Gamma (satellite)
Encyclopedia
Gamma was a Soviet gamma ray telescope. It was launched on 11 July 1990 into an orbit around Earth
with a height of 375 km and an inclination
of 51.6 degrees. It lasted for around 2 years. On board the mission were three telescopes, all of which could be pointed at the same source. The project was a joint Soviet-French
project.
s and a gas Cerenkov counter. With an effective area of around 0.2 square metres (2.2 sq ft), it operated in the energy range of 50 MeV
to 6 GeV
. At 100 MeV it initially had an angular resolution
of 1.5 degree
s, with a field of view
of 5 degrees and an energy resolution of 12%. A Telezvezda star tracker increased the pointing position accuracy of the Gamma-1 telescope to 2 arcminutes by tracking stars up to an apparent magnitude
of 5 within its 6 by 6 degree field of view. However, due to the failure of power to a spark chamber, for most of the mission the resolution was around 10 degrees.
The telescope was conceived in 1965, as part of a Cloud Space Station. Work on Gamma began in 1972, and it became a joint venture with France
in 1974. However, also in 1974, the MKBS/MOK space station complex (as the Cloud Space Station had evolved into by then) was cancelled. A few years later, in February 1976, the Soviet space program was reconfigured, and on 16 February 1979 production of the telescope was authorized. The telescope was originally planned to be launched in 1984, but technical delays pushed the launch back to 1990.
- 5 MeV. It consisted of Sodium iodide
scintillation crystal
s, and had an angular resolution of 25 arcminutes. However, it stopped working shortly after the mission was launched.
Finally, the Pulsar X-2 telescope had 30 arcminute resolution and a 10 deg x 10 deg field of view, and operated in the energy range 2-25 keV.
Observations included studies of the Vela Pulsar
, the Galactic Centre, Cygnus X-1
, Hercules X-1
and the Crab Nebula
. The telescopes also measured the Sun
during peak solar activity.
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
with a height of 375 km and an inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...
of 51.6 degrees. It lasted for around 2 years. On board the mission were three telescopes, all of which could be pointed at the same source. The project was a joint Soviet-French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
project.
Background
The Gamma-1 telescope was the main telescope. It consisted of 2 scintillation counterScintillation counter
A scintillation counter measures ionizing radiation. The sensor, called a scintillator, consists of a transparent crystal, usually phosphor, plastic , or organic liquid that fluoresces when struck by ionizing radiation. A sensitive photomultiplier tube measures the light from the crystal...
s and a gas Cerenkov counter. With an effective area of around 0.2 square metres (2.2 sq ft), it operated in the energy range of 50 MeV
MEV
MeV and meV are multiples and submultiples of the electron volt unit referring to 1,000,000 eV and 0.001 eV, respectively.Mev or MEV may refer to:In entertainment:* Musica Elettronica Viva, an Italian musical group...
to 6 GeV
GEV
GEV or GeV may stand for:*GeV or gigaelectronvolt, a unit of energy equal to billion electron volts*GEV or Grid Enabled Vehicle that is fully or partially powered by the electric grid, see plug-in electric vehicle...
. At 100 MeV it initially had an angular resolution
Angular resolution
Angular resolution, or spatial resolution, describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object...
of 1.5 degree
Degree (angle)
A degree , usually denoted by ° , is a measurement of plane angle, representing 1⁄360 of a full rotation; one degree is equivalent to π/180 radians...
s, with a field of view
Field of view
The field of view is the extent of the observable world that is seen at any given moment....
of 5 degrees and an energy resolution of 12%. A Telezvezda star tracker increased the pointing position accuracy of the Gamma-1 telescope to 2 arcminutes by tracking stars up to an apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of 5 within its 6 by 6 degree field of view. However, due to the failure of power to a spark chamber, for most of the mission the resolution was around 10 degrees.
The telescope was conceived in 1965, as part of a Cloud Space Station. Work on Gamma began in 1972, and it became a joint venture with France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
in 1974. However, also in 1974, the MKBS/MOK space station complex (as the Cloud Space Station had evolved into by then) was cancelled. A few years later, in February 1976, the Soviet space program was reconfigured, and on 16 February 1979 production of the telescope was authorized. The telescope was originally planned to be launched in 1984, but technical delays pushed the launch back to 1990.
Operation
The Disk-M telescope operated in the energy range 20 keVKev
Kev can refer to:*Kev Hawkins, a fictional character.*Kevin, a given name occasionally shortened to "Kev".*Kiloelectronvolt, a unit of energy who symbol is "KeV".* Krefelder Eislauf-VereinKEV can refer to:...
- 5 MeV. It consisted of Sodium iodide
Sodium iodide
Sodium iodide is a white, crystalline salt with chemical formula NaI used in radiation detection, treatment of iodine deficiency, and as a reactant in the Finkelstein reaction.-Uses:Sodium iodide is commonly used to treat and prevent iodine deficiency....
scintillation crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
s, and had an angular resolution of 25 arcminutes. However, it stopped working shortly after the mission was launched.
Finally, the Pulsar X-2 telescope had 30 arcminute resolution and a 10 deg x 10 deg field of view, and operated in the energy range 2-25 keV.
Observations included studies of the Vela Pulsar
Vela Pulsar
The Vela Pulsar is a radio, optical, X-ray and gamma-emitting pulsar associated with Vela Supernova Remnant, in the constellation of Vela.- Supernova origins :...
, the Galactic Centre, Cygnus X-1
Cygnus X-1
Cygnus X-1 is a well-known galactic X-ray source in the constellation Cygnus. It was discovered in 1964 during a rocket flight and is one of the strongest X-ray sources seen from Earth, producing a peak X-ray flux density of 2.3 Wm−2Hz−1...
, Hercules X-1
Hercules X-1
Hercules X-1 , also known as 4U1656+35, is a moderately strong X-ray binary source first studied by the Uhuru satellite.It is composed of a neutron star accreting matter from a normal star probably due to Roche lobe overflow....
and the Crab Nebula
Crab Nebula
The Crab Nebula is a supernova remnant and pulsar wind nebula in the constellation of Taurus...
. The telescopes also measured the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
during peak solar activity.