Astronomy Picture of the Day 4-6-02

NASA ^ | 4-6-02 | Robert Nemiroff and Jerry Bonnell

[petuniasevan]

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.

2002 April 6

Vintage Gamma Rays
Credit: ESA / IAS / CEA-SACLAY

Explanation: Gamma-rays are the most energetic form of electromagnetic 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 in gamma-ray light? One way is to use a patterned mask of material which can cast gamma-ray shadows on a digital detector array. The mask is called a coded aperture and the resulting shadow patterns can be used to construct a gamma-ray image of the source. For example, consider the picture above. In place of a coded mask, familiar objects were positioned in front of a detector array and illuminated with gamma-rays in a laboratory test. Do you recognize the shadow image? (Click on the picture for the focused visible light image.) Destined to fly on the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite scheduled for launch in October of this year, the detector array is part of the imaging gamma-ray telescope, IBIS.

[petuniasevan]

Yes it loaded completely!
This image may be strange but it does illustrate the process used to image gamma ray sources in space,
and the difficulty in getting clear images of those sources.
The detector which made the image will be a part of an Earth-orbiting gamma ray telescope come October.
Click on the photo to see the objects in visible light.

As always, ask to be added to the APOD PING list or subscribe to the General Interest topic Astronomy Picture of the Day!

[petuniasevan]

APOD PING!

[Jeff Chandler]

I recognized it immediately. Do you suppose I have a problem?

[petuniasevan]

LOL! !

Not by Wisconsin standards!