Embargoed Until: 01 July 2025 (Provisional) – Final Date TBC
The Kilonova Seekers Project is approaching its two-year anniversary of inviting members of the public to analyse near real-time data collected from the Gravitational-wave Optical Transient Observer (GOTO) project. This project takes all-sky survey images of space from two arrays of telescopes located on opposite sides of the planet – in Spain and Australia.
Previously described as playing astronomical ‘spot the difference,’ Kilonova Seekers asks the public to compare the latest images of a section of night sky to an image of the same section of space taken on previous nights. Their goal – to spot new stars or significant changes in light intensity that may indicate that something remarkable has happened in space.
Published today in the journal Astronomy & Astrophysics, Kilonova Seekers has announced its first published major discovery – an object that underwent an extreme brightening (by a factor 2500 in a matter of days) that was not seen when compared to the image taken ~2 days earlier. The quick response and diligent work of the public allowed the object to be studied and classified early in its evolution, identifying it as a cataclysmic variable star, and given the name GOTO0650.
Armagh Astronomer, Prof Gavin Ramsay, and lead of Armagh’s involvement in GOTO and Co-Chair of the GOTO Executive Board said “This was a very bright eruption of an object which wasn’t previously known as being such an exciting object. What was very interesting about the eruption was that after it started to fade, it experienced another ten outbursts of much shorter duration. Observations of these repeating outbursts, which amateur astronomers helped obtain, are used to test theoretical models of accretion flows and discs. The kilonova Seekers have discovered several dozen of supernovae, but this is the first time they found such an exciting object located in our own Milky Way. We look forward to many more discoveries in the future”.
The discovery image that the Kilonova Seekers volunteers first saw of GOTO0650 when it went into outburst. The science, reference, and difference images are shown: the “science” image taken on the night of discovery, the “reference” image taken a few months prior under the best sky conditions, and the “difference” image which uses an algorithm to subtract out all objects which have not changed in brightness between the science and reference. The very bright star in both the science and difference images is the object itself – it brightened by about a factor of 2500x. Image Credit: GOTO, T. Killestein
Co-lead of Kilonova Seekers, Dr. Tom Killestein, Warwick Prize Fellow in the Astronomy and Astrophysics group at the University of Warwick said: “Kilonova Seekers is a unique opportunity for members of the public to take part in true real-time astrophysics. Remarkably, public volunteers identified this star as an object of interest within 3 1/2 hours of the image being taken by the GOTO telescopes – this discovery could have been missed among many other objects without their efforts”
“The involvement of the volunteers didn’t stop there, as there was a huge follow-up response from the public. It was flagged for further observations from the Swift and Einstein Probe space observatories, and GOTO0650 was bright enough for amateur astronomers to take impressively high-quality observations of with their own equipment, which formed a key part of the paper and really helped us understand the object.”
Cataclysmic variable stars sporadically increase in brightness by large amounts before dropping back to normal levels. They are compact binary star systems, consisting of a white dwarf star stealing matter from its companion donor star. Periodically, material from the donor star hits a critical density and temperature within the disc of gas that surrounds the white dwarf, which causes an explosive outburst and bright flashes of light.
The fast response of the public enabled the team to get an unusually highly complete dataset on the star, including spectroscopy, X-ray, and UV measurements. This was supplemented by the impressively high-quality observations of the amateur astronomers, co-ordinated via the American Association of Variable Star Observers (AAVSO), and observations with the Las Cumbres Observatory’s 0.4m worldwide network of robotic telescopes, via the Kilonova Seekers Global Sky Partnership. These observations suggest it is a period bouncer, the final state of a cataclysmic variable star, and a rare object to find even in the age of widespread wide-field imaging surveys.
Co-lead of Kilonova Seekers, Dr Lisa Kelsey, Leverhulme Early Career Fellow, Institute of Astronomy and Kavli Institute for Cosmology, Cambridge said: “Citizen science is a powerful way to make novel serendipitous discoveries in vast datasets that would normally need to be analysed in depth by scientists.
“With over 2.8 million classifications so far, the discovery of GOTO0650 is really the pinnacle of 2 years of consistent hard work from our volunteers. Without the Kilonova Seekers volunteers flagging this object, rapid follow-up would not have been possible, and this object may have been missed entirely.”
The vast numbers of observations taken in these imaging surveys will soon be beyond the capacity of individual and small teams of scientists to label and validate. Citizen Science is a viable, mutually beneficial solution to avoid objects like GOTO0650 being missed.
As a shining example of such efforts, Kilonova Seekers has provided over 3,500 members of the public with the opportunity to discover supernovae and variable stars using real data. With volunteers from around the world, there is almost always someone online looking at the data in real-time.
The announcement of the first published discovery is a fitting way to celebrate two years of kilonova seeking, and this discovery means just as much to the volunteers who not only give their time to astronomical discovery but have formed a community around it.
Svetoslav Alexandrov, Kilonova Seekers Volunteer said: “Traffic in Sofia, Bulgaria, is always awful during the mornings so I have to pass time on the bus somehow, and contributing to citizen science is an excellent way to do that! Kilonova Seekers is on the top of my list, because it’s mobile-friendly and most importantly, it offers us fresh imagery almost every single day.”
“I literally screamed with joy when I saw that I was going to be a co-author of the research paper. I’m certain that people on the street raised their eyebrows when they saw me screaming and dancing, but I didn’t care. I knew I am a co-discoverer of something significant, and this was all that mattered”
Cledison Marcos da Silva, Kilonova Seekers Volunteer said: “This discovery was very important to me, as I was going through a serious health problem and the citizen science we do at Kilonova Seekers was distracting me from my situation. I never imagined that we would discover such a bright transient, so it was a huge surprise, and we were very happy when we found out. This discovery shows the importance of citizen science, both scientifically and personally. Even from your bed, or on the street with your cell phone, there is the possibility of making a very important discovery.”
Mayahuel Torres-Guerrero, Kilonova Seekers Volunteer said: “The journey from the discovery of GOTO0650 to the publication of the paper in Astronomy & Astrophysics has been personally rewarding. I had the opportunity to learn how to download data from LCO telescopes and to produce light curves that allowed us to monitor echo outbursts. It was very exciting when GOTO0650 produced an echo outburst on Christmas Day and New Year’s Day! It was a great journey for someone who has studied social sciences like me!”
Images of the GOTO0650 outburst, made from GOTO’s all-sky survey images. Image Credit: GOTO, T. Killestein and K. Ulaczyk
Access the Paper about this discovery here.