How to Observe Asteroid Apophis with your eVscope

Credit: Ron Miller

Want to learn more about infamous asteroid Apophis? Check out our detailed blog post about this potentially hazardous asteroid.

Where and when to observe Apophis with your eVscope

1. First, visit our Asteroid Occultations: Predictions page.
   a. In the drop-down menu, select North America.
   b. Scroll down to 99942 Apophis and click on it.
2. A map of the United States with the path of the occultation should appear below. Zoom into the map so you can see the exact location where you can observe this occultation.a. If you are near a white dot, check the passage time it indicates. This will tell you at which exact time the occultation will happen. If you are between two white dots, use the passage time from the dot located on the right.
   b. Be careful: these times are in UTC, so you will need to convert them to your local time zone.
3. Precise timing of this occultation is critically important.
   Make sure that you are located in an area with good 4G/5G coverage, so the telescope time is as accurate as possible.
4. Identify your observation start time. Since the occultation occurs no longer than 0.1 seconds, your recording time should be two minutes (recording one minute before the event through one minute after the event).
   a. Find the passage time as identified in Step 1 (ensuring you convert UTC to your local time zone).
   b. Subtract one minute from your passage time to determine when your eVscope should begin recording. As a reminder, the goal is to record the event one minute before and one minute after it happens.
   c. Here are two examples:

If you’re observing in Salt Lake City, Utah, the occultation should happen at 05:52 UTC, or 10:52 PM Mountain Time. You will need to start the recording time at 10:51 PM Mountain Time.

If you’re observing in Amarillo, Texas, the occultation should occur at 05:49 UTC, or 11:49 PM Central Time. You will need to start the recording time at 11:48 PM Central Time.

How to detect the occultation of Apophis

Well before the occultation begins:

1. Be sure to check the weather.
We suggest you use the clearoutside app or website.(see p.5 in the User Manual)

2. Clear the memory of your eVscope.
WARNING: this step can take up to 30 minutes – 2 hours depending on your Internet connection.
(see p.9 in the User Manual)

3. Charge the battery of your eVscope
Look for updates to the Unistellar app (Apple Store and Android Play Store).

30 minutes before the occultation:

4. Set up your eVscope and level the tripod
(see p.13 in the User Manual)

5. Launch the Unistellar app
Make sure your smartphone is connected to 4G/5G/Wi-Fi BEFORE launching the app. Then, first launch the app WITHOUT powering on your eVscope.

6. Turn on your eVscope
You can connect your smartphone to your eVscope now.

7. Launch Autonomous Field Detection,
so that your eVscope knows precisely how to go to the occulted star.
(see p.17 in the User Manual)

8. Focus and Collimate your eVscope
In the Explore tab of the app, GoTo one of the first stars recommended. Then focus using the Bathinov Mask. Collimation is optional.
(see p.18 in the User Manual)

15 minutes before the occultation:

9. Go to the star:
In the Science tab of the app, click on Asteroid occultations.
In the Target field, enter the star’s coordinates:
* * *
RA: 10h 20m 50s
Dec: -15° 28’ 41”
* * *
BE CAREFUL: Do not forget the sign before the Dec. Here, click on “-“Check your values one more time. Then, click on GoTo. Your eVscope is now pointing at the star soon to be occulted.You can come back to the eVscope tab while your eVscope is slewing if you want to see the star.

10. In the Recording field, enter the following information:
* * *
Exposure time: 125 ms
Gain: 15 dB
Duration: 02m 00s
* * *
Check your values again, and click on Launch at the launch time determined in the observing section.

Please Note: Once recording has started, you can now switch back to the eVscope tab to try and see the occultation in real time. This is a very difficult event to observe directly. 

Do not activate Enhanced Vision during recording: it will delete your data.

Once you are at home:

11. Transfer your data
Once the recording is over, please transfer your data.
(If you need help, please check out: How To upload my data?)

12. Tell Unistellar that you participated
To make sure your contribution is properly processed, please fill this very short survey by telling us your name, the serial number of your eVscope, and if you agree your name can be mentioned in the IOTA report on their website. (Keep in mind, that to prove the accuracy of your observation, its GPS coordinates will be published too). Please, fill out this survey, we can only process data registered that way.

13. 🥂 Congratulations! 🥂
You have achieved your citizen science mission. Unistellar and SETI Institute scientists thank you and hope you enjoyed it!
It is a small step for you, and a big step for citizen science.

If you have any questions, please contact us at citizenscience@unistellaroptics.com or join our Slack channel (#occultation_na) by clicking here.

Clear skies! 🔭

SETI Institute & the Unistellar Planetary Defense Team