The phrase "telltale signature" refers to a unique and easily recognizable sign or clue that unmistakably identifies or signifies a certain person, object, or action. Full definition
Guardian is developing PinPoint, a software system that can analyze X-ray images of carry - on bags for telltale signatures of dangerous substances. (discovermagazine.com)
When a planet travels in front of its star, some of the starlight passes through the atmosphere, and some of the atmospheric gases leave telltale signatures on that starlight. (discovermagazine.com)
Cyclotron resonance scattering creates telltale signatures in a star's spectrum of light and the presence of these patterns, called cyclotron lines, can provide information about the strength of the star's magnetic field — but only if the cause of the lines, whether it be protons or electrons, is known. (sciencedaily.com)