diff --git a/src/Vela.jl b/src/Vela.jl
index 644b1672..7e08fbf6 100644
--- a/src/Vela.jl
+++ b/src/Vela.jl
@@ -17,6 +17,7 @@ export GQ
 include("toa/ephemeris.jl")
 include("toa/toa.jl")
 include("toa/wideband_toa.jl")
+include("toa/photon.jl")
 include("parameter/parameter.jl")
 include("model/component.jl")
 include("model/kernel.jl")
@@ -48,6 +49,7 @@ include("model/dispersion_measurement_noise.jl")
 include("model/marginalized_timing_model.jl")
 include("model/timing_model.jl")
 include("model/wideband_model.jl")
+include("model/photon_model.jl")
 include("prior/prior.jl")
 include("prior/prior_scaling.jl")
 include("prior/simple_prior.jl")
diff --git a/src/model/photon_model.jl b/src/model/photon_model.jl
new file mode 100644
index 00000000..9bbac7d2
--- /dev/null
+++ b/src/model/photon_model.jl
@@ -0,0 +1,14 @@
+"""Update a `CorrectedWidebandTOA` object. 
+Most components only affect the TOA part and not the DM part."""
+correct_toa(
+    component::Component,
+    photon::Photon,
+    photcorr::PhotonCorrection,
+    params::NamedTuple,
+) = PhotonCorrection(
+    correct_toa(component, photon.toa, photcorr.arrival_time_correction, params),
+)
+
+"""Update a `WidebandTOA` object using a timing model."""
+correct_toa(model::TimingModel, wtoa::Photon, params::NamedTuple) =
+    correct_toa(model, wtoa, PhotonCorrection(), params)
diff --git a/src/toa/photon.jl b/src/toa/photon.jl
new file mode 100644
index 00000000..74ea207f
--- /dev/null
+++ b/src/toa/photon.jl
@@ -0,0 +1,37 @@
+export Photon
+
+struct Photon <: TOABase
+    arrival_time::TOA
+    weight::GQ{0,Float64}
+
+    function Photon(arrival_time, frequency, weight, ephem, index)
+        toa = TOA(arrival_time, time(0.0), frequency, dimensionless(0.0), ephem, index)
+        return new(toa, weight)
+    end
+end
+
+struct PhotonCorrection <: TOACorrectionBase
+    arrival_time_correction::TOACorrection
+end
+
+function PhotonCorrection(delay, phase, ssb_psr_pos)
+    @assert all(iszero.(ssb_psr_pos)) || dot(ssb_psr_pos, ssb_psr_pos) ≈ dimensionless(1.0) "ssb_psr_pos must be a zero vector (representing pending computation) or a unit vector."
+
+    return PhotonCorrection(
+        TOACorrection(
+            delay,
+            phase,
+            dimensionless(1.0),
+            GQ{2}(0.0),
+            frequency(0.0),
+            dimensionless(1.1),
+            ssb_psr_pos,
+        ),
+    )
+end
+
+PhotonCorrection() =
+    PhotonCorrection(time(0.0), dimensionless(0.0), dimensionless.((0.0, 0.0, 0.0)))
+
+fractional_phase(photcorr::PhotonCorrection) =
+    photcorr.arrival_time_correction.phase - round(photcorr.arrival_time_correction.phase)