@ import lucuma.core.enums.*
 import lucuma.core.math.Angle
 import lucuma.core.math.BoundedInterval
 import lucuma.core.math.BoundedInterval.*
+import lucuma.core.math.Coordinates
 import lucuma.core.math.SignalToNoise
 import lucuma.core.math.Wavelength
 import lucuma.core.math.WavelengthDelta
 import lucuma.core.model.ConstraintSet
-import lucuma.core.model.CoordinatesAt
 import lucuma.core.model.ExposureTimeMode
 import lucuma.core.model.User
 import lucuma.core.syntax.all.*
@@ -64,7 +64,7 @@ final case class ImagingModesTable(
   matrix:              ImagingModesMatrix,
   constraints:         ConstraintSet,
   targets:             EitherNec[ItcTargetProblem, NonEmptyList[ItcTarget]],
-  baseCoordinates:     Option[CoordinatesAt],
+  baseCoordinates:     Option[Coordinates],
   customSedTimestamps: List[Timestamp],
   units:               WavelengthUnits,
   targetView:          View[Option[ItcTarget]]
diff --git a/explore/app/src/main/scala/explore/config/SpectroscopyModesTable.scala b/explore/app/src/main/scala/explore/config/SpectroscopyModesTable.scala
index 8b2ab24250..1e72ad01be 100644
--- a/explore/app/src/main/scala/explore/config/SpectroscopyModesTable.scala
+++ b/explore/app/src/main/scala/explore/config/SpectroscopyModesTable.scala
@@ -64,7 +64,7 @@ case class SpectroscopyModesTable(
   spectroscopyRequirements: ScienceRequirements.Spectroscopy,
   constraints:              ConstraintSet,
   targets:                  EitherNec[ItcTargetProblem, NonEmptyList[ItcTarget]],
-  baseCoordinates:          Option[CoordinatesAt],
+  baseCoordinates:          Option[Coordinates],
   matrix:                   SpectroscopyModesMatrix,
   customSedTimestamps:      List[Timestamp],
   units:                    WavelengthUnits
@@ -246,7 +246,7 @@ private object SpectroscopyModesTable extends ModesTableCommon:
                             (props.matrix,
                              props.exposureTimeMode,
                              props.spectroscopyRequirements,
-                             props.baseCoordinates.map(_.value.dec),
+                             props.baseCoordinates.map(_.dec),
                              itcResults.get.cache.size,
                              props.targets,
                              props.constraints,
diff --git a/explore/app/src/main/scala/explore/plots/ElevationPlotTile.scala b/explore/app/src/main/scala/explore/plots/ElevationPlotTile.scala
index d22b2301c9..85ff723a90 100644
--- a/explore/app/src/main/scala/explore/plots/ElevationPlotTile.scala
+++ b/explore/app/src/main/scala/explore/plots/ElevationPlotTile.scala
@@ -21,12 +21,13 @@ import explore.model.display.given
 import explore.model.enums.PlotRange
 import explore.model.enums.TimeDisplay
 import explore.model.enums.Visible
+import explore.model.extensions.*
 import japgolly.scalajs.react.*
 import japgolly.scalajs.react.vdom.html_<^.*
 import lucuma.core.enums.Site
 import lucuma.core.enums.TimingWindowInclusion
 import lucuma.core.math.BoundedInterval
-import lucuma.core.model.CoordinatesAt
+import lucuma.core.math.Coordinates
 import lucuma.core.model.Semester
 import lucuma.core.model.TimingWindow
 import lucuma.core.model.User
@@ -213,11 +214,11 @@ object ElevationPlotTile:
                 )
               case PlotRange.Semester                  =>
                 props.plotData.value.headOption.map { case (_, data) =>
-                  val coords: CoordinatesAt =
+                  val coords: Coordinates =
                     data.tracking
                       .at(semesterView.get.start.atSite(siteView.get).toInstant)
                       .getOrElse:
-                        CoordinatesAt(data.tracking.baseCoordinates)
+                        data.tracking.baseCoordinates
 
                   SemesterPlot(
                     plotOptions.get,
diff --git a/explore/app/src/main/scala/explore/plots/ObjectPlotData.scala b/explore/app/src/main/scala/explore/plots/ObjectPlotData.scala
index a5e45ea6eb..e406d08f7f 100644
--- a/explore/app/src/main/scala/explore/plots/ObjectPlotData.scala
+++ b/explore/app/src/main/scala/explore/plots/ObjectPlotData.scala
@@ -8,13 +8,13 @@ import cats.Order
 import cats.derived.*
 import eu.timepit.refined.cats.given
 import eu.timepit.refined.types.string.NonEmptyString
+import explore.model.extensions.*
 import japgolly.scalajs.react.*
 import lucuma.core.enums.Site
 import lucuma.core.math.skycalc.SkyCalcResults
-import lucuma.core.model.CoordinatesAt
-import lucuma.core.model.ObjectTracking
 import lucuma.core.model.Observation
 import lucuma.core.model.Target
+import lucuma.core.model.Tracking
 import lucuma.core.util.NewType
 import lucuma.typed.highcharts.mod.Point
 import lucuma.typed.highcharts.mod.PointOptionsObject
@@ -37,7 +37,7 @@ trait ElevationPointWithAirmass extends Point:
 // Can wrap data for a target or an asterism.
 case class ObjectPlotData(
   name:     NonEmptyString,
-  tracking: ObjectTracking,
+  tracking: Tracking,
   sites:    List[Site]
 ) derives Eq:
   private val PlotEvery: Duration = Duration.ofMinutes(1)
@@ -51,7 +51,9 @@ case class ObjectPlotData(
         PlotEvery,
         // We are computing the coordinates at each point in time, this may be expensive
         // and could be optimized for sidereals, but it's probably necessary for non-sidereals.
-        tracking.at(_).map(_.value).getOrElse(tracking.baseCoordinates)
+        tracking
+          .at(_)
+          .getOrElse(tracking.baseCoordinates)
       )
 
 object ObjectPlotData:
diff --git a/explore/app/src/main/scala/explore/plots/ObjectPlotOptions.scala b/explore/app/src/main/scala/explore/plots/ObjectPlotOptions.scala
index 46c9a2d8ca..7f4018eb36 100644
--- a/explore/app/src/main/scala/explore/plots/ObjectPlotOptions.scala
+++ b/explore/app/src/main/scala/explore/plots/ObjectPlotOptions.scala
@@ -9,16 +9,16 @@ import cats.syntax.all.*
 import explore.model.ElevationPlotScheduling
 import explore.model.enums.PlotRange
 import explore.model.enums.TimeDisplay
+import explore.model.extensions.*
 import japgolly.scalajs.react.ReactCats.*
 import japgolly.scalajs.react.Reusability
 import lucuma.core.enums.Site
 import lucuma.core.enums.TwilightType
 import lucuma.core.math.BoundedInterval
 import lucuma.core.math.Coordinates
-import lucuma.core.model.CoordinatesAt
-import lucuma.core.model.ObjectTracking
 import lucuma.core.model.ObservingNight
 import lucuma.core.model.Semester
+import lucuma.core.model.Tracking
 import monocle.Focus
 import org.typelevel.cats.time.given
 
@@ -101,13 +101,13 @@ object ObjectPlotOptions:
   def default(
     predefinedSite:  Option[Site],
     observationTime: Option[Instant],
-    tracking:        Option[ObjectTracking]
+    tracking:        Option[Tracking]
   ) =
     val coords: Option[Coordinates] =
       for
         time <- observationTime
         t    <- tracking
-      yield t.at(time).map(_.value).getOrElse(t.baseCoordinates)
+      yield t.at(time).getOrElse(t.baseCoordinates)
     val site: Site                  =
       predefinedSite
         .orElse:
diff --git a/explore/app/src/main/scala/explore/plots/SemesterPlot.scala b/explore/app/src/main/scala/explore/plots/SemesterPlot.scala
index 111d1c84c9..fc2ef450b2 100644
--- a/explore/app/src/main/scala/explore/plots/SemesterPlot.scala
+++ b/explore/app/src/main/scala/explore/plots/SemesterPlot.scala
@@ -14,7 +14,7 @@ import explore.model.WorkerClients.PlotClient
 import fs2.Stream
 import japgolly.scalajs.react.*
 import lucuma.core.math.BoundedInterval
-import lucuma.core.model.CoordinatesAt
+import lucuma.core.math.Coordinates
 import lucuma.core.util.time.format.GppDateFormatter
 import lucuma.react.common.ReactFnProps
 import lucuma.react.highcharts.Chart
@@ -36,7 +36,7 @@ import js.JSConverters.*
 
 case class SemesterPlot(
   options:          ObjectPlotOptions,
-  coords:           CoordinatesAt,
+  coords:           Coordinates,
   excludeIntervals: List[BoundedInterval[Instant]]
 ) extends ReactFnProps(SemesterPlot.component)
 
@@ -55,7 +55,7 @@ object SemesterPlot:
       .useState(none[Chart_]) // chart handler (chartOpt)
       .useEffectStreamResourceWithDepsBy((props, _, chartOpt) =>
         chartOpt.value.map: chart =>
-          (props.options.semester, props.options.site, props.coords.value, Reusable.always(chart))
+          (props.options.semester, props.options.site, props.coords, Reusable.always(chart))
       ): (_, ctx, _) =>
         _.map { (semester, site, coords, chart) =>
           import ctx.given
diff --git a/explore/app/src/main/scala/explore/tabs/ObsTabTiles.scala b/explore/app/src/main/scala/explore/tabs/ObsTabTiles.scala
index a46cef515a..1fe573857a 100644
--- a/explore/app/src/main/scala/explore/tabs/ObsTabTiles.scala
+++ b/explore/app/src/main/scala/explore/tabs/ObsTabTiles.scala
@@ -56,15 +56,15 @@ import lucuma.core.enums.CalibrationRole
 import lucuma.core.enums.ProgramType
 import lucuma.core.enums.Site
 import lucuma.core.math.Angle
+import lucuma.core.math.Coordinates
 import lucuma.core.math.Offset
 import lucuma.core.math.skycalc.averageParallacticAngle
 import lucuma.core.model.ConstraintSet
-import lucuma.core.model.CoordinatesAt
 import lucuma.core.model.IntCentiPercent
-import lucuma.core.model.ObjectTracking
 import lucuma.core.model.PosAngleConstraint
 import lucuma.core.model.Program
 import lucuma.core.model.Target
+import lucuma.core.model.Tracking
 import lucuma.core.optics.syntax.lens.*
 import lucuma.core.syntax.all.*
 import lucuma.core.util.TimeSpan
@@ -117,7 +117,7 @@ case class ObsTabTiles(
   val obsAttachmentAssignments: ObsAttachmentAssignmentMap =
     programSummaries.obsAttachmentAssignments
 
-  val asterismTracking: Option[ObjectTracking] =
+  val asterismTracking: Option[Tracking] =
     observation.get.asterismTracking(obsTargets)
 
   val posAngleConstraint: PosAngleConstraint = observation.get.posAngleConstraint
@@ -133,7 +133,7 @@ case class ObsTabTiles(
     NonEmptyList.fromList:
       obsTargets.toList.map((_, t) => t)
 
-  def targetCoords(obsTime: Instant): Option[CoordinatesAt] =
+  def targetCoords(obsTime: Instant): Option[Coordinates] =
     asterismAsNel
       .flatMap(asterismNel => asterismNel.baseTracking.flatMap(_.at(obsTime)))
 
@@ -150,7 +150,7 @@ case class ObsTabTiles(
     )
 
   def obsIQLikelihood(obsTime: Instant): Option[IntCentiPercent] =
-    (centralWavelength, targetCoords(obsTime).map(_.value.dec), site).mapN((cw, dec, site) =>
+    (centralWavelength, targetCoords(obsTime).map(_.dec), site).mapN((cw, dec, site) =>
       site
         .minimumAirMassFor(dec)
         .fold(IntCentiPercent.Min): airMass =>
@@ -158,7 +158,7 @@ case class ObsTabTiles(
     )
 
   def obsConditionsLikelihood(obsTime: Instant): Option[IntCentiPercent] =
-    (centralWavelength, targetCoords(obsTime).map(_.value.dec), site).mapN((cw, dec, site) =>
+    (centralWavelength, targetCoords(obsTime).map(_.dec), site).mapN((cw, dec, site) =>
       conditionsLikelihood(
         constraintSet.get.skyBackground,
         constraintSet.get.cloudExtinction.toCloudExtinction,
diff --git a/explore/app/src/main/scala/explore/tabs/TargetTabContents.scala b/explore/app/src/main/scala/explore/tabs/TargetTabContents.scala
index a557279682..ad66df4a91 100644
--- a/explore/app/src/main/scala/explore/tabs/TargetTabContents.scala
+++ b/explore/app/src/main/scala/explore/tabs/TargetTabContents.scala
@@ -38,9 +38,9 @@ import japgolly.scalajs.react.*
 import japgolly.scalajs.react.extra.router.SetRouteVia
 import japgolly.scalajs.react.vdom.html_<^.*
 import lucuma.core.enums.Site
-import lucuma.core.model.ObjectTracking
 import lucuma.core.model.Program
 import lucuma.core.model.Target
+import lucuma.core.model.Tracking
 import lucuma.core.model.User
 import lucuma.core.model.sequence.ExecutionDigest
 import lucuma.core.optics.syntax.lens.*
@@ -329,7 +329,7 @@ object TargetTabContents extends TwoPanels:
                   props.targets.get
                     .get(targetId)
                     .flatMap: targetWithId =>
-                      ObjectTracking
+                      Tracking
                         .fromTarget(targetWithId.target)
                         .map: tracking =>
                           ObjectPlotData.Id(targetId.asRight) -> ObjectPlotData(
diff --git a/explore/app/src/main/scala/explore/targeteditor/AladinCell.scala b/explore/app/src/main/scala/explore/targeteditor/AladinCell.scala
index 82dd7d6db9..93a3f9e17b 100644
--- a/explore/app/src/main/scala/explore/targeteditor/AladinCell.scala
+++ b/explore/app/src/main/scala/explore/targeteditor/AladinCell.scala
@@ -26,6 +26,7 @@ import explore.model.boopickle.*
 import explore.model.boopickle.CatalogPicklers.given
 import explore.model.enums.AgsState
 import explore.model.enums.Visible
+import explore.model.extensions.*
 import explore.model.reusability.given
 import explore.optics.ModelOptics
 import japgolly.scalajs.react.*
@@ -39,7 +40,7 @@ import lucuma.core.enums.PortDisposition
 import lucuma.core.math.Angle
 import lucuma.core.math.Coordinates
 import lucuma.core.math.Offset
-import lucuma.core.model.ObjectTracking
+import lucuma.core.model.Tracking
 import lucuma.core.model.User
 import lucuma.core.model.sequence.flamingos2.Flamingos2FpuMask
 import lucuma.react.common.*
@@ -64,7 +65,7 @@ case class AladinCell(
   uid:                User.Id,
   obsId:              Option[Observation.Id],
   asterism:           Asterism,
-  asterismTracking:   ObjectTracking,
+  asterismTracking:   Tracking,
   obsTime:            Instant,
   obsConf:            Option[ObsConfiguration],
   fullScreen:         View[AladinFullScreen],
@@ -352,7 +353,7 @@ object AladinCell extends ModelOptics with AladinCommon:
                                          props.asterism.focus.id,
                                          constraints,
                                          centralWavelength.value,
-                                         base.value,
+                                         base,
                                          props.sciencePositionsAt(vizTime),
                                          positions,
                                          p,
diff --git a/explore/app/src/main/scala/explore/targeteditor/AladinContainer.scala b/explore/app/src/main/scala/explore/targeteditor/AladinContainer.scala
index ad30553193..364bd7eb06 100644
--- a/explore/app/src/main/scala/explore/targeteditor/AladinContainer.scala
+++ b/explore/app/src/main/scala/explore/targeteditor/AladinContainer.scala
@@ -17,6 +17,7 @@ import explore.model.ConfigurationForVisualization
 import explore.model.Constants
 import explore.model.GlobalPreferences
 import explore.model.enums.Visible
+import explore.model.extensions.*
 import explore.model.reusability.given
 import japgolly.scalajs.react.*
 import japgolly.scalajs.react.Reusability.*
@@ -31,8 +32,7 @@ import lucuma.core.math.Angle
 import lucuma.core.math.Coordinates
 import lucuma.core.math.Offset
 import lucuma.core.math.Wavelength
-import lucuma.core.model.CoordinatesAt
-import lucuma.core.model.ObjectTracking
+import lucuma.core.model.Tracking
 import lucuma.react.common.Css
 import lucuma.react.common.ReactFnProps
 import lucuma.react.resizeDetector.hooks.*
@@ -49,7 +49,7 @@ import scala.concurrent.duration.*
 
 case class AladinContainer(
   asterism:               Asterism,
-  asterismTracking:       ObjectTracking,
+  asterismTracking:       Tracking,
   obsTime:                Instant,
   vizConf:                Option[ConfigurationForVisualization],
   globalPreferences:      GlobalPreferences,
@@ -84,9 +84,9 @@ object AladinContainer extends AladinCommon {
         ExploreStyles.GuideSpeedSlow
 
   private def baseAndScience(p: Props) = {
-    val base: CoordinatesAt = p.asterismTracking
+    val base: Coordinates = p.asterismTracking
       .at(p.obsTime)
-      .getOrElse(CoordinatesAt(p.asterismTracking.baseCoordinates))
+      .getOrElse(p.asterismTracking.baseCoordinates)
 
     val science = p.asterism.toSidereal
       .map(t =>
@@ -96,6 +96,7 @@ object AladinContainer extends AladinCommon {
          t.target.tracking.baseCoordinates
         )
       )
+
     (base, science)
   }
 
@@ -114,19 +115,19 @@ object AladinContainer extends AladinCommon {
         baseCoords <- useState(baseAndScience(props))
         // View coordinates base coordinates with pm correction + user panning
         currentPos <-
-          useState(baseCoords.value._1.value.offsetBy(Angle.Angle0, props.options.viewOffset))
+          useState(baseCoords.value._1.offsetBy(Angle.Angle0, props.options.viewOffset))
         // Update coordinates if asterism or obsTime changes
         _          <- useEffectWithDeps((props.asterism, props.obsTime)): _ =>
                         val (base, science) = baseAndScience(props)
                         baseCoords.setState((base, science)) *>
                           currentPos.setState:
-                            base.value.offsetBy(Angle.Angle0, props.options.viewOffset)
+                            base.offsetBy(Angle.Angle0, props.options.viewOffset)
         // Ref to the aladin component
         aladinRef  <- useState(none[Aladin])
         // If view offset changes upstream to zero, redraw
         _          <-
           useEffectWithDeps((baseCoords, props.options.viewOffset)): (_, offset) =>
-            val newCoords = baseCoords.value._1.value.offsetBy(Angle.Angle0, offset)
+            val newCoords = baseCoords.value._1.offsetBy(Angle.Angle0, offset)
             newCoords
               .map: coords =>
                 aladinRef.value
@@ -146,7 +147,7 @@ object AladinContainer extends AladinCommon {
               case ObservingModeType.Flamingos2LongSlit                                      =>
                 (Css.Empty,
                  Flamingos2Geometry.f2Geometry(
-                   baseCoords.value._1.value,
+                   baseCoords.value._1,
                    props.vizConf.flatMap(_.scienceOffsets),
                    props.vizConf.flatMap(_.acquisitionOffsets),
                    props.vizConf.map(_.posAngle),
@@ -159,7 +160,7 @@ object AladinContainer extends AladinCommon {
               case ObservingModeType.GmosNorthLongSlit | ObservingModeType.GmosSouthLongSlit =>
                 (Css.Empty,
                  GmosGeometry.gmosGeometry(
-                   baseCoords.value._1.value,
+                   baseCoords.value._1,
                    props.vizConf.flatMap(_.scienceOffsets),
                    props.vizConf.flatMap(_.acquisitionOffsets),
                    props.vizConf.map(_.posAngle),
@@ -172,7 +173,7 @@ object AladinContainer extends AladinCommon {
               case ObservingModeType.GmosNorthImaging | ObservingModeType.GmosSouthImaging   =>
                 (VisualizationStyles.GmosCcdVisible,
                  GmosGeometry.gmosGeometry(
-                   baseCoords.value._1.value,
+                   baseCoords.value._1,
                    props.vizConf.flatMap(_.scienceOffsets),
                    props.vizConf.flatMap(_.acquisitionOffsets),
                    props.vizConf.map(_.posAngle),
@@ -285,16 +286,16 @@ object AladinContainer extends AladinCommon {
                               .flatten
 
         // Use fov from aladin
-        fov    <- useState(none[Fov])
+        fov        <- useState(none[Fov])
         // Survey
-        survey <- useState(
-                    props.vizConf
-                      .flatMap(_.centralWavelength)
-                      .map(w => surveyForWavelength(w.value))
-                      .getOrElse(ImageSurvey.DSS)
-                  )
+        survey     <- useState(
+                        props.vizConf
+                          .flatMap(_.centralWavelength)
+                          .map(w => surveyForWavelength(w.value))
+                          .getOrElse(ImageSurvey.DSS)
+                      )
         // Update survey if conf changes
-        _      <-
+        _          <-
           useEffectWithDeps(props.vizConf.flatMap(_.centralWavelength.map(_.value))): w =>
             w.map(w => survey.setState(surveyForWavelength(w))).getOrEmpty
       } yield {
@@ -306,7 +307,7 @@ object AladinContainer extends AladinCommon {
          */
         def onPositionChanged(u: PositionChanged): Callback = {
           val viewCoords = Coordinates(u.ra, u.dec)
-          val viewOffset = baseCoordinates.value.diff(viewCoords).offset
+          val viewOffset = baseCoordinates.diff(viewCoords).offset
           currentPos.setState(Some(viewCoords)) *>
             props.updateViewOffset(viewOffset)
         }
@@ -334,14 +335,14 @@ object AladinContainer extends AladinCommon {
         val baseCoordinatesForAladin: String =
           currentPos.value
             .map(Coordinates.fromHmsDms.reverseGet)
-            .getOrElse(Coordinates.fromHmsDms.reverseGet(baseCoordinates.value))
+            .getOrElse(Coordinates.fromHmsDms.reverseGet(baseCoordinates))
 
         val basePosition =
           List(
-            SVGTarget.CrosshairTarget(baseCoordinates.value, Css.Empty, 10),
-            SVGTarget.CircleTarget(baseCoordinates.value, ExploreStyles.BaseTarget, 3),
+            SVGTarget.CrosshairTarget(baseCoordinates, Css.Empty, 10),
+            SVGTarget.CircleTarget(baseCoordinates, ExploreStyles.BaseTarget, 3),
             SVGTarget.LineTo(
-              baseCoordinates.value,
+              baseCoordinates,
               props.asterismTracking.baseCoordinates,
               ExploreStyles.PMCorrectionLine
             )
@@ -376,7 +377,7 @@ object AladinContainer extends AladinCommon {
             for {
               idx <- refineV[NonNegative](i).toOption
               gs  <- props.selectedGuideStar
-              c   <- baseCoordinates.value.offsetBy(gs.posAngle, o) if visible
+              c   <- baseCoordinates.offsetBy(gs.posAngle, o) if visible
             } yield SVGTarget.OffsetIndicator(c, idx, o, oType, css, 4)
           }
 
@@ -401,7 +402,7 @@ object AladinContainer extends AladinCommon {
           (acquisitionOffsetIndicators |+| scienceOffsetIndicators).flattenOption
 
         val screenOffset =
-          currentPos.value.map(_.diff(baseCoordinates.value).offset).getOrElse(Offset.Zero)
+          currentPos.value.map(_.diff(baseCoordinates).offset).getOrElse(Offset.Zero)
 
         // Use explicit reusability that excludes target changes
         given Reusability[AladinOptions] = reusability.withoutTarget
@@ -423,7 +424,7 @@ object AladinContainer extends AladinCommon {
                     _,
                     _,
                     screenOffset,
-                    baseCoordinates.value,
+                    baseCoordinates,
                     // Order matters
                     candidates ++ basePosition ++ sciencePositions ++ offsetTargets
                   )
diff --git a/explore/common/src/main/scala/explore/model/reusability.scala b/explore/common/src/main/scala/explore/model/reusability.scala
index a1eefdc072..90a7692b52 100644
--- a/explore/common/src/main/scala/explore/model/reusability.scala
+++ b/explore/common/src/main/scala/explore/model/reusability.scala
@@ -41,9 +41,9 @@ import lucuma.core.math.WavelengthDither
 import lucuma.core.model.Configuration
 import lucuma.core.model.ConfigurationRequest
 import lucuma.core.model.ExposureTimeMode
-import lucuma.core.model.ObjectTracking
 import lucuma.core.model.PosAngleConstraint
 import lucuma.core.model.TimingWindow
+import lucuma.core.model.Tracking
 import lucuma.core.model.sequence.Atom
 import lucuma.itc.ItcCcd
 import lucuma.itc.client.GraphResult
@@ -121,7 +121,7 @@ object reusability:
   given Reusability[ItcInstrumentConfig]                = Reusability.byEq
   given Reusability[ConfigSelection]                    = Reusability.byEq
   given Reusability[CentralWavelength]                  = Reusability.byEq
-  given Reusability[ObjectTracking]                     = Reusability.byEq
+  given Reusability[Tracking]                           = Reusability.byEq
   given Reusability[Asterism]                           = Reusability.byEq[Asterism]
   given Reusability[TargetWithOptId]                    = Reusability.byEq
   given Reusability[GlobalPreferences]                  = Reusability.byEq
diff --git a/explore/model-tests/shared/src/test/scala/explore/model/boopickle/BoopickleSuite.scala b/explore/model-tests/shared/src/test/scala/explore/model/boopickle/BoopickleSuite.scala
index 9b5b17e798..230ed59abb 100644
--- a/explore/model-tests/shared/src/test/scala/explore/model/boopickle/BoopickleSuite.scala
+++ b/explore/model-tests/shared/src/test/scala/explore/model/boopickle/BoopickleSuite.scala
@@ -23,11 +23,11 @@ import lucuma.core.math.arb.ArbRightAscension.given
 import lucuma.core.math.arb.ArbWavelength.given
 import lucuma.core.model.ConstraintSet
 import lucuma.core.model.ElevationRange
-import lucuma.core.model.SiderealTracking
+import lucuma.core.model.Tracking
 import lucuma.core.model.UnnormalizedSED
 import lucuma.core.model.arb.ArbConstraintSet.given
 import lucuma.core.model.arb.ArbElevationRange.given
-import lucuma.core.model.arb.ArbSiderealTracking.given
+import lucuma.core.model.arb.ArbTracking.given
 import lucuma.core.model.arb.ArbUnnormalizedSED.given
 
 class BoopickleSuite
@@ -46,7 +46,7 @@ class BoopickleSuite
   checkAll("Pickler[ProperMotion]", PicklerTests[ProperMotion].pickler)
   checkAll("Pickler[RadialVelocity]", PicklerTests[RadialVelocity].pickler)
   checkAll("Pickler[Parallax]", PicklerTests[Parallax].pickler)
-  checkAll("Pickler[SiderealTracking]", PicklerTests[SiderealTracking].pickler)
+  checkAll("Pickler[Tracking]", PicklerTests[Tracking].pickler)
   checkAll("Pickler[GuideStarCandidate]", PicklerTests[GuideStarCandidate].pickler)
   checkAll("Pickler[ElevationRange]", PicklerTests[ElevationRange].pickler)
   checkAll("Pickler[ConstraintSet]", PicklerTests[ConstraintSet].pickler)
diff --git a/explore/model/shared/src/main/scala/explore/events/CatalogMessage.scala b/explore/model/shared/src/main/scala/explore/events/CatalogMessage.scala
index e59396f69b..035eda60db 100644
--- a/explore/model/shared/src/main/scala/explore/events/CatalogMessage.scala
+++ b/explore/model/shared/src/main/scala/explore/events/CatalogMessage.scala
@@ -8,7 +8,7 @@ import boopickle.Pickler
 import explore.model.boopickle.CatalogPicklers
 import lucuma.ags.GuideStarCandidate
 import lucuma.core.enums.ObservingModeType
-import lucuma.core.model.ObjectTracking
+import lucuma.core.model.Tracking
 import workers.WorkerRequest
 
 import java.time.Duration
@@ -21,7 +21,7 @@ object CatalogMessage extends CatalogPicklers {
   }
 
   case class GSRequest(
-    tracking:    ObjectTracking,
+    tracking:    Tracking,
     vizTime:     Instant,
     obsModeType: ObservingModeType
   ) extends Request {
diff --git a/explore/model/shared/src/main/scala/explore/model/Asterism.scala b/explore/model/shared/src/main/scala/explore/model/Asterism.scala
index d6a1170475..567fcbecce 100644
--- a/explore/model/shared/src/main/scala/explore/model/Asterism.scala
+++ b/explore/model/shared/src/main/scala/explore/model/Asterism.scala
@@ -9,9 +9,9 @@ import cats.derived.*
 import cats.syntax.all.*
 import explore.model.extensions.*
 import lucuma.core.data.Zipper
-import lucuma.core.model.ObjectTracking
 import lucuma.core.model.SiderealTracking
 import lucuma.core.model.Target
+import lucuma.core.model.Tracking
 import lucuma.schemas.model.*
 import monocle.*
 
@@ -52,8 +52,8 @@ case class Asterism(private val targets: Zipper[TargetWithId]) derives Eq {
   def focusOn(tid: Target.Id): Asterism =
     targets.findFocus(_.id === tid).map(Asterism.apply).getOrElse(this)
 
-  def baseTracking: Option[ObjectTracking] =
-    ObjectTracking.fromAsterism(targets.toNel.map(_.target))
+  def baseTracking: Option[Tracking] =
+    Tracking.fromAsterism(targets.toNel.map(_.target))
 
   def hasId(id: Target.Id): Boolean = targets.exists(_.id === id)
 }
diff --git a/explore/model/shared/src/main/scala/explore/model/Observation.scala b/explore/model/shared/src/main/scala/explore/model/Observation.scala
index d6c7b17b59..924a6b1b73 100644
--- a/explore/model/shared/src/main/scala/explore/model/Observation.scala
+++ b/explore/model/shared/src/main/scala/explore/model/Observation.scala
@@ -31,7 +31,6 @@ import lucuma.core.model.Attachment
 import lucuma.core.model.Configuration
 import lucuma.core.model.ConfigurationRequest
 import lucuma.core.model.ConstraintSet
-import lucuma.core.model.ObjectTracking
 import lucuma.core.model.ObservationReference
 import lucuma.core.model.ObservationValidation
 import lucuma.core.model.ObservationWorkflow
@@ -39,6 +38,7 @@ import lucuma.core.model.PosAngleConstraint
 import lucuma.core.model.SourceProfile
 import lucuma.core.model.Target
 import lucuma.core.model.TimingWindow
+import lucuma.core.model.Tracking
 import lucuma.core.model.sequence.ExecutionDigest
 import lucuma.core.model.sequence.gmos.GmosCcdMode
 import lucuma.core.optics.syntax.lens.*
@@ -288,13 +288,13 @@ case class Observation(
     if (newConfigurationRequestApplies(request.configuration)) updateToPending(request.id)
     else this
 
-  def asterismTracking(allTargets: TargetList): Option[ObjectTracking] =
+  def asterismTracking(allTargets: TargetList): Option[Tracking] =
     NonEmptyList
       .fromList:
         scienceTargetIds.toList
           .map(id => allTargets.get(id).map(_.target))
           .flattenOption
-      .flatMap(ObjectTracking.fromAsterism(_))
+      .flatMap(Tracking.fromAsterism(_))
 
   def hasTargetOfOpportunity(allTargets: TargetList): Boolean =
     scienceTargetIds.toList
diff --git a/explore/model/shared/src/main/scala/explore/model/boopickle/CatalogPickler.scala b/explore/model/shared/src/main/scala/explore/model/boopickle/CatalogPickler.scala
index e56b33aacf..abae9e5932 100644
--- a/explore/model/shared/src/main/scala/explore/model/boopickle/CatalogPickler.scala
+++ b/explore/model/shared/src/main/scala/explore/model/boopickle/CatalogPickler.scala
@@ -18,9 +18,16 @@ import lucuma.core.math.Coordinates
 import lucuma.core.math.Epoch
 import lucuma.core.math.Parallax
 import lucuma.core.math.ProperMotion
-import lucuma.core.model.ObjectTracking
+import lucuma.core.model.CompositeTracking
+import lucuma.core.model.ConstantTracking
+import lucuma.core.model.EphemerisCoordinates
+import lucuma.core.model.EphemerisTracking
 import lucuma.core.model.SiderealTracking
+import lucuma.core.model.Tracking
 import lucuma.core.model.sequence.flamingos2.Flamingos2FpuMask
+import lucuma.core.util.Timestamp
+
+import scala.collection.immutable.TreeMap
 
 // Boopicklers for catalog related types
 trait CatalogPicklers extends CommonPicklers:
@@ -58,8 +65,6 @@ trait CatalogPicklers extends CommonPicklers:
   given Pickler[Parallax] =
     transformPickler(Parallax.fromMicroarcseconds)(_.μas.value.value)
 
-  given Pickler[SiderealTracking] = generatePickler
-
   given Pickler[GuideStarCandidate] = generatePickler
 
   given Pickler[AgsPosition] = generatePickler
@@ -91,16 +96,30 @@ trait CatalogPicklers extends CommonPicklers:
 
   given Pickler[AgsAnalysis.Usable] = generatePickler
 
-  given Pickler[ObjectTracking.SiderealObjectTracking] = generatePickler
+  given Pickler[SiderealTracking] = generatePickler
+
+  given Pickler[CompositeTracking] = generatePickler
 
-  given Pickler[ObjectTracking.SiderealAsterismTracking] = generatePickler
+  given Pickler[ConstantTracking] = generatePickler
 
-  given Pickler[ObjectTracking.ConstantTracking] = generatePickler
+  given Pickler[EphemerisCoordinates] = generatePickler
+
+  given [K: Pickler: Ordering, V: Pickler]: Pickler[TreeMap[K, V]] =
+    transformPickler((m: Map[K, V]) => TreeMap.empty[K, V] ++ m)(_.toMap)
+
+  import _root_.cats.Order.given
+  // summon[Ordering[lucuma.core.util.Timestamp]]
+
+  given Pickler[EphemerisTracking] =
+    transformPickler((m: TreeMap[Timestamp, EphemerisCoordinates]) => EphemerisTracking(m.toSeq*))(
+      _.toMap
+    )
 
-  given Pickler[ObjectTracking] =
-    compositePickler[ObjectTracking]
-      .addConcreteType[ObjectTracking.SiderealObjectTracking]
-      .addConcreteType[ObjectTracking.SiderealAsterismTracking]
-      .addConcreteType[ObjectTracking.ConstantTracking]
+  given Pickler[Tracking] =
+    compositePickler[Tracking]
+      .addConcreteType[SiderealTracking]
+      .addConcreteType[CompositeTracking]
+      .addConcreteType[ConstantTracking]
+      .addConcreteType[EphemerisTracking]
 
 object CatalogPicklers extends CatalogPicklers
diff --git a/explore/model/shared/src/main/scala/explore/model/boopickle/CommonPicklers.scala b/explore/model/shared/src/main/scala/explore/model/boopickle/CommonPicklers.scala
index 021d011f09..010fb5d8dc 100644
--- a/explore/model/shared/src/main/scala/explore/model/boopickle/CommonPicklers.scala
+++ b/explore/model/shared/src/main/scala/explore/model/boopickle/CommonPicklers.scala
@@ -35,6 +35,7 @@ import lucuma.core.model.Target
 import lucuma.core.util.Enumerated
 import lucuma.core.util.NewType
 import lucuma.core.util.TimeSpan
+import lucuma.core.util.Timestamp
 import lucuma.schemas.model.CentralWavelength
 import org.http4s.Uri
 
@@ -204,6 +205,8 @@ trait CommonPicklers {
       SignalToNoise.FromBigDecimalExact.getOption(v).getOrElse(sys.error("Cannot unpickle"))
     )(_.toBigDecimal)
 
+  given Pickler[Timestamp] =
+    transformPickler((instant: Instant) => Timestamp.fromInstant(instant).get)(_.toInstant)
 }
 
 object CommonPicklers extends CommonPicklers
diff --git a/explore/model/shared/src/main/scala/explore/model/boopickle/ItcPickler.scala b/explore/model/shared/src/main/scala/explore/model/boopickle/ItcPickler.scala
index ed1aee89a2..5343e41185 100644
--- a/explore/model/shared/src/main/scala/explore/model/boopickle/ItcPickler.scala
+++ b/explore/model/shared/src/main/scala/explore/model/boopickle/ItcPickler.scala
@@ -41,7 +41,6 @@ import lucuma.core.model.UnnormalizedSED
 import lucuma.core.model.sequence.gmos.GmosCcdMode
 import lucuma.core.util.Gid
 import lucuma.core.util.Of
-import lucuma.core.util.Timestamp
 import lucuma.itc.Error
 import lucuma.itc.IntegrationTime
 import lucuma.itc.ItcAxis
@@ -113,10 +112,6 @@ trait ItcPicklers extends CommonPicklers {
 
   given Pickler[ModeAO] = picklerNewType(ModeAO)
 
-  import java.time.Instant
-  given Pickler[Timestamp] =
-    transformPickler((instant: Instant) => Timestamp.fromInstant(instant).get)(_.toInstant)
-
   given [A: Gid]: Pickler[A] =
     transformPickler((str: String) => Gid[A].fromString.getOption(str).get)(_.toString)
 
diff --git a/explore/model/shared/src/main/scala/explore/model/extensions.scala b/explore/model/shared/src/main/scala/explore/model/extensions.scala
index 2d8961dbc9..25def7f688 100644
--- a/explore/model/shared/src/main/scala/explore/model/extensions.scala
+++ b/explore/model/shared/src/main/scala/explore/model/extensions.scala
@@ -13,9 +13,11 @@ import lucuma.core.math.Declination
 import lucuma.core.math.Epoch
 import lucuma.core.math.Region
 import lucuma.core.math.RightAscension
-import lucuma.core.model.ObjectTracking
+import lucuma.core.model.CompositeTracking
+import lucuma.core.model.ConstantTracking
 import lucuma.core.model.SiderealTracking
 import lucuma.core.model.Target
+import lucuma.core.model.Tracking
 import lucuma.schemas.model.SiderealTargetWithId
 import lucuma.schemas.model.TargetWithId
 
@@ -59,8 +61,8 @@ object extensions:
       TargetWithId.target.replace(targetWithId.target.at(i))(targetWithId)
 
   extension (targets: NonEmptyList[TargetWithId])
-    def baseTracking: Option[ObjectTracking] =
-      ObjectTracking.fromAsterism(targets.map(_.target))
+    def baseTracking: Option[Tracking] =
+      Tracking.fromAsterism(targets.map(_.target))
 
     def toSidereal: List[SiderealTargetWithId] =
       targets.toList.map(_.toSidereal).flattenOption
@@ -69,11 +71,11 @@ object extensions:
     // ToO as a ToO and returns the region of the first ToO it finds. Since we "shouldn't"
     // have asterisms with multiple ToOs, this is probably fine.
     def coordsOrRegionAt(vizTime: Option[Instant]): Option[Either[Coordinates, Region]] =
-      ObjectTracking
+      Tracking
         .orRegionFromAsterism(targets.map(_.target)) match
-        case Left(ot)      =>
-          vizTime.fold(ot.baseCoordinates.asLeft.some)(v => ot.at(v).map(_.value.asLeft))
-        case Right(region) => region.asRight.some
+        case Left(tracking) =>
+          vizTime.fold(tracking.baseCoordinates.asLeft.some)(v => tracking.at(v).map(_.asLeft))
+        case Right(region)  => region.asRight.some
 
     def isMixed: Boolean =
       targets
@@ -115,3 +117,10 @@ object extensions:
       case None                               => ""
       case Some(Left(dec))                    => f(dec)
       case Some(Right(arc: Arc[Declination])) => arc.format(f)
+
+  extension (tracking: Tracking)
+    def baseCoordinates: Coordinates = tracking match
+      case SiderealTracking(baseCoordinates, _, _, _, _) => baseCoordinates
+      case ConstantTracking(coordinates)                 => coordinates
+      case CompositeTracking(nel)                        => Coordinates.centerOf(nel.map(_.baseCoordinates))
+      case _                                             => sys.error("Non sidereals are not supported")
diff --git a/explore/workers/src/main/scala/workers/AgsServer.scala b/explore/workers/src/main/scala/workers/AgsServer.scala
index e168b504ca..e7c320dd32 100644
--- a/explore/workers/src/main/scala/workers/AgsServer.scala
+++ b/explore/workers/src/main/scala/workers/AgsServer.scala
@@ -23,7 +23,7 @@ object AgsServer extends WorkerServer[IO, AgsMessage.Request] {
   @JSExport
   def runWorker(): Unit = run.unsafeRunAndForget()
 
-  private val AgsCacheVersion: Int = 18
+  private val AgsCacheVersion: Int = 19
 
   private val CacheRetention: Duration = Duration.ofDays(60)
 
diff --git a/explore/workers/src/main/scala/workers/CatalogCache.scala b/explore/workers/src/main/scala/workers/CatalogCache.scala
index 06cacb0aac..e60a09f7df 100644
--- a/explore/workers/src/main/scala/workers/CatalogCache.scala
+++ b/explore/workers/src/main/scala/workers/CatalogCache.scala
@@ -26,7 +26,7 @@ import java.time.temporal.ChronoUnit
 
 trait CatalogQuerySettings {
   private val MaxTargets: Int   = 100
-  private val CacheVersion: Int = 3
+  private val CacheVersion: Int = 4
 
   protected given Hash[Coordinates] = Hash.fromUniversalHashCode
   protected given ADQLInterpreter   = ADQLInterpreter.nTarget(MaxTargets)
@@ -66,7 +66,7 @@ trait CatalogCache extends CatalogIDB {
         // Make a query based on two coordinates of the base of an asterism over a year
         val query: CoordinatesRangeQueryByADQL =
           CoordinatesRangeQueryByADQL(
-            NonEmptyList.of(a.value, b.value),
+            NonEmptyList.of(a, b),
             candidatesArea,
             brightnessConstraints.some
           )
diff --git a/project/Versions.scala b/project/Versions.scala
index 01df72eeb2..1d367b7faa 100644
--- a/project/Versions.scala
+++ b/project/Versions.scala
@@ -35,7 +35,7 @@ object Versions {
   val log4s                  = "1.10.0"
   val logback                = "1.5.20"
   val lucumaBC               = "0.4.0"
-  val lucumaCore             = "0.147.2"
+  val lucumaCore             = "0.149.0"
   val lucumaPrimeStyles      = "0.5.0"
   val lucumaReact            = "0.85.3"
   val lucumaServers          = "0.51.1"