Evidence for penguin-diagram decays: First observation of<i>B</i>→<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="italic">K</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">*</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:math>(892)γ

We have observed the decays ${\mathit{B}}^{0}$\ensuremath{\rightarrow}${\mathit{K}}^{\mathrm{*}}$(892${)}^{0}$\ensuremath{\gamma} and ${\mathit{B}}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${\mathit{K}}^{\mathrm{*}}$(892${)}^{\mathrm{\ensuremath{-}}}$\ensuremath{\gamma}, which are evidence for the quark-level process b\ensuremath{\rightarrow}s\ensuremath{\gamma}. The average branching fraction is (4.5\ifmmode\pm\else\textpm\fi{}1.5\ifmmode\pm\else\textpm\fi{}0.9)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$. This value is consistent with standard model predictions from electromagnetic penguin diagrams.