Tutorial to become a Planetary Guardian 

First time observing a Near-Earth Object? Read this page to master your Unistellar telescope and join our team of Planetary Guardians.


1. Select your mission

The passage of a near-Earth object is a rare event to record. To begin guarding the planet, you first need to select a mission suitable for your observing location. Go to our Planetary Defense Campaign Page and select a near-Earth asteroid you want to observe. Your ability to participate in the scientific mission may depend on which hemisphere you are observing from!

2. Check the Object Coordinates

Near-Earth objects are fast moving targets to observe. Their coordinates in the sky depend on the location and date of the observation. If the near-Earth object is in the Unistellar App Catalog, then you will have access to the coordinates from the catalog. However, if the near-Earth object is not in the Unistellar App Catalog, you have to compute its celestial coordinates with our Moving Target Ephemerides page. The recording parameters, Record duration, Exposure Time and Gain, are always given on the Planetary Defense Campaign Page.

3. Moving Target Ephemerides (optional)

If you want to observe a near-Earth object that is not in the Unistellar App Catalog, visit our Moving Target Ephemerides page. In the Ephemeris Parameters section, select your target and enter the location where you’ll be observing, as well as the date and local time when you’ll be observing.  Click on Generate to get your results. After a few seconds, the Ephemeris Results section will be generated with a list of celestial coordinates for your night. Each line corresponds to the position of your target at a specific time. If your target is visible from your location, you will be able to click on the smartphone icon (Deep Link) that will open your Unistellar App and fill the Planetary Defense section with the proper fields. If your target is not visible, a crossed-out eye icon will appear. You need to save these coordinates for your observation or you will have to compute them during your observation.


Once your Unistellar telescope is set to observe the night sky, you can use the scientific mode of the Unistellar App. 

1. 10 minutes before 

It is time to point to your target. You have two options depending on whether or not the near-earth object is in the App Catalog.

    A. The asteroid is in the App Catalog: Open your Unistellar App, in the Catalog, enter the name of your asteroid, select it and click on Goto. Once the goto is Done,  click on the Science menu and select the Defense tab. Skip the step that prompts you to Point to the target. Enter the Record duration, Exposure time, and Gain and click on Save.

    B. The asteroid is NOT in the App Catalog: The quickest way to find your target is to use your smartphone to click on the Deep Link generated with our Moving Target Ephemeris tool that you read about in the previous section. It will automatically open the Defense tab of your Unistellar App to enter the coordinates of the target and its recording parameters. If the Right ascension and Declination box are filled with the correct coordinates, click on Goto to point to your target. Once Goto is done, if the Record duration, Exposure time, and Gain are correct, you can click on Save.

2. Launch observation

When you are ready, click on the Record button to start the observation. You can begin recording at any point of the night when the target is visible to you and will remain so for around two hours. 

During the observation, you may see the near-Earth object moving in the live view. 

3. Complete observation

Once the recording is over, click on Continue to calibrate your sensor. This calibration step gathers Dark Frames, which will help us better analyze your observation. You must put the dust cap on your telescope before recording the calibration.

After this step, a final message appears: “Recording complete”. The mission is over.


1. Share your data

Once you are at home, please upload your data to our server. Our team of scientists will analyze your observation to check if you detected the near-Earth object. If you need help, please read these guidelines on “how to upload my data”.

2. Tell Unistellar you participated

To make sure your contribution is properly processed and you are credited for the result, always fill out this Planetary Defense Observation Report. It asks for your name, the serial number of your telescope, and the name of the scientific mission you just accomplished. 

We will send you the result of your scientific mission through our Slack communication platform within 24 hours.

Great Work, Citizen Astronomer.