Planet Hunters CHEOPS

Project statistics since launch on 13 October 2026

When Planet Hunters CHEOPS launched on 13 October 2026, the response went far beyond what we hoped for. Volunteers made 50,000 classifications before the first day was over and 100,000 in two days, and the whole batch was finished in under a week. A new volunteer joined every 2 minutes, and 1,000 had joined within the first day and a half. Alone, this work would have taken one person more than four months of full-time effort. Together, you did it in six days. Thank you!

• 227,840 classifications.
• About 1,640 volunteers. 828 of them were registered and about 810 classified without logging in.
• 5,000 light curves, each checked by about 50 volunteers.
• The batch was done in less than a week. Almost all classifications came in between 13 and 19 October.
• Launch day was the busiest day, with 55,412 classifications. At the busiest hour (15:00–16:00 UTC) there were 7,212, and at the peak minute 244, which is about 4 per second.
• The project never slept. Every hour of the day, round the clock, brought in at least 3,690 classifications.
• About 774 hours of volunteer time, which is roughly 32 days of looking at light curves without stopping. Each classification counts for at most 5 minutes, to leave out idle time.
• A typical light curve took under 4 seconds to judge (median 3.5 s).
• Volunteers’ browsers were set to 21 time zones, from Hawaii to New Zealand:
o Europe (UTC+1/+2) had the most, about 47% of classifications.
o The Americas came next, at about 32%.
o The rest came from the Middle East, India, East Asia and Australia.
• Five interface languages were used: English, Spanish, Japanese, Italian and Portuguese.
• Everyone helped, and some helped a lot:
o 328 volunteers did 100 or more classifications.
o 51 did 1,000 or more.
o The five most active volunteers did between 4,900 and 5,000 each.

What you have helped us find so far

An interim results update from Planet Hunters CHEOPS
PROJECT: Planet Hunters CHEOPS
STATUS: Work in progress — findings are still being checked

Thanks to the care and curiosity of Planet Hunters CHEOPS volunteers, we are building a valuable collection of unusual and scientifically interesting signals in CHEOPS observations. Your classifications are helping the science team identify possible planetary transits, stellar flares, variable stars and features caused by the spacecraft or data processing.

This page shares some of our first findings. They are interim results rather than confirmed discoveries: each promising signal must be tested against other observations and possible instrumental effects before we can draw firm conclusions.

A possible transit around a background star: A promising signal near K2-136

One of the most intriguing light curves came from a CHEOPS observation of K2-136, a system already known to host planets. Volunteers spotted a transit-like dip in a background star in the same field of view (RA 04h 29m 38.99s, Dec +22° 52′ 57.8″; see figure).

To test whether the signal was a real planet, we analyzed the background star in all nine public CHEOPS observations of K2-136. We also ruled out or confirmed the usual impostors: stray light, roll-angle effects, detector systematics, stellar variability, and ramp effects. The dip did not repeat and is attributed to granulation, so it is not a planetary transit.

This candidate didn’t survive, but it shows what this project can do. Your eyes picked out a very interesting subtle signal in a star nobody was looking at, and that is exactly how new planets are found. Thousands of these background stars have never been examined in detail, and the next real transit could be in the next batch of light curves. Keep classifying: the next dip you mark could be a new world.

More than transits

Volunteer classifications have also highlighted several strong stellar flares and variable background stars. These are scientifically useful findings in their own right. They help us understand how stars change over time, provide examples for improving volunteer guidance and may support future studies using automated or machine-learning methods.

We are reviewing representative examples before publishing them. We are also checking apparently similar light curves, including observations of AU Microscopii, to determine whether they are duplicate data or independent visits.

Speaking of AU Microscopii, our results suggest that it is the most active star of this first batch, with many subjects showing its impressive activity. However, we were excited to find that it wasn’t the only flaring star: thanks to your classifications, we detected both clear and possible activity from a few other stars, and they’re no less intriguing!

A NOTE OF CAUTION

Short visits, light curves that have not been detrended, and ramp-like modulation can resemble astrophysical signals. An unusual dip is a starting point for investigation—not yet a discovery.

How your classifications are improving the project

The broad classification question will remain in place so that volunteers can continue to flag transits, flares, variability and anything else that looks unusual. At the same time, we are preparing clearer guidance for short observations and common instrumental signatures.

For the next data release, we plan to add a simple indicator showing whether a light curve has been detrended. Target names will remain hidden during the main classification task to reduce bias and keep classifications consistent. Names may be shared after classification or in a future advanced project.

Thank you

Every classification helps narrow a very large dataset into signals that scientists can examine in detail. Whether you identify a possible transit, a flare, stellar variability or an instrumental feature, your contribution improves both the scientific search and our understanding of the data.

Thank you to everyone taking part in Planet Hunters CHEOPS.

Next batch of data is coming up!

We will share further updates as the checks progress and as new data batch will become available in the website on the 2nd of November of 2026.

Stay tuned !!