1572 · 1604 · 1987A

LITTransients are the ephemeral sky. Tycho's supernova of 1572 (Cassiopeia) and Kepler's of 1604 broke the "unchanging heavens". SN 1987A in the Large Magellanic Cloud (about 51.4 kpc) peaked near magnitude 2.9, and its tail followed ⁵⁶Co decay (half-life 77.2 d, after ⁵⁶Ni at 6.08 d). Type II supernovae show H-alpha, cross-link to H-alpha 656.28 nm; Type Ia have no hydrogen. Today, surveys (ZTF; the Rubin Observatory's LSST) send automated alerts, millions per night for Rubin (design figure, approximate), the ephemeris of the ephemeral.

COMPUTEDA toy radioactive light curve: tap the sky to set off a transient.

set off a transient

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