Commission 41 is one of the largest specialist components of the IAU. At the General Assembly in 1982 at Patras the number of ordinary members was increased from 79 to 86 as a testimony to the growing interest among astronomers in the history of their subject. At the same time the number of consulting members rose from 32 to 40, which shows that an increasing number of highly competent historians of science is engaged in research in the history of astronomy without being professional astronomers. However, many valuable contributions to the subject come from historians who are not members. In consequence, the principal purpose of Commission 41 is to serve as a link between all historians of astronomy whether they be members or not, by initiating research into particular areas, by disseminating new results, or simply by creating possibilities of personal contacts between scholars from different parts of the world. This is mainly achieved by meetings of various kinds.

Research on close binary systems has continued at a high level during the past triennium, although the rate of growth is noticeably slower – probably reflecting the cutbacks in funds to which many of us are subject. There have also been changes of emphasis within the field, which are commented on in the pages that follow. These reflect both changing opportunities for observation and the natural development of the subject. In many areas, the time is ripe for a more critical look at ideas that previously seemed adequate.

A rapid and dramatic change in our views of the Universe which we have witnessed during the past two decades or so is often compared with what happened at the time of Galileo. Revolutionary role of the optical telescope then may be analogized with that of space-astronomy today which has drastically opened the new observational window to the Universe. The revolution is ongoing with a rapid pace or even being accelerated.

The period leading up to the last IAU General Assembly was dominated in X-ray Astronomy by the results from the Einstein Observatory. This first application of a large, satellite-borne, high resolution X-ray telescope to the study of cosmic sources had led, by the end of orbital operation in April 1981, to the detection of X-ray fluxes from a wide variety of astronomical objects and the full maturing of X-ray Astronomy. During the past three years a strong scientific output has continued to flow from the analysis of the more than 5600 separate Einstein observations, many of which are now widely available via the Einstein Data Bank. In sharp contrast, the peak of activity and scientific output from Einstein will apparently be followed, in the United States, by almost a decade with no new X-ray satellite. Fortunately, successful launches have been achieved in both the Japanese and European programmes, with Tenma launched in February 1983 (to join Hakucho in orbit) followed by EXOSAT three months later. Both these new missions have attracted world-wide interest and observing time on both is at a premium. Of a range of instruments on board the Tenma satellite the most productive is proving to be the large (~800 cm2) array of gas scintillation proportional counters. These detectors, flown for the first time on Tenma (and EXOSAT), provide a factor-of-two increase in spectral resolution over the more conventional proportional counters, an advantage which is particularly valuable in resolving the key emission line and absorption features associated with the K-shell of iron, near ~7 keV. One particularly exciting result reported from this Tenma instrument was an apparent absorption feature at ~4.1 keV in X-ray burst spectra from the source 2S 1636-536 (later supported by EXOSAT observations), the feature being attributed to red-shifted iron absorption in the strong gravitational field close to the neutron star burst source! At the time of writing (December 1984) a power storage problem is limiting the operational efficiency of Tenma, but the scientific payload continues to function well.

During 1982-1984, progress in ultraviolet astronomy continued through extensive observations with the International Ultraviolet Explorer (IUE), continuing programs of sounding rocket and balloon flights, and through observations made from other orbital spacecraft, including the Space Shuttle and ASTRON. In addition, there was important progress in the design and development of facilities for future missions, including the Hubble Space Telescope.

During this reporting period, the satellites ISEE 3 (now ICE), IMP 8, Helios I, Hinotori, Nimbus 7 (ERB), P78-1, Pioneer Venus Orbiter (PVO), Spacelab 1 and Solar Maximum Mission (SMM) continue to provide solar observations. We review briefly some recent developments, selected by the author as most significant, concerning: coronal mass ejecta, high-energy neutral emissions, X-ray and microwave bursts, the solar constant, and solar flare periodicity. While the emphasis is on new work, some significant results, obtained in earlier spacecraft experiments and only recently reported, are also mentioned. The repair, in space, of SMM in 1984 April, resulting in reactivation of three of the four pointed experiments is briefly described and a status report of the SMM 2 mission is given. We conclude with a summary of important future programs.

Solar system objects may be studied in space by two general techniques. Everyone is familiar with the exciting aspects of deep space probes: very high spatial resolution; in situ measurements of particles and fields; in situ chemistry studies by mass spectrographs and gas chromatographs; unique phase angle and occultation opportunities. However, the Solar system can also be studied to great advantage by observatories in orbit around the Earth. The broader spectral range available above the terrestrial atmosphere is as important for planetary studies as it is for investigations of more distant astronomical targets. Both techniques will be discussed in this brief report.

During the report period (1982–1984) several symposia, colloquia, and workshops in the field of stellar classification were held. These include: IAU Symposium No. 111 ”Calibration of Fundamental Stellar Quantities” (Como, May 24 29, 1984, ed. D. S. Hayes et al.), IAU Colloquium No. 76 “The Nearby Stars and the Stellar Luminosity Function” (Middletown, June 13-16, 1983, ed. A. G. Davis Philip and A. R. Upgren), IAU Colloquium No. 78 “Astronomy with Schmidt-Type Telescopes” (Asiago, August 30-September 2, 1983, ed. M. Capaccioli), the workshop “The MK Process and Stellar Classification” (Toronto, June 6-10, 1983, ed. R. F. Garrison), the Colloquium ”Cool Stars with Excess of Heavy Elements” (Strasbourg, July 3-6, 1984).

The program has been continued thanks to the financial help of IAU, Unesco, and of local authorities. A school has been held in Lembang, Indonesia from May 16 to June 2, 1983, with students from India, Indonesia, Malaysia, Philippines, and Thailand. The Local Organizing Committee, chaired by B. Hidayat was very efficient, and the school is considered to be one of the most successful held to date. Both teachers and students expressed their appreciation to the School Secretary, Dr J. Kleczek, and to the IAU Executive Committee. Another school, foreseen in Venezuela for September 1983, had to be cancelled due to the lack of support of the Venezuelan Research Council. There are plans to hold several schools during the 1985-1988 period.

The preparation of a report dealing with such a large domain is almost an impossible task. Because so many different questions, problems and expertises are assembled under the word “Cosmology”, my approach has been the following: first to divide this field in a somewhat arbitrary fashion into the following sections: very early universe – elementary particle and cosmology – early nucleosynthesiscosmological parameters (Hubble constant, deceleration parameter, cosmological constant) – large scale structures, intergalactic gas, missing mass – clusters of galaxies and intercluster gas – anisotropy of the black body radiation – formation of galaxies – quasars and their evolution – cosmological evolution of radiosources. I have then asked to the most knowledgeable specialists to review briefly each of these most important questions on which many excitinq and very new results have been obtained not only by the astrophysicists themselves but also by particle physicists, nuclear physicists, theoretical physicists, … This is why the reader will read in section 1 the report on primordial nucleosynthesis written by G. Steigman, in section 2 Anisotropy of the black body radiation by D.T. Wilkinson and E. Meichiorri, in section 3 Clusters of galaxies by 3. Einasto, in section 4 Galaxy formation by B.J.T. Jones, in section 5 Quasars and their evolution by M. Schmidt and in section 6 the Cosmological evolution of radio sources by R.A. Windhorst. Let me thank these colleagues for their excellent work in writing these various reviews.

The 2.7 K microwave background radiation provides a sensitive probe of the universe in the interesting, but poorly understood, epoch around z ˜ 1000. At this time (age ~ 10 yr) the universe has cooled to T ~ 4000 K, the plasma combines, Thomson scattering ceases, and matter and blackbody radiation decouple. Subsequently, the radiation freely propagates to us, carrying the imprint of temperature fluctuations on the z ~ 1000 surface. The temperature fluctuations could have been caused by primordial density fluctuations, anisotropy in the expansion of the universe, or inhomogeneity in the initial temperature distribution; the z = 1000 surface we see was not causally connected at the time the radiation was released. Interpretation of the anisotropy measurements is complicated by the possibility that the matter may have been reionized (e.g. by massive stars), so the radiation may have been rescattered, possibly as late as z ~ 7.

Abell and Corwin (34.160.040) have continued the search of southern clusters on photographs taken with the U.K. Schmidt telescope at Siding Spring. A catalogue is in preparation, it continues the Abell catalogue toward southern declinations. West (32.160.019, 32.160.036, 34.160.044) has initiated a study of distant southern clusters with automatic identification of clusters and objective evaluation of their properties. Noonan (30.160.006) and Sarazin et al. (31.160.030) have listed clusters with published redshifts. Numerical simulations have demonstrated the presence of bias in observed clusters as difined by Abell (33.160.006), ranked absolute magnitudes of galaxies are distance dependent (33.160.081), some clusters may be due to projection effects (34.160.009).

This article surveys the literature from July 1981 to June 1984. It is neither possible nor desirable to refer to all papers on the subject, and accordingly only papers that are generally representative of some particular idea are explicitly mentioned. Galaxy Formation by its very nature has considerable overlap with other areas of cosmology such as the anisotropy of the cosmic background radiation, the question of the mass density of the universe, the nature of the large scale clustering, and detailed observations of galaxies. These are all topics covered by other reports to Commission 47 and the reader will therefore find only scant attention paid here to these important subjects.

In the past three years several surveys of optically selected quasars have been published. The Palomar Bright Quasar Survey (Schmift & Green 1983) covers 10,714 deg to a limiting magnitude varyinq with position in the sky, with an effective limiting magnitude B = 16.16. The survey lists 114 objects of which 92 are quasars with Mg < −23. All objects have redshifts less than 2.15 as they were selected for ultraviolet excess. Marshall et al. (1983) have extended the spectroscopic coverage of objects in the Braccesi field (AB) to B = 18.25. They also report first results in the deep Braccesi field (BF) to B = 19.2. Koo (1983) reports on a photometric and spectroscopic survey of quasars to B = 22.5 (see also Koo & Kron [1982]). The present state of quasar surveys is critically discussed by Smith (1983) in a very useful review.

Considerable progress has been made over the last few years in the study of the cosmologica! evolution of radio sources, both regarding the collection of deeper and higher quality observations and towards a better understanding of the physical processes that may cause the epoch dependent properties of the radio source populations on cosmological timescales. In this review it is attempted to give a fair coverage to the work of all groups that made relevant contributions to this field since 1981. A few very important papers from before 1980, that were not dealt with by the previous IAD commission, are covered as well. For more detailed reviews we refer to Katgert (1980), Kellerman (1980), van der Laan and Windhorst (1982), van der Laan et al. (1983), Longair (1978), Wall and Benn (1982), Wall (1983) and Windhorst (1984). Le latter review is a more detailed version of the current report to IAU commission 47 on Cosmology.

In view of the broad range of topics covered by Commission 48 and the consequent inevitable overlap with other commissions, it is not feasible to produce a comprehensive self-contained report. The commission therefore restricts its report to a selected list of accessible recent review articles and conference reports, where up-to-date summaries of various topics can be found. Such a list is given below.

The Commission is intended to study the origin of the solar wind, the heliosphere, i.e., the region dominated by the supersonic solar wind, and the heliospheric interface with the interstellar medium. The activities of the Commission cover both theoretical and observational aspects of these three regions.

While a number of site testing campaigns are in progress throughout the world, the dominant efforts seem to be associated with plans for very large telescopes. These plans, improved telescope technology, and the realization that astronomical observations from space will put increasing demands on ground-based observing facilities have given new impetus to site identification and to the optimum utilization of existing sites. A most excellent review of the factors involved in site identification is now available in the Proceedings of the ESO Workshop on Site Testing for Future Large Telescopes, edited by A. Ardeberg and L. Woltjer 1981. These Proceedings and Woolf’s review (1982, Ann. Rev. Astron. Astrophys. 20 367) provide a solid background of current site evaluation factors.

The possibility that life, primitive or advanced, might exist in other places of the Universe has occupied the minds of scientists and lay-people for thousands of years. It is only in the last 25 years, however, that we have finally begun to search for answers to this profound question using experimental techniques. The goal of Astronomy is to understand the origin and evolution of planets, stars, galaxies and of the Universe as a whole. The appearance of life is an integral part of this whole process and our picture of the Universe will never be complete until we will comprehend also the significance of life in the process of Cosmic Evolution.

Since the last General Assembly in Patras, Greece, we have held three meetings of the Working Group. The 10th Meeting was held in Mzkheta, the ancient capital of Georgia, USSR, hosted by their Academy of Sciences on April 3-7, 1984. All members except one, who was represented by a member of his Task Group, were present at the very productive meeting.