APOD: 2000 June 30 - Vintage Gamma Rays (original) (raw)

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2000 June 30

Explanation: Gamma-rays are the most energetic form ofelectromagnetic radiation. But these high energy photons penetrate and interact in normal materials and cannot be focused by lenses and mirrors like those in optical telescopes. So how do you make an image ingamma-ray light? One way is to use a patterned mask of material which can cast gamma-rayshadowson a digital detector array. The mask is called acoded aperture and the resulting shadow patterns can be used to construct a gamma-ray image of the source. For example, considerthe picture above. In place of acoded mask, familiar objects were positioned in front of a detector array and illuminated with gamma-rays in a laboratory test. Do you recognizethe shadow image? (Click on the picture for the focused visible light image.) Destined to fly on theInternational Gamma-Ray Astrophysics Laboratory(INTEGRAL) satellite scheduled for launch in 2002, the detector array will be part of the imaging gamma-ray telescope,IBIS.