1. What is an Asteroid?

Asteroids are small bodies, usually rocky, that mainly populate a region of the solar system between the orbits of Mars and Jupiter known as the main asteroid belt. However, they can also be found throughout the solar system. As remains of the formation of the solar system, these bodies bear the signature of the birth of our planetary system. Its properties allow to demonstrate current theories and to open doors to the development of new theories belonging to different evolutionary processes in the solar system.

2. Who can be a Hunter (Cazasteroides in Spanish)?

Anyone who has an Android mobile, iOS or simply from a web browser.

3. Do I have to create an account to collaborate?

Yes, you can create an account with your email or, if you prefer, access with your Facebook user.

4. Can I really collaborate with Science through this project?

Yes. Every year hundreds of smaller objects are discovered, such as asteroids. This requires accurate and continuous observations of the sky to avoid an impact of an asteroid against the Earth. Your collaboration can be very important to analyze images of the sky and thus detect new asteroids and keep updated the databases of such objects.

5. Are there any scientists behind this project?

Yes, Miquel Serra Ricart, an astronomer at the Instituto Astrofísico de Canarias (IAC) and the administrator of the Observatorio del Teide, has been the designer of the application and the person who provides the images captured with some of his telescopes. Subsequently, he and other astronomers who collaborate with him will analyze the “candidate asteroids” to determine the validity of the data sent by users.

6.What is seen in the image?

It really does not show a single image, it shows a sequence of five images (this is known as time-lapse) of a part of the sky. The images are shown quickly so you can see if there is any object that moves on the fixed background of stars and which could be an asteroid.

Gif de secuencia de imágenes

7. Why is there a chronometer?

We want to reward the fastest hunters and therefore the speed in detection is important. So the faster you detect them, the more points you get in your account.

8. Which is the formula to get points?

8.1. By detecting “candidate” asteroids

When users add a detection, their can obtain points according to the formula presented below. The points will not be counted until the astronomer confirms the detection (positively or negatively), as follows:

  • If the astronomer positively confirms the detection, then the user (or users) who have detected will receive the points according to the formula described below.
  • If the astronomer negatively confirms the detection, then no points are received.

Clarification: A user can only detect in certain coordinates once.

In the formula there are the next five parameters:

P1) Time. The user will have more points if their find the asteroid faster.

P2) Order on detection. The first to detect a candidate will have the highest score.

P3) Probability of finding an asteroid in the field (calculated from the ecliptic latitude of the field). There is a PROBA header with that value. For fields where the probability of finding an asteroid is high, the points will be less.

P4) Brightness or magnitude of the asteroid. If the brightness of the asteroid is high it will have fewer points than the detection of weak asteroids. At the end of the section I put the details to calculate the magnitude of an asteroid from the maximum of light.

P5) Seeing or fwhm. There will be a parameter in the header called FWHM that will indicate the degree of turbulence or “seeing” of the night. Detecting an asteroid with bad seeing should have more points than with a good night.

The points are defined by the following formula:

FINAL = 40% p1 + 30% p2 + 10% p3 + 10% p4 + 10% p5



// input parameters (time in milliseconds)

calculateProTime(time) {    

        var sigma = 2.1;

        var x = time / 1000 / 60;

        return 526 * (Math.pow(Math.E, -((Math.pow(x, 2)) / (2 * Math.pow(sigma, 2))))) / (sigma * Math.sqrt(2 * Math.PI));



// input parameters: order of observation (0 if it is the first to report, 1 if it is the second …)

calculateProOrd(ord) {

        var sigma = 0.399;

        var x = ord / 10;

        return 100 * (Math.pow(Math.E, -((Math.pow(x, 2)) / (2 * Math.pow(sigma, 2))))) / (sigma * Math.sqrt(2 * Math.PI));



100 – metadata.PROBA


calculateProBright(bright) {

        var b = 0.6;

        return 100 * (1 / (1 + (Math.pow(Math.E, -(b * (bright - 15))))));



// input parameters (metadata.SCALE, metadata.FWHM)

calculateProFWHM(scale, fwhm) {

        return 100 * (1 / (1 + (Math.pow(Math.E, -(scale * fwhm) + 1))));


8.2. By votes from the detections of other users

The user who has made a detection can NOT vote for themselves or vote the same detection more than once. Points are not counted until the astronomer confirms the detection (positively or negatively).

When a user enters to vote only sees the total number of votes. After the vote, yes is shown the votes for and against.

The points that are obtained by the votes are:

  • If the astronomer positively confirms the detection:
    • Positive vote gets 30% of the points of the maximum score of the detection (usually the score of the first user but not necessarily).
    • Negative feedback does not get points.
  • If the astronomer negatively confirms the detection:
    • Positive vote does not get points.
    • Negative feedback receives a constant score (5 points). 

9. What are the points for?

At the moment points serve for recognition. We will publish regularly in our social channels those users in the best positions of the rankings.

(We will be posting more FAQs as we get feedback from the app. Thanks for your cooperation).