The HEAO-2 Observatory or the Einstein Observatory is the world's first orbital observatory with mirrors that can focus X-rays . The principle of operation of the observatory mirrors is based on the gliding reflection of x-ray photons incident on the telescope aperture. Before the launch, the observatory was called HEAO-B, after the successful start of the operation, the observatory was renamed the Einstein name observatory. The observatory was launched from Cape Canaveral , Florida, USA on an Atlas rocket with an upper stage Centaurus SLV-3D. The height of the orbit of the observatory was about 500 km, the inclination was about 23.5 degrees.
| HEAO 2 (High Energy Astronomy Observatory) | |
|---|---|
 HEAO2 / Observatory them. Einstein | |
| Organization |  NASA |
| Prime contractors | TRW Inc. |
| Wave band | X-rays (0.2–20 keV ) |
| NSSDC ID | 1978-103A |
| Location | geocentric orbit |
| Orbit type | low booty |
| Orbit height | ~ 500 km |
| Period of treatment | 93 minutes |
| Launch date | November 13, 1978 05:24 UTC |
| Launch location | Cape Canaveral |
| Means of putting into orbit | Atlas |
| Duration | 3 years (until April 1981) |
| Date of detour | March 25, 1982 |
| Weight | 3130 kg |
| Type of telescope | spectrometers |
| Scientific instruments | |
| microchannel camera |
| proportional position-sensitive meter |
| spectrometer |
| Bragg spectrometer |
| proportional counter |
| diffraction spectrometer |
| Site | heasarc.gsfc.nasa.gov/do ... |
Tools
The observatory carried one X-ray telescope (focusing X-rays due to their reflection at sliding angles) with an effective area of about 400 sq. Cm on energy 0.25 keV with a decrease to ~ 30 sq. Cm on energy 4 keV. The following tools were installed in the focal plane of the telescope.
HRI
HRI (High Resolution Imaging camera) is a position-sensitive high-resolution camera, the working energy range is 0.13-3.5 keV.
The instrument did not have its own spectral resolution, but could be used in conjunction with a diffraction grating (OGS). In this configuration, the tool made it possible to achieve a record for that time energy resolution of 10-50 in a relatively wide energy band. Due to the general principle of operation of the instrument, its quantum efficiency was small - the effective area of the instrument was only 10–20 sq. Cm at energies below 1 keV and 5 sq. Cm. at an energy of 2 keV.
However, the angular resolution of the instrument made it possible to fully use the capabilities of the focusing optics of the observatory - within 5 angular minutes from the axis of the telescope’s field of view, the angular resolution of the instrument was about 2 arc seconds (depended only on the quality of the x-ray optics). Such an angular resolution remained record-high until the Chandra Observatory was launched into orbit in 1999.
Measurements of the positions and morphology of a large number of X-ray sources both in our Galaxy and outside of our Galaxy led to a huge leap in understanding the nature of various X-ray objects.
IPC
IPC (Imaging Proportional Counter) - proportional counter, positionally sensitive, working range of energies 0.4-4 keV various sky surveys, including deep ones, with sensitivities up to 10 −14 erg / s / cm 2. The effective area of the instrument was about 100 sq. Cm, the angular resolution of about 1 angle. minutes
In combination with the HRI instrument, X-ray sky surveys conducted with the IPC instrument gave the first observational facts about the populations of accreting black holes in the centers of galaxies. One of the most important observations of the IPC and HRI instruments is the following - it was first shown that the cosmic X-ray background, already detected by the first X-ray instruments, is created by the total radiation of a huge number of extragalactic sources, mainly active galactic nuclei [2]
SSS
SSS (Solid State Spectrometer) - solid - state spectrometer (lithium-drifted Si (Li)), operating energy range 0.5-4.5 keV. The detector covered a size of about 5 angles of minutes and was not located exactly at the focus of the x-ray telescope (the image of the sources on the detector was about 1 angles of a minute). The working temperature of the detector was about 100 K, which led to ice freezing on its surface and, therefore, impaired sensitivity in the soft X-ray range. Periodically, before a long series of observations, the detector was heated to a temperature of 220K, which made it possible to reduce the amount of ice on the detector. After 9 months of periodic defrosting of the detector, it was possible to almost completely get rid of ice. Despite this, a model for changing the response function as a function of time was constructed for the detector, which made it possible to have sufficiently accurate calibration data for any observation point. In October 1979 (between October 3 and 13), in accordance with the calculations, the cryogenic cooling system of the detector exhausted the coolant reserves, which led to the failure of the instrument. With a significant effective area (about 200 sq. Cm), the SSS instrument had a record energy resolution of 160 eV in the energy range of 0.3–4 keV. The next step in improving the energy resolution of X-ray instruments was only possible at the Japanese observatory ASKA , launched in 1993.
FPCS
FPCS (Bragg Focal Plane Crystal Spectrometer) - Bregg crystal focal spectrometer The spectrometer consisted of 6 different diffractor crystals. The spectrometer had the opportunity to observe through 4 different fields of view 1´ x 20´, 2´ x 20´, 3´ x 30´ and through a round field of view with a diameter of 6´. In real observations, only the last three were used. The effective area of the spectrometer ranged from 0.1 to 1 sq. Cm. with an energy resolution of E / dE = 50-1000. In each specific observation of the spectrometer, the spectrum was measured only in a fairly narrow energy band — about 20–80 eV. As a result of observations, high-resolution spectra were obtained from more than 40 sources [3]
OGS
OGS (Objective grating spectrometer) - Spectrometer on a diffraction grating. He worked in conjunction with the position-sensitive camera HRI.
MPC
Separately from the focusing telescope, a proportional MPC counter (Monitor Proportional Counter) was installed; the working energy range was 1–20 keV.
The MPC gas proportional meter was filled with a mixture of argon and carbon dioxide. It had a circular field of view, bounded by a collimator with a size of 1.5 degrees (width at half-height), the optical axis of which was aligned with the optical axis of the observatory X-ray telescope. The 1.5 millimeter beryllium window was the cover of the gas volume and at the same time protected the gas meter from the photons of the ultraviolet range. The effective detector area is 667 sq. Cm. The photon energy detected by the instrument was digitized into one of 8 channels, the width of which increased logarithmically from 0.4 keV at the lower edge of the working range of the device to 6.7 keV at the upper edge. The energy resolution of the device was 20% at 6 keV energy. The tool worked from November 19, 1978 until April 1981, except for the 3-month period between August 27, 1980 and December 8, 1980. During this period, the tool was turned off due to problems with the orientation of the spacecraft.
See also
- HEAO-1
- List of spacecraft with x-ray and gamma detectors on board