|Nov 15, 1979
||Publication date of the first discoveries of X-ray emission from
`normal' hot (OB spectral-type) stars, by the Einstein Observatory
Imaging Proportional Counter (IPC) and High Resolution Imager (HRI);
the stars were members of the Cygnus OB2 Association and the Eta Carinae
Region: see Harnden et al., ApJ, 234, L51, 1979 and Seward et al. ApJ, 234,
L55, 1979, respectively, for more details.
Luminous OB star are now recognized to have (at least) two different types of
X-ray emission mechanisms: the more intense and hard X-ray emitters appear
to be all in binary systems where the winds of the two components are
colliding and producing shocked hot plasma, while the less bright soft X-ray
emitters are single stars in which self-shocking of the material outflowing
in their high-velocity winds generates the warm X-ray emitting plasma.
|20 Sep 1979
||Launch of the Third High Energy
Astrophysics Observatory (HEAO-3). This satellite conducted a
hard X-ray/gamma-ray survey of the sky with a high-resolution spectrometer
and also carried instrumentation to observe cosmic rays.
|11 Jul 1979
Skylab, the U.S.A.'s first space station, re-entered the
atmosphere, dispersing debris over an area stretching from the south-east
Indian Ocean to western Australia.
|9 Jul 1979
2 makes its closest approach (720,000 km or 10.11 Jupiter radii)
to the planet Jupiter before proceeding on to its next Grand Tour
rendezvous (with Saturn).
|19 Jun 1979
||Vela 5B ceases
||Prognoz 7 ceases
|2 Jun 1979
||Launch of Ariel
VI. This UK satellite carried 2 X-ray experiments as well as a
cosmic ray experiment. Unfortunately, its mission was subsequently
compromised by interference from ground-based radar which hampered pointing
operations, although it did make some useful science observations.
||First detection of X-ray emission from another planet in the Solar
System, namely Jupiter, by the Einstein Observatory:
see Metzger et al., JGR, 88, 7731, 1983 for further details. The emission was
hypothesized to be from energetic ions from abundant elements such as S and O
precipating out of the Io Plasma Torus into the strong Jovian magnetosphere.
In November 1999, Chandra observations of the Jupiter system detected
additional X-ray sources associated with some of the large moons (Io, Europa,
and possibly Ganymede) as well as with the Io Plasma Torus itself
(Elsner et al., ApJ, 572, 1077, 2002).
|9 Apr 1979
||The Third Small Astronomical
Satellite (SAS 3) ceases operation.
|5 Mar 1979
||Detection by 9 satellites carrying gamma-ray burst detectors of an
intense (peak flux of about 1.5 x 10-3
erg s-1 cm-2 in the 30 keV to 2 MeV band) and very
rapid (burst duration FWHM of 0.12 seconds) gamma-ray `spike' from
the direction of the supernova remnant N49 in the Large Magellanic Cloud. This
spike was followed by a slowly declining flux which was modulated by 8-second
pulsations for several minutes
afterwards. This object, now called SGR 0526-66, is
one of several known so-called Soft Gamma Repeaters (SGRs). SGRs
are believed by many (but not all) astronomers to be young neutron stars
with ultrastrong magnetic fields, otherwise known as magnetars. In the
4 years following this initial strong gamma-ray transient, 16 more (much
weaker) outbursts were seen from this source, but it has not been detected
since 1983. See Cline et al. (ApJ, 237, L1, 1980) for the initial
discovery paper on SGR 0526-66.
|5 Mar 1979
1 makes its closest approach (350,000 km or 4.89 Jupiter radii)
to the planet Jupiter before proceeding on to a flyby of Saturn.
|24 Feb 1979
||Launch of the US Air Force satellite
P 78-1. This satellite
carried a number of instruments, including a gamma-ray spectrometer,
an extreme-ultraviolet spectrometer, and an X-ray monitor.
|21 Feb 1979
||Launch of the first Japanese X-ray astronomy satellite
Hakucho, known as
CORSA-B prior to launch.
|9 Jan 1979
First High Energy Astrophysics Observatory (HEAO 1) ceases
|late Dec 1978
||Arrival of Venera 11
& 12 at Venus; landing units proceed to the Venusian surface
while the mother craft flies by the planet.
|13 Dec 1978
||Confirmation by the HEAO-1
A2 experiment that the peculiar emission-line
object SS 433 is a strong and variable X-ray source reported by
Marshall et al., IAU Circ. 3314, 1978: see also Marshall et al., ApJ, 230,
L145, 1979. Previous low spatial-resolution
observations by Ariel-V (Seward et al., MNRAS,
175, 39P, 1976) had discovered a variable X-ray source in this general
direction and, since SS 433 is near the center of the SNR W 50, the
authors speculated that it might be the stellar remnant of W 50, although
the optical counterpart of the X-ray source was not known.
SS 433 had been
discovered earlier in 1978 to be a strong, variable radio source, and
had been suggested as a possible X-ray emitter (Seaquist et al., IAU Circ.
3256, 1978). SS 433 went on to become one of the most well-studied objects
in the Galaxy: it is now generally believed to be an X-ray binary system
containing either a black hole or neutron star accreting from its
companion, and, at the same time, expelling material in two, high-speed
(0.26 times the speed of light) oppositely directed jets which precess with
a 164-day period. The variable Doppler shift of material in these jets was
later detected in the X-ray band, with first honors to EXOSAT (Watson et
al., MNRAS, 222, 261, 1986). It is also now commonly
believed that the compact object in SS 433 is the stellar remnant of
the supernova that created W 50.
|9 Dec 1978
||Arrival of the Pioneer Venus Multiprobe at Venus. All five probes
transmitted data while descending through the Venusian atmosphere
|4 Dec 1978
||Pioneer Venus Orbiter
arrives at Venus.
|13 Nov 1978
||Launch of the Second High
Energy Astrophysics Observatory (HEAO 2), renamed to the Einstein
Observatory once it successfully achieved orbit. Einstein went on
to become one of the most scientifically productive X-ray observatories
|31 Oct 1978
||The Seventh Interplanetary
Monitoring Platform (IMP 7) ceases operation.
|30 Oct 1978
||Launch of the joint French-Soviet SIGNE mission
Combined with the Venera
11 & 12 probes, this formed part of the first ever interplanetary
gamma-ray burst detection network, allowing accurate localization in the sky
of gamma-ray burst sources.
|15 Oct 1978
||The Eighth Orbiting Solar
Observatory (OSO 8) ceases operation.
|14 Sep 1978
||Launch of the
Venera 12 probe to Venus.
|9 Sep 1978
||Launch of the
Venera 11 probe to Venus.
|8 Aug 1978
||Launch of the Pioneer Venus Multiprobe.
||Launch of the Third
International Sun-Earth Explorer (ISEE-3). ISEE-3 was one
of a three part series of satellites to monitor solar wind and
interactions with the Earth and Sun. ISEE-3 was placed at the
Sun-Earth L5 point, roughly an hour upstream in the solar wind.
Among other instruments, ISEE-3 carries gamma-ray burst detectors.
|20 May 1978
||Launch of the Pioneer
Venus Orbiter (PVO), carrying (among many other instruments) a
gamma-ray burst detector. PVO completed the gamma-ray burst
(IPN) created by Helios-2 by supplying a 3rd mutually distant
|26 Jan 1978
||Launch of the NASA/ESA/UK SERC mission
Ultraviolet Explorer (IUE); this observatory performed
spectrophotometry of celestial objects with both high (0.1 - 0.3 Angstroms)
and low (6 - 7 Angstroms) spectral resolution at wavelengths between 1150
and 3200 Angstroms. IUE continued operating for two decades and became
the most successful ultraviolet observatory ever, revolutionizing our
understanding of the UV spectra of stars, galaxies, AGN, etc.
|5 Sep 1977
||Launch of NASA's Voyager 1
mission to Jupiter and Saturn on a Titan-Centaur rocket. Voyager 1
is still as of 2004 operational and became the most distant human-made
object in the universe in February 1998 when it passed Pioneer 10:
as of July 2004 it had reached a distance of 92 AU (13.8 billion km)
from the Sun and was believed to be in the vicinity of the solar wind
|20 Aug 1977
||Launch of NASA's Voyager 2
mission to Jupiter, Saturn, Uranus and Neptune on a Titan-Centaur rocket.
This mission is still operational and moving out of the solar system
and towards the interstellar medium at a speed of 3.3 AU per year:
as of July 2004 it had reached a distance of 74 AU (11.0 billion km)
from the Sun.
|12 Aug 1977
||Launch of the First High Energy
Astrophysics Observatory (HEAO 1).
||Solrad 11A ceases
|2 Feb 1977
||The Soviet space station
Salyut-4 performs a controlled re-entry into the Earth's
atmosphere over the Pacific Ocean.
||Solrad 11B ceases
|30 Jul 1976
||The Astronomische Nederlandse
Satelliet (ANS) ceases operation.
|20 Jul 1976
Viking 1 lander arrives at Utopia Plantia on Mars, the first
(soft) landing probe on the Martian surface.
|17 Apr 1976
||Helios 2 achieves its
perihelion distance of just 0.29 A.U.
|15 Mar 1976
||Launch of the paired satellites
Solrad 11 A & B.
Gamma-ray burst detectors were added to the Solrad 11 mission shortly
before launch after the realization of gamma-ray bursts seen by the
Vela series satellites.
||"First (interference) fringes" (the radio telescope equivalent of
"First Light" for an optical telescope) at the Very Large Array
(VLA) radio interferometer. The VLA is operated by the US National Radio Astronomy Observatory and is
situated on the plains of San Augustin near Datil, New Mexico.
|15 Jan 1976
||Launch of Helios
2 on a mission to explore the Sun and the solar wind environment
in the near-solar (within the orbit of Mercury) region. Helios-2 was the
first spacecraft to be launched with a detector designed specifically for
gamma-ray bursts. Its launch initiated the first gamma-ray burst
with Ariel-5 and the Vela spacecraft already in orbit. The launches of
Pioneer-Venus Orbiter (PVO) and of Veneras-11 and
Veneras-12 in 1978 finally completed the fully
interplanetary array with 3 or more mutually distant vertices.
|Late Oct 1975
||First X-ray detection of Beta Persei or Algol, the prototype of
the 'semi-detached' class of mass-transfer binary systems in which one
star fills (and overflows) its Roche Lobe, after two
previous unsuccessful attempts, by the Rotational Modulation Collimator
instrument onboard the Third Small
Astronomical Satellite (SAS 3). See Schnopper et al. 1976, ApJ,
210, L75 for more details. The X-ray emission from systems like Algol
is now thought to be a result of the rapid and synchronized rotation
of the Roche Lobe-filling component and not to be directly related to
the mass transfer process.
|14 Aug 1975
||Peak of the X-ray outburst of A 0620-00 (also known as Nova Mon
1975), arguably the brightest non-solar X-ray source yet detected
in terms of its observed flux, which exceeded the flux of Sco X-1, the
brightest persistent X-ray source in the sky, by a factor of 3. This outburst
was detected by the Sky Survey Experiment on the Ariel-V satellite.
The inferred peak X-ray luminosity of this black hole binary system was
1038 erg s-1, 20 million times brighter than its
quiescent level. See Elvis et al. 1975, Nature, 257, 656 et seq. for the
discovery papers, and Chen et al. 1997, ApJ, 491, 312 for a review of the
class of Soft X-ray Transients or X-Ray Novae to which A 0620-00 belongs.
|9 Aug 1975
||Launch of the European COS-B
|21 & 22 Jul 1975
||First detections of any extra-solar system objects in the extreme
ultraviolet (EUV) region (wavelengths from 100 to 1000 Angstroms
or photon energies from 0.012 to 0.12 keV), namely the hot white dwarf
stars Feige 24 and HZ 43, by the
Apollo-Soyuz Test Project (ASTP) Extreme-Ultraviolet (EUV)
Telescope. The column density and hence optical depth of the
interstellar medium had been generally expected to be so high that
few, if any, objects would be detectable in the EUV range, but the
detections of HZ 43, a previously known soft X-ray source, and Feige 24
showed this to be incorrect. The EUV and soft X-ray emission from hot
white dwarfs is `photospheric' in origin, i.e., the lack of significant
opacity due to metals and Helium means that the EUV optical depth unity
surface or photosphere is much deeper in the star than the visible light
photosphere is. See Lampton et al. (ApJ, 203, L71, 1976) and
Margon et al. (ApJ, 210, L79,1976) for more details.
|15 Jul 1975
||Launch of the Apollo spacecraft which became part of the Apollo-Soyuz
Test Project (ASTP), the first joint U.S.-Soviet space mission.
|21 Jun 1975
||Launch of the Eighth Orbiting
Solar Observatory 8 (OSO 8).
|7 May 1975
||Launch of the Third Small
Astronomical Satellite (SAS 3).
| 8 Jan 1975 at 1:18 UT
||First detection of an X-ray flare simultaneously with an optical flare
from an M dwarf star, namely the flare star UV Cet (L 726-8 AB), by the
Utrecht soft-energy (0.2 - 0.28 keV) energy detector on the
Astronomical Netherlands Satellite
(ANS): see Heise et al. (ApJ, 202, L73, 1975) for more details.
Web page author: Stephen A. Drake (based on an original by Jesse S. Allen)