diff --git a/lightcurve/static/lightcurve/js/lightcurve.js b/lightcurve/static/lightcurve/js/lightcurve.js
index 833f510..657efa5 100644
--- a/lightcurve/static/lightcurve/js/lightcurve.js
+++ b/lightcurve/static/lightcurve/js/lightcurve.js
@@ -237,6 +237,9 @@ function setupImagePairs() {
 
     data.pairs = JSON.stringify(pairs);
 
+    // Manual color index
+    data.manual_color_index = $('#set-manual-ci').val();
+
     // TODO(ian): POST it all to some endpoint.
     $.post('/lightcurve/' + window.lightcurveId + '/save_image_pairs', data, function(result) {
       if (result.success) {
diff --git a/lightcurve/templates/partials/image_pair_selector.html b/lightcurve/templates/partials/image_pair_selector.html
index 999ab8d..b51b426 100644
--- a/lightcurve/templates/partials/image_pair_selector.html
+++ b/lightcurve/templates/partials/image_pair_selector.html
@@ -1,12 +1,19 @@
 <div class="color-index-selector">
-  <form class="form form-inline">
-    <label for="select-color-index">Color index</label>
-    <select id="select-color-index" class="form-control js-select-color-index" style="width: 10em">
-      <option value="NONE">None</option>
-      {% for band in ci_bands %}
-        <option value="{{band}}" {% if lightcurve.ciband == band %}selected{% endif %}>{{band}}</option>
-      {% endfor %}
-    </select>
+  <form class="form">
+    <div class="form-group">
+      <label for="set-manual-ci">Manual color index</label>
+      - this value overrides the computed color index from image pairs.
+      <input id="set-manual-ci" class="form-control" style="width: 20em" type="number" step="any" value="{{reduction.color_index_manual}}">
+    </div>
+    <div class="form-group">
+      <label for="select-color-index">Color index</label>
+      <select id="select-color-index" class="form-control js-select-color-index" style="width: 10em">
+        <option value="NONE">None</option>
+        {% for band in ci_bands %}
+          <option value="{{band}}" {% if lightcurve.ciband == band %}selected{% endif %}>{{band}}</option>
+        {% endfor %}
+      </select>
+    </div>
   </form>
 </div>
 <div class="image-pair-selector" style="margin-top:1em">
diff --git a/lightcurve/views.py b/lightcurve/views.py
index cf9f2bf..0a3c9b7 100644
--- a/lightcurve/views.py
+++ b/lightcurve/views.py
@@ -163,8 +163,15 @@ def apply_photometry_settings(request, lightcurve_id):
 
 def save_image_pairs(request, lightcurve_id):
     lc = get_object_or_404(LightCurve, id=lightcurve_id, user=request.user.id)
-    images = lc.imageanalysis_set.all()
+    reduction = lc.get_or_create_reduction()
+    color_index_manual = request.POST.get('manual_color_index')
+    if color_index_manual:
+        reduction.color_index_manual = float(color_index_manual)
+    else:
+        reduction.color_index_manual = None
+    reduction.save()
 
+    images = lc.imageanalysis_set.all()
     ciband = request.POST.get('ciband')
     pairs = json.loads(request.POST.get('pairs'))