Transients
What happens in the first hours of an explosion?
Why it matters
The earliest hours of a supernova carry the imprint of what the star was before it exploded — the size of a companion, the extent of circumstellar material, the structure of the outer envelope. That information is gone within days, which is why so few explosions have been caught with spectral coverage early enough to use it.
A survey that samples the spectrum at every visit does not need to decide in advance which transients deserve follow-up. The spectral information is already in the discovery data.
What 7DS contributes
Medium-band spectral sampling gives direct color and continuum information for a transient from one epoch of imaging. A hybrid classification framework built on 7DT spectral energy distributions — an unsupervised anomaly detector coupled to a supervised multiclass classifier — reaches macro F1 ≈ 0.80 across eight common transient types and recovers more than 90 percent of optically detectable kilonovae, including AT2017gfo, without ever being trained on one.
What the program aims to deliver
- Early-time spectral coverage for more than a hundred supernovae, to constrain explosion mechanisms and progenitor systems
These are program targets over the seven years of the survey, not results in hand. What has been observed so far is on the status page, and published work is listed under publications.