While
radio waves, near-infrared (near-IR), and
visible light are observable from surface of
the Earth, we need to introduce tools into space to
observe other frequencies of the
EM-band.
This
section will introduce:
Near-IR
Infrared
X-Ray
Ultraviolet
Gamma Ray
Near-IR:
In order to see the small window of the near-IR
spectrum from the ground, some novel approaches have
been designed and implemented. Viewing of the near-IR
is possible only by:
- Very high altitude
- Using super-cooled
CCD imagery
- Mirrors using silver or gold coated mirrors
- Small secondary mirrors
- Cooled
telescope tubes and housings of
mirrors along the optical path
An example of an infrared optimized
telescope is
the Keck Observatory
Gemini-North telescope.
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Infrared:
To view the residual IR spectrum, high altitude
observatories - or orbiting satellites - are required.
Another method is to observe from Antarctica - if
you like the cold!
There are two in-flight observatories:
In addition, the following observatories are (and
were) in orbit around the Earth:
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X-Ray:
This high-energy portion of the
EM-band is only
visible from space. Between 1949 to 1962, sounding
rockets traveling up to 100 km above the surface
would carry Geiger counters to measure X-ray
emission. A sounding rocket is nothing more than a
standard rocket with the Geiger counter and other
related electronics housed in within the nose.
By 1970, several orbiting X-ray observatories
would begin capturing valuable data. These include
the following observatories:
Objects observed by X-ray are (but not limited
to)
supernova remnants, accretion disks, pulsars,
and black holes.
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Ultraviolet:
The ultraviolet (UV) region of the
EM-band allows
the study of very hot, young
stars. Additionally,
populations of young, hot
stars within the disks of
spiral
galaxies are within easy view of a UV
telescope. This also requires satellite
observatories. Here is a list of UV observatories:
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Gamma Rays:
Gamma rays are the highest energy radiation
resulting in extremely short wavelengths. Sources of
gamma rays are
supernovas, neutron
stars, intense
gravity regions and active
galaxies (galaxies with a
large and active black hole at the center). Here is
a list of some gamma ray satellites:
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