diff --git a/js/app.js b/js/app.js
index 36f8adc..33eefb5 100644
--- a/js/app.js
+++ b/js/app.js
@@ -670,7 +670,7 @@ $(window).ready(function() {
             if(currentPosition && currentPosition.marker) map.addLayer(currentPosition.marker);
         // turning the switch on
         } else {
-            if(callsign.length == null || callsign.length < 5) { alert('Please enter a valid callsign, at least 5 characters'); return; }
+            if(callsign.length == null || callsign.length < 3) { alert('Please enter a valid callsign, at least 3 characters'); return; }
             if(!callsign.match(/^[a-zA-Z0-9\_\-]+$/)) { alert('Invalid characters in callsign (use only a-z,0-9,-,_)'); return; }
 
             field.attr('disabled','disabled');
diff --git a/js/tracker.js b/js/tracker.js
index 8ea4a74..1045406 100644
--- a/js/tracker.js
+++ b/js/tracker.js
@@ -718,8 +718,8 @@ function launchSitePredictions(times, station, properties, marker) {
     var completed = 0;
     for (var i = 0; i < dates.length; i++) {
         var lon = ((360 + (position[1] % 360)) % 360)
-        var url = "https://predict.cusf.co.uk/api/v1/?launch_latitude=" + position[0] + "&launch_longitude=" + lon + "&launch_datetime=" + dates[i] + "&ascent_rate=" + properties[0] + "&burst_altitude=" + properties[2] + "&descent_rate=" + properties[1];
-        //var url = "https://api.v2.sondehub.org/tawhiri?launch_latitude=" + position[0] + "&launch_longitude=" + lon + "&launch_datetime=" + dates[i] + "&ascent_rate=" + properties[0] + "&burst_altitude=" + properties[2] + "&descent_rate=" + properties[1];
+        //var url = "https://predict.cusf.co.uk/api/v1/?launch_latitude=" + position[0] + "&launch_longitude=" + lon + "&launch_datetime=" + dates[i] + "&ascent_rate=" + properties[0] + "&burst_altitude=" + properties[2] + "&descent_rate=" + properties[1];
+        var url = "https://api.v2.sondehub.org/tawhiri?launch_latitude=" + position[0] + "&launch_longitude=" + lon + "&launch_datetime=" + dates[i] + "&ascent_rate=" + properties[0] + "&burst_altitude=" + properties[2] + "&descent_rate=" + properties[1];
         showPrediction(url).done(handleData).fail(handleError);
     }
     function handleData(data) {