Fermi-GBM Observations of GRB 210812A: Signatures of a Million Solar Mass Gravitational Lens

Understand

Observing gravitationally lensed objects in the time domain is difficult, and well-observed time-varying sources are rare.

• Lensed gamma-ray bursts (GRBs) offer improved timing precision to this class of objects complementing observations of quasars and supernovae.
• The rate of lensed GRBs is highly uncertain, approximately 1 in 1000.
• The Gamma-ray Burst Monitor (GBM) onboard the Fermi Gamma-ray Space Telescope has observed more than 3000 GRBs making it an ideal instrument to uncover lensed bursts.