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2 Observations of Radio and X-ray Pulsars
2.8.2 Röntgen Satellite
The ROSAT is a space-based X-ray telescope led by German Aerospace Center,
with instruments jointly built by West Germany, the UK and the US. In Germany,
X-ray is called Röntgenstrahlen for honor of Wilhelm Röntgen, and thus ROSAT
is short for Röntgen Satellite. On June 1, 1990, the satellite was launched from
Cape Canaveral into a nearly circular Earth orbit of 580 km altitude and 53 degrees
inclination. ROSAT carried a German-built imaging X-ray telescope, with three
focal plane instruments, including two German position-sensitive proportional counters and an US-supplied high-resolution imager. The X-ray mirror assembly was a
grazing-incidence fourfold nested Wolter-I telescope with an 84-cm diameter aperture and 240-cm focal length. The angular resolution is less than 5 arc-seconds at
half energy width. The X-ray telescope assembly is sensitive to X-rays in 0.1–2 keV
energy range. In addition, an extreme ultraviolet telescope supplied by the UK is the
wide field camera, co-aligned with the X-ray telescope and covered the energy band
from 0.042 to 0.21 keV. The ROSAT was a three-axis stabilized satellite which could
be used for pointing observations, for slewing between targets, and for performing
scanning observations on great circles perpendicular to the plane of the ecliptic. The
unique strengths of ROSAT are with high spatial resolution, low background and
soft X-ray imaging for studying the structure of low surface features.
The ROSAT was damaged on September 20, 1998 when a reaction wheel in
the satellite’s attitude measuring and control system reached its maximum rotational
speed, losing control of a slew and damaging the high-resolution imager by exposure
of the Sun. Thereby it was difficult to control the satellite under the circumstances
outside its initial design parameters. Finally, the ROSAT stopped working due to the
failure of the attitude control system on February 12, 1999. After that, the satellite
ran aimlessly in space and until October 23, 2011 re-entered the Earth’s atmosphere
to burn out, over the Bay of Bengal in the East of Indian Ocean. The ROSAT worked
normally on the orbit for over 8 years, and obtained a large amount of observation results, including the X-ray all-sky survey catalogue of more than 150,000
objects, extreme ultraviolet all-sky survey catalogue with 479 objects, catalogue of
serendipitous sources with approximately 100,000 from the pointing phase, detailed
morphology of supernova remnants and galactic clusters, detection of shadowing of
diffuse X-ray emission by molecular clouds, detection of pulsations from Geminga,
detection of isolated neutron stars, discovery of X-ray emission from comets and
observation of X-ray emission from the collision of Comet Shoemaker-Levy with
Jupiter.
2 Observations of Radio and X-ray Pulsars
2.8.2 Röntgen Satellite
The ROSAT is a space-based X-ray telescope led by German Aerospace Center,
with instruments jointly built by West Germany, the UK and the US. In Germany,
X-ray is called Röntgenstrahlen for honor of Wilhelm Röntgen, and thus ROSAT
is short for Röntgen Satellite. On June 1, 1990, the satellite was launched from
Cape Canaveral into a nearly circular Earth orbit of 580 km altitude and 53 degrees
inclination. ROSAT carried a German-built imaging X-ray telescope, with three
focal plane instruments, including two German position-sensitive proportional counters and an US-supplied high-resolution imager. The X-ray mirror assembly was a
grazing-incidence fourfold nested Wolter-I telescope with an 84-cm diameter aperture and 240-cm focal length. The angular resolution is less than 5 arc-seconds at
half energy width. The X-ray telescope assembly is sensitive to X-rays in 0.1–2 keV
energy range. In addition, an extreme ultraviolet telescope supplied by the UK is the
wide field camera, co-aligned with the X-ray telescope and covered the energy band
from 0.042 to 0.21 keV. The ROSAT was a three-axis stabilized satellite which could
be used for pointing observations, for slewing between targets, and for performing
scanning observations on great circles perpendicular to the plane of the ecliptic. The
unique strengths of ROSAT are with high spatial resolution, low background and
soft X-ray imaging for studying the structure of low surface features.
The ROSAT was damaged on September 20, 1998 when a reaction wheel in
the satellite’s attitude measuring and control system reached its maximum rotational
speed, losing control of a slew and damaging the high-resolution imager by exposure
of the Sun. Thereby it was difficult to control the satellite under the circumstances
outside its initial design parameters. Finally, the ROSAT stopped working due to the
failure of the attitude control system on February 12, 1999. After that, the satellite
ran aimlessly in space and until October 23, 2011 re-entered the Earth’s atmosphere
to burn out, over the Bay of Bengal in the East of Indian Ocean. The ROSAT worked
normally on the orbit for over 8 years, and obtained a large amount of observation results, including the X-ray all-sky survey catalogue of more than 150,000
objects, extreme ultraviolet all-sky survey catalogue with 479 objects, catalogue of
serendipitous sources with approximately 100,000 from the pointing phase, detailed
morphology of supernova remnants and galactic clusters, detection of shadowing of
diffuse X-ray emission by molecular clouds, detection of pulsations from Geminga,
detection of isolated neutron stars, discovery of X-ray emission from comets and
observation of X-ray emission from the collision of Comet Shoemaker-Levy with
Jupiter.