A Brief History of High-Energy Astronomy: 1990 - 1994


In Reverse Chronological Order

Nov 1, 1994 Launch of GGS-WIND carrying the Transient Gamma Ray Spectrometer (TGRS) and the Konus gamma-ray burst instrument (still operational).
Oct 11, 1994 Termination of the Magellan mission to Venus when the spacecraft entered the Venusian atmosphere; the primary goal of this mission was to make the most highly detailed maps of this planet ever using a sophisticated imaging radar.
Jul 16 - 22 1994 Detection of X-rays triggered by the impact on the planet Jupiter of fragments of Comet Shoemaker/Levy 9 by the ROSAT HRI instrument. Unlike in the optical and infrared where the brightenings occurred at the impact site in Jupiter's southern hemisphere, the X-ray brightenings occurred in Jupiter's auroral regions in its high northern latitudes, for reasons which are still not completely understood. See Waite et al. (1995, Science, 268, 1598) for more details about this observation.
Dec 23, 1993 End of scientific operations of the COsmic Background Explorer (COBE), a NASA mission whose primary goals were to study the spectrum and anisotropy of the cosmic 3 degree K background in the energy band from 0.1 to 10 mm, and the spectrum and angular distribution of the diffuse infrared background in the IR and far-IR bands (1 to 300 microns).
Aug 21, 1993 Destruction by an explosion in the rocket propulsion system of Mars Observer as it attempted to maneuver into a Martian orbit. It is the first interplanetary probe lost by NASA. Lost with it is the onboard gamma-ray burst (GRB) detector that had formed part of the interplanetary GRB detector network consisting of Mars Observer, the Compton Gamma Ray Observatory, and the Ulysses solar probe.
Jun 23, 1993 Recovery of the European Retrievable Carrier (EURECA) free-flyer by the Space Shuttle Endeavor (STS-57) after it had spent almost 11 months in low-Earth orbit (LEO). The EURECA satellite carried a number of experiments designed to conduct microgravity studies, solar observations, and material technology investigations. Also on board was the WATCH or Wide Angle Telescope for Cosmic Hard X-rays instrument which gradually scanned across most of the sky during its mission lifetime.
Apr 25, 1993 Launch of the Array of Low Energy X-ray Imaging Systems (ALEXIS) satellite. This US Department of Energy (DOE) mini-satellite contains six compact normal-incidence ultrasoft X-ray or extreme-ultraviolet (EUV) telescopes operating in narrow bands centered on energies of 0.066, 0.071, and 0.095 keV (still operational).
Mar 28, 1993 Discovery of the Supernova 1993J in the Messier 81 Galaxy, the second brightest supernova observed in the twentieth century. This Type IIb supernova had a prompt peak in its optical brightness on March 30, followed by a rapid decline, and then a gradual rise to a second peak on April 18. It was detected as an X-ray source by the ROSAT X-ray Observatory in an initial observation on April 3, and follow-up observations by the ROSAT and ASCA satellites showed a slow and steady decline in its X-ray flux over the next year or so. SN 1993J was also detected as a soft gamma-ray (50 - 150 keV) source by the Compton Observatory OSSE instrument 12 days and then 1 month after its discovery. See the papers by Zimmermann et al. (Nature, 367, 621, 1994), Uno et al. (ApJ, 565, 419, 2002) and Leising et al. (ApJ, 431, L95) on the ROSAT, ASCA, and OSSE observations, respectively.
Feb 20, 1993 Launch of the fourth Japanese X-ray astronomy satellite, Advanced Satellite for Cosmology and Astrophysics (ASCA), known as Astro-D prior to its launch.
Jan 31, 1993 Detection of an intense gamma-ray burst (GRB) by the instruments on the Compton Gamma-Ray Observatory (CGRO) at 18:57:12 UT. This GRB was arguably the brightest GRB observed by CGRO, with a peak flux of 105 photons s-1 cm-2. Because the date on which it occurred was also that of the Superbowl, this GRB has become known (at least in the US) as the `Superbowl Burst' since it occurred on the same day as the 1993 National Football League Superbowl.
Oct 8, 1992 Pioneer Venus Orbiter enters the Venusian atmosphere. At the time of its demise, the Orbiter had been a functioning anchor in various interplanetary gamma-ray burst detection networks for over 14 years.
Sep 25, 1992 Launch of NASA's ill-fated Mars Observer spacecraft.
Aug 2, 1992 Release of ESA's European Retrievable Carrier (EURECA) free-flying satellite from the Space Shuttle Atlantis (STS-46).
Jul 1992 The Gamma satellite ceases operations. This Soviet-led mission had as its principal instrument the Gamma-1 telescope, a gamma-ray detector sensitive to gamma-rays with energies from 50 MeV to 6 GeV.
Jun 7, 1992 Launch of NASA's Extreme UltraViolet Explorer (EUVE).
May 21 & 28, 1992 Publication dates of the discovery of soft X-ray pulsations from the hithertoo mysterious gamma-ray source called Geminga by Halpern and Holt (Nature, 357, 222, 1992), based on ROSAT observations, and of gamma-ray pulsations from the same source by Bertsch et al. (Nature, 357, 306, 1992), based on CGRO EGRET observations. Geminga (aka 2CG 195+04) was the second brightest gamma-ray source in the >=100 MeV band that had been detected by the COS-B satellite, but its nature had remained unclear until this discovery of 237 millisecond pulsations confirmed some previous suggestions that it was, like Vela, a gamma-ray pulsar.
Late 1991/Early 1992 Definitive detection of soft (0.5-2.0 keV) X-ray emission from the supernova SN 1987A, by the imaging ROSAT PSPC detector. Earlier observations by the (non-imaging) Ginga LAC detectors had suggested the existence of a soft X-ray (in addition to hard X-ray) emission, but an earlier short ROSAT observation in Jun 1990 had failed to detect any such emission at the position of the supernova. This soft X-ray emission is believed to be qualitatively different than the hard X-ray emission (produced by Compton downscattering of the Cobalt 56 gamma-ray emission lines) and to be due to thermal emission by plasma in the pre-existing circumstellar material which is being shock-heated by the supernova blast wave. See Gorenstein et al. (ApJ, 420, L25, 1994) and Beuermann et al. (A&A, 281, L45, 1994) for more details.
Nov 1, 1991 Ginga, the third Japanese X-ray astronomy satellite (ASTRO-C), ceases operation.
Oct 15, 1991 Detection of a cosmic ray particle (or, less likely, a gamma-ray photon or a strangelet) with the highest ever recorded energy of 3.2 x 1020 eV (or 5 x 108 erg, equivalent to the kinetic energy of a 1 kilogram rock moving at a speed of 10 meters per second!) by the University of Utah's Fly's Eye I fluorescence detector. Because of its high energy and the effect of the cosmic microwave background radiation on such an energetic particle (the `Greisen-Zatsepin-Kuzmin or GZK Cut-off'), if this event were due to a cosmic ray, it must have originated from a source no more than 30 Megaparsecs distant. See Bird et al. (ApJ, 441, 144, 1995) for a detailed report on this event and O'Halloran et al. (Physics Today, January 1998, p. 31) for a review of the highest energy cosmic rays and other references. The physics of cosmic rays is discussed at a popular level at the Cosmic and Heliospheric Learning Center.
Apr 21, 1991 Detection of a short burst of gamma-rays from the direction of the Earth, by the BATSE instrument on board the Compton Gamma Ray Observatory (CGRO): see Fishman et al. (Science, 264, 1313, 1994) for more details. This was the first of 75 so-called Terrestrial Gamma Flashes (TGFs) discovered by CGRO; they are generally believed to be emission from highly relativistic electrons generated by strong electric fields in the Earth's mesosphere associated with thunderstorms, although alternate suggestions have been proposed, e.g., that they are due to ultra-high-energy neutrinos which have passed through the Earth and then interacted with the atmosphere to produce upward-directed air showers (see Fargion, ApJ, 570, 909, 2002).
Apr 5, 1991 Deployment of NASA's Compton Gamma-Ray Observatory (CGRO) by the Space Shuttle Atlantis (STS-37).
Mar 30, 1991 First Detection of X-Ray emission close to the peak of a classical nova outburst, by the ROSAT Position Sensitive Proportional Counter (PSPC). Nova Herculis 1991 was discovered by optical observers on 1991 March 24-25 near or just after its 5th magnitude maximum. It was observed by ROSAT five days later, and detected as a `hard' X-ray source with an inferred temperature of >=108K interpreted to be due to shocked circumstellar material. See Lloyd et al. (Nature, 356, 222, 1992) for more details about this discovery.
Dec 2, 1990 Launch of the Space Shuttle Columbia (STS-35) carrying the Astro 1 payload. Astro 1 included three UV telescopes (UIT, HUT, & WUPPE) and the Broad Band X-Ray Telescope (BBXRT).
Nov 1990 Establishment of the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA's Goddard Space Flight Center (GSFC).
Oct 6, 1990 Launch of the joint NASA/ESA Ulysses mission, from the Space Shuttle Discovery (STS-41). This satellite carries a solar X-ray and cosmic gamma-ray burst experiment. (still operational).
Jul 11, 1990 Launch of the Russian Gamma satellite. This Soviet-led mission had as its principal instrument the Gamma-1 telescope, a gamma-ray detector sensitive to gamma-rays with energies from 50 MeV to 6 GeV.
Jun 29, 1990 Detection by the Röntgen Satellit (ROSAT) of X-ray emission from the Moon. This was the first X-ray detection of the Moon by a satellite in Earth orbit (X-rays had previously been detected by detectors on Apollo spacecraft while in lunar orbit), and the implied X-ray luminosity of 7 x 1011 erg s-1 was 1015 times smaller than that of the Sun. The X-rays were interpreted as being due to back-scattering of solar X-rays (see Schmitt et al. 1991, Nature, 349, 583 for more details). Interestingly, the modern age of X-ray astronomy began in a flight made 28 years previous to this on Jun 18 1962 whose (unsuccessful) aim was to detect such scattered solar X-rays from the Moon (it instead detected the first extrasolar X-ray source, Sco X-1, and the X-ray background).
Jun 1, 1990 Launch of Röntgen Satellit (ROSAT), an X-ray and EUV astronomy mission due to an international collaboration between Germany, the UK, and the US. This mission had two phases, an All-Sky Survey phase from the end of July 1990 until February 1991 in which the spinning satellite mapped the entire sky in both X-rays and the EUV (and detected more than 100,000 discrete X-ray sources), and a pointed observation phase in which the satellite could make deep observations of selected positions in the sky.
Apr 18, 1990 Launch of the Hubble Space Telescope (HST). The HST is a 2.4-meter reflecting telescope which was deployed in low-Earth orbit (600 kilometers above the surface of the Earth) by the crew of the space shuttle Discovery in mission STS-31 on 25 April 1990. HST's instruments have been serviced and/or replaced several times and can observe in the ultraviolet, visible light, and near-infrared spectral regions. (still operational).


Acknowledgements

We would like to thank the following individuals for their contributions to this page: Jesse S. Allen, and Ian M. George along with JPL's Space Calendar and the Working Group for the History of Astronomy's Astronomiae Historia (History of Astronomy) information pages.

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Web page author: Stephen A. Drake (based on an original by Jesse S. Allen)

Web page maintainer: Stephen A. Drake



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