What Is a Kilonova?#
A kilonova is a rare and powerful event that occurs when two neutron stars — or a neutron star and a black hole — collide.
These collisions release a huge amount of energy, producing:
Gravitational waves (ripples in space-time)
A flash of gamma rays
And an optical/infrared light show that fades over days to weeks
This optical event is what we call a kilonova.
Where Do Kilonovae Come From?#
Neutron stars are the super-dense remnants of massive stars that exploded as supernovae. If two neutron stars orbit each other in a binary system, they slowly spiral in due to gravitational radiation.
Eventually, they crash into each other in a violent merger.
This merger ejects hot, radioactive material into space — the r-process material — which creates some of the heaviest elements in the universe, including gold, platinum, and uranium.
Why Are Kilonovae Important?#
Kilonovae are a unique window into some of the most extreme physics in the universe. Studying them helps us:
Understand how heavy elements are made (nucleosynthesis)
Test predictions of general relativity
Pin down the physics of dense matter
Study the life cycle of stars and galaxies
They’re also the optical counterparts to gravitational wave (GW) events. By observing both the light and the ripples in spacetime from the same event, we unlock multi-messenger astronomy — a new era in understanding the cosmos.
How Do We Find Them?#
Most kilonova searches start with a gravitational wave alert.
When LIGO, Virgo, or KAGRA detect a possible neutron star merger, they send out a GW alert through the General Coordinates Network (GCN). This alert contains:
A timestamp of the merger
A probability map showing where in the sky it likely happened
Information about the source (like if it involved neutron stars)
Telescopes all over the world — including amateurs like you — use this alert to look for any new, fast-fading sources of light in the region of interest.
If we find a new source that wasn’t there before, and it’s fading over days, it could be a kilonova.
What Does a Kilonova Light Curve Look Like?#
A kilonova is a fast transient, meaning it brightens and fades rapidly.
In blue light (g-band), it may peak in less than 1 day and fade quickly.
In redder bands (i- or z-band), it may last a bit longer — several days.
The brightness depends on how much material was ejected, what it’s made of, and how far away the event was.
Because of how quickly kilonovae fade, fast follow-up is essential — every hour counts.
By helping us capture early images of these events, your observations as part of Kilonova Catcher contribute directly to frontier science. And with this manual, you’ll be ready to do just that.