High-magnification deep optical view into AT2016hkr's host environment. Pan and scroll to explore the cosmic neighborhood where this star exploded.
⚡ Quick Observer Facts & Telemetry
IAU Transients DBThe Iron Core Collapse of a Dying Supergiant
On 2016/10/25, astronomers scanning the heavens flagged a sudden, violent pinpoint of light that had flared into visibility. Designated AT2016hkr, it represents a catastrophic stellar explosion classified as a Type Candidate supernova.
The progenitor of AT2016hkr was a mammoth supergiant star, shining with the furious vigor of an object at least 8 to 25 times more massive than our Sun. For millions of years, it synthesized heavier and heavier elements in concentric onion-like shells: hydrogen burning into helium, helium into carbon, carbon into oxygen, neon, and silicon. But when silicon fused into iron, the stellar engine ran out of fuel. Iron fusion absorbs energy rather than liberating it; within fractions of a second, the iron core collapsed under its own gravity, rebounding into an immense cosmic shockwave that blasted the star into pieces.
A Message Across Deep Cosmic Time
The light from AT2016hkr is a dispatch from an ancient past. Located approximately 304.5 Million Light-Years away
(redshift z = 0.020764), the photons detected by telescopes today began their journey
304.5 million years ago during the Paleozoic era, long before the first dinosaurs appeared on Earth.
While this burst of electromagnetic radiation traversed the cold void of intergalactic space at 299,792 kilometers per second, continents on Earth drifted, mountain ranges rose, and entire ecosystems rose and fell. To look into a telescope at AT2016hkr is to gaze directly into prehistoric cosmic time.
Incandescence of 1.8 billion Suns
At the height of the outburst around 2016/10/28, AT2016hkr surged to a peak apparent magnitude of 16.5 and an intrinsic absolute magnitude of -18.3282. At that instant, this single dying star radiated with the collective power of approximately 1.8 billion Suns combined, outshining whole dwarf galaxies and illuminating the surrounding interstellar medium.
The total energy released by the cataclysm was on the order of 10⁵¹ to 10⁵³ ergs. Over 99% of this energy was emitted within the first 10 seconds as a dense burst of trillions of neutrinos, with only 1% driving the visible blast wave.
The Radioactive Furnace: Why Supernovae Glow for Months
Unlike a conventional terrestrial explosion that cools and goes dark in seconds, AT2016hkr shone brightly for weeks and months. The secret behind this prolonged celestial glow is nuclear physics: the extreme heat and pressure of detonation synthesized vast quantities of radioactive Nickel-56 (⁵⁶Ni).
With a half-life of 6.075 days, Nickel-56 decays into Cobalt-56 (⁵⁶Co), emitting gamma rays and high-energy positrons that heat the expanding ejecta from within. Cobalt-56 in turn decays with a half-life of 77.2 days into stable Iron-56 (⁵⁶Fe), powering the steady exponential radioactive tail observed in the light curve.
Cosmic Kiln: Seeding the Elements of Life
Supernovae are the premier chemical foundries of our universe. AT2016hkr forged and liberated tons of newly synthesized elements: vast reservoirs of oxygen (the most abundant heavy element in living organisms), carbon, nitrogen, magnesium, and silicon.
As Carl Sagan famously observed, "We are made of star-stuff." The iron atoms that carry oxygen in human hemoglobin and the calcium in our bones were originally forged in explosions identical to AT2016hkr billions of years ago.
Galactic Setting in Hercules
AT2016hkr detonated inside NGC 6321.
In our terrestrial sky, it resides in the constellation Hercules (Hercules) at Right Ascension 17:14:27.730
and Declination +20:18:19.10.
The Scientific Surveillance Campaign
Following its discovery by Tim Puckett et al., observatories worldwide swung their lenses toward AT2016hkr.
In the Open Supernova Catalog, AT2016hkr is documented across 12 photometric measurements
in passbands such as G and 0 spectroscopic epochs.
These multi-wavelength observations allow astrophysicists to model the expanding photosphere, measure shock velocities, and probe circumstellar interactions.
Stargazer's Field Guide: Can You See It Tonight?
Can I see it tonight? No — this supernova is physically extinguished.
Supernovae are brief, explosive cosmic catastrophes. They brighten over days to weeks and then permanently fade into darkness as their radioactive nickel-56 and cobalt-56 fuel decays. This explosion occurred 9.9 years ago (2016/10/28). Accounting for cosmological time dilation at redshift z = 0.0208, the rest-frame age is +3552.2 days. By standard radioactive decay templates, its optical brightness has decayed by Δm ≈ 50.3 magnitudes to an estimated magnitude 66.8, rendering the transient undetectable to all ground-based observatories.
Instrument Breakdown: At its maximum brightness in 2016/10/28, it reached magnitude 16.50 (Amateur CMOS Rig). Tonight, pointing a telescope at these coordinates will reveal only the background host galaxy (NGC 6321).
| Instrument Class & Aperture | Sensitivity Limit | At Peak Maximum (m=16.50) | Tonight (Est. m≈66.8) |
|---|---|---|---|
| Naked Eye Dark sky site (Bortle 1–3) with no optical aid |
m ≤ 6.0 | ❌ Below limit | ❌ Below limit |
| Binoculars (50mm) Standard 7x50 or 10x50 handheld binoculars |
m ≤ 9.5 | ❌ Below limit | ❌ Below limit |
| Small Backyard Scope (4" / 100mm) Entry 4-inch (100mm) refractor / reflector |
m ≤ 12.0 | ❌ Below limit | ❌ Below limit |
| Medium Amateur Scope (8"–12") 8-inch to 12-inch Dobsonian or Schmidt-Cassegrain |
m ≤ 14.5 | ❌ Below limit | ❌ Below limit |
| Amateur CMOS Rig Cooled monochrome/color CMOS camera with multi-hour stack |
m ≤ 19.5 | ✅ Detectable | ❌ Below limit |
| 2m–3m Research Telescope University or regional observatory (e.g. Palomar 60", Calar Alto) |
m ≤ 22.0 | ✅ Detectable | ❌ Below limit |
| Giant 8m–10m Observatories Keck (10m), VLT (8.2m), Gemini, Subaru optical imaging |
m ≤ 25.0 | ✅ Detectable | ❌ Below limit |
| Space Observatories Only Hubble Space Telescope (WFC3) / JWST (NIRCam deep stack) |
m ≤ 30.0 | ✅ Detectable | ❌ Below limit |
Planetary Safety Note: Even though AT2016hkr was a titanic explosion, our planet sits safely outside the lethal 50–100 light-year kill zone. At a distance of 304.5 Million Light-Years, the blast poses zero physical hazard to Earth's biosphere.
Cataloged supernovae closest to AT2016hkr in discovery time, spatial sky neighborhood, and cosmological lookback epoch:
❓ Frequently Asked Questions About AT2016hkr
What type of supernova is AT2016hkr and what kind of star exploded? Astrophysics & Progenitor
What was the progenitor star doing in the millions of years leading up to AT2016hkr? Astrophysics & Progenitor
How far away is AT2016hkr from Earth and how old is the light reaching us? Cosmic Distance & Time
What does the cosmological redshift of AT2016hkr tell us about the expansion of space? Cosmic Distance & Time
How bright did AT2016hkr become at its peak, and how many Suns does that equal? Explosion Energetics
How much total energy was released by AT2016hkr, and where did that energy go? Explosion Energetics
How fast are the supernova ejecta and shockwave of AT2016hkr expanding through space? Explosion Energetics
What powers the prolonged glow of AT2016hkr weeks and months after detonation? Radioactive Engine
What chemical elements did AT2016hkr create and disperse into the universe? Nucleosynthesis & Elements
Did AT2016hkr leave behind a black hole, a neutron star, or nothing at all? Cosmic Remnant
What will AT2016hkr's explosion site look like in 1,000 to 10,000 years? Cosmic Remnant
In which galaxy did AT2016hkr explode, and where is it located relative to the galactic center? Galactic Environment
Where is AT2016hkr located in the night sky and which constellation is it in? Sky Coordinates
How much Milky Way interstellar dust obscures our view of AT2016hkr? Interstellar Dust
Across which photometric filter bands was AT2016hkr monitored? Astronomical Observations
G. Data were captured by observatories and survey networks including GAIA. Multi-color photometry tracks the temperature evolution of the fireball, verifying the rise time to peak and the rate of radioactive decline.What did astronomical spectroscopy reveal about AT2016hkr's chemical makeup? Astronomical Observations
Who discovered AT2016hkr and how was it first detected? Discovery & History
How many scientific publications and observatories have contributed data to AT2016hkr? Scientific Research
What other names and survey identifiers exist for AT2016hkr? Cross-Identifications
Gaia16brg. These cross-matched identifiers allow astronomers to cross-reference observations across the Zwicky Transient Facility (ZTF), the Asteroid Terrestrial-impact Last Alert System (ATLAS), Pan-STARRS, Gaia Photometric Science Alerts, and the IAU Transient Name Server (TNS).