The iSPEX-app

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In order to measure aerosols with your smartphone, you will need the iSPEX add-on, together with the app. The iPhone app is freely distributed via the App-store. To get the app click here to go to the App-store. The link only works if you use your iPhone!

In principle, the app only has to perform a few simple tasks:

  • it allows you to make a picture/movie of the modulated spectrum;
  • it adds to this the geographical location of the measurement, and the direction in which you pointed your iSPEX (why?);
  • This information will be sent to a central database.

In the central database, your measurement will be compared with those of thousends of other iSPEX users. This allows us to increase the accuracy of the final results.

The app translated

Currently, the iSPEX app is only available in Dutch. To allow non-Dutch speaking iSPEX enthousiasts to use the app, we have translated the most important messages of the app below.

Tab 1: Aerosols

Start screen:

This is the first screen of the iSPEX app

This is the first screen you will see once you’ve opened the app. The message on the top of the screen says:

Aerosols, Place the iSPEX add-on. Turn on your sound. Stand with the sun in your back and push “Begin meting!”(start measurement).

The two buttons say:

  • Start measurement!
  • Watch instruction video

The tabs on the bottom of the screen show the different functions of the app. From left to right:

  • Aerosols (the one you are in now)
  • Map
  • Spectrum
  • Polarisation
  • Info

The next screen after you push “begin meting!”

Step 1

If you push the button “begin meting!”, you will see the following screen, which asks you to do the following:

Step 1, Keep your iPhone vertical. Follow the arrow, until the button ‘Ok, verder’ appears.

The button in the top-left corner (Annuleren) allows you to cancel the process.

You’ve pointed in the right direction. Push “Ok, verder” to start the measurement.

Push “Begin meting”

Step 2

After you have pushed “Ok, verder” (Ok, continue), you’ll see the following screen, with an arrow pointing up, unless you’ve not turned on your GPS (see below). The text says:

Keep the iPhone in front of you (vertical). Push “Begin meting” (start measurement).

If you haven’t placed your iSPEX add on, or you are not outside pointing at the blue sky, the app will give an error message shown below.

Let’s assume that this is not the case. Then, you have just started your measurement!

You’ve just started your measurement! Move your iPhone up with a straight arm.


Although it still says step 2 in the header, youve just started measuring!

This screen tels you:

Keep your arm straight as you move (your iPhone) slowly to the point above your head.

When you reach this highest point, the iPhone will be in a horizontal position. At this point, the app asks you to repeat this measurement (just to be sure).

Please repeat the measurement by pressing “Meet nog een keer”


To make sure that we are looking at the same patch of blue sky, we ask you to repeat the measurement:

Push on the button to measure once more

If the two measurements are too different from eachother, the app asks you to measure one more time. Most of the time, this is not necessary.

You’ve finished your measurements. Press “Naar resultaat” to see the results

Measurement complete

The two measurements are similar enough to be a good measurement. This means that you have completed this measurement. The app now tells you:

Done! Press the button to continue

If you press the button: “Naar resultaat” (To results), you will see a preliminary interpretation of your measurement.

Please submit the results by pressing “Verstuur”


This page of the app tells you the preliminary results (Voorlopig resultaat) of your measurement. For a definite interpretation, we ask you to submit (Verstuur) the measurements to iSPEX headquarters.

The colored balloon indicates how clear the sky was during the measurement, which is also described by the text next to it, in this case “Heel helder” (very clear).

Please write your first and last name in the boxes. Your first name will be shown for 24 hours on the iSPEX measurement map.

If you want to share the results of your measurement, press “Deel” (share) to write a tweet. This should be done before you submit your result, since you don’t get the chance afterwards.

Please confirm (OK) or cancel (annuleren) the submission of your measurement. Make sure that you have an internet connection when you submit!


A pop-up asks you to confirm the submission of your measurement:

Confirm: Send *** kB to iSPEX headquarters? When you are not connected to the internet, it will be submitted later

The automatic submission of the data, once you have a good connection, does not work yet! Please make sure your connection is good at this point in order not to lose the data

The buttons:

  • Cancel
  • Ok

The app will now take a while to send the data (in this case 672 kB) to iSPEX HQ. Once this has succesfully been sent, you will be redirected to the next tab of the app: the Map with your datapoint on it.

Congratulations! You’ve just succesfully submitted an aerosol measurement. Thank you for your participation!

Tab 2: The Map

The translation of this tab will soon follow

Tab 3: Spectrum

The translation of this tab will soon follow

Tab 4: Polarisation

The translation of this tab will soon follow

Tab 5: Info

The translation of this tab will soon follow