The IAU Working Group on Historical Radio Astronomy (WGHRA) was formed at the 2003 General Assembly of the IAU as a Joint Working Group of Commissions 40 (Radio Astronomy) and 41 (History of Astronomy), in order to: a) assemble a master list of surviving historically-significant radio telescopes and associated instrumentation found worldwide; b) document the technical specifications and scientific achievements of these instruments; c) maintain an on-going bibliography of publications on the history of radio astronomy; and d) monitor other developments relating to the history of radio astronomy (including the deaths of pioneering radio astronomers).

Division X provides a common theme for astronomers using radio techniques to study a vast range of phenomena in the Universe, from exploring the Earth's ionosphere or making radar measurements in the Solar System, via mapping the distribution of gas and molecules in our own Galaxy and in other galaxies, to study the vast explosive processes in radio galaxies and QSOs and the faint afterglow of the Big Bang itself.

There have been important advances in radio astronomy in the last three years. New discoveries both at the galactic and extragalactic scale have been reported over this period and we highlight here several of them. The outstanding results of the Wilkinson Microwave Anisotropy Probe satellite, allowing an accurate determination of the main cosmological constants, are certainly among the most important. At the international level, the consolidation of the Atacama Large Millimeter Array project, with participation of the USA, Europe, and Japan and an estimated cost of around one billion US dollars, takes the construction of radio telescopes to a new level of complexity and potential. We also include the Progress Report of the Working Group on Historic Radio Astronomy, that includes a description of the duties and activities of this recently created working group.

A rotating gas disk was discovered around a T-Tauri star, GG-Tau, in Taurus by using the Nobeyama Millimeter Array (NMA) (Kawabe et al. 1993). To analyze the observed data, we have numerically calculated velocity profiles of CO emitted from protoplanetary gas disks by taking account of the line radiative transfer.

We made aperture masking optical interferometry experiments using up to 30 apertures and with a tip-tilt correction of wavefront error. We examined the performance of minimum redundant configurations of 11–30 sub-apertures on the pupil plane mask. These configurations have two advantages; the redundancy noise is as small as realized in non-redundant masking method, and the uv-coverage is as high as in speckle interferometry enabling to get reconstructed images without mask exchange. We also examined the effect of tip-tilt wavefront correction within a telescope pupil in front of the aperture masking optics. The light coherency between sub-apertures was shown to increase by the correction.

A high-spatial-resolution observation of the NGC 7538 molecular cloud core has been performed with the Nobeyama Millimeter Array. We report on the detailed structure of the region including IRS1-3 complex and IRS11 based on the CS J = 1−0 line observational results.

The observation was done in December, 1988. The field center was at R.A. (1950)=23h11m36.8s, Dec (1950)=61° 11′ 10″ which is between IRS1-3 complex and IRS11. The primary beam, 2.5’(FWHM), was large enough to cover both IRS1-3 complex and IRS11. We used 18 baselines, and the synthesized beam became 10.6″×10.4″ (natural weight).

Molecular clouds in the Galactic center region are distributed mainly along the Galactic plane and have filamentary shapes with several clumps (Bally et al. 1987, Tsuboi et al. 1989). The “50-km.s−1 molecular cloud (M-0.02-0.07)”, which is located ~3’ east from Sgr A West, is one of most remarkable clumps on these molecular filaments. The intimate relation between this cloud and Sgr A East has been mentioned by many authers (e.g. Ho et al. 1986). Several compact HII regions are located toward the cloud (Ekers et al. 1983). The recombination line velocities correspond to the molecular line velocities in the cloud (Goss et al. 1987). Thus this cloud is one of active star forming regions near the Galactic center.

We observed the 50-km-s−1 molecular cloud in CS J=1-0 emission line (48.991 GHz) using the Nobeyama Millimeter Array (NMA) to reveal the detailed structure of the star forming regions near the Galactic center.

Millimeter-wave continuum sources in NGC 7538 region were observed with the NRO 45-m telescope and Nobeyama Millimeter Array. NRO 45-m telescope observations showed that the compact region which includes IRS1, IRS2, and IRS3 has a strong millimeter-wave intensity excess, cf. figures 1, and 2.

We have observed CO(J=3-2) emission of the z=2.286 galaxy IRAS F10214+4724 using the Nobeyama Millimeter Array.

Aperture synthesis CS(J=l-0) observations were made of the expanding clumpy shocked shell that was found around the redshifted CO outflow in NGC 2071 during our previous study (Kitamura et al. 1990). It has been revealed that previously identified clumps in the shell comprise several small subclumps. The decelerating shock and Rayleigh-Taylor instabilities seem to be probable mechanisms by which the subclumps are formed in the shock-compressed shell.

Dense gas in molecular cloud cores is essential in researches of extragalactic star formation (e.g. Solomon, Downes, and Radford). To determine the physical relations between star-forming regions and dense gas, we have observed CS (J=3→2) in starburst galaxies M 82 and NGC253. The J = 3 level of CS is 14.1 K and the critical density for excitation is 4 × 105 cm−3.

The Nobeyama Millimeter Array Survey for protoplanetary disks has been made for 19 protostellar IRAS sources in Taurus; 13 were invisible protostars and 6 were youngest T Tauri stars. We observed the 98 GHz continuum and CS(J=2-1) line emissions simultaneously with spatial resolutions of 2.8”- 8.8” (360 AU-1,200 AU). Unresolved continuum emission was detected from 5 of 6 T Tauri stars and 2 of 13 protostar candidates. The continuum emission arose from compact circumstellar disks. Extended CS emission was detected around 2 T Tauri stars and 11 protostar candidates. There is a remarkable tendency for the detectability for the 98 GHz continuum emission to be small for protostar candidates. This tendency is explained if the mass of protoplanetary disks around protostars is not as large as that around T Tauri stars; the disk mass may increase with the increase of central stellar mass by dynamical accretion in the course of evolution from protostars to T Tauri stars.

We present 6″ (460 pc at a distance of 9.6 Mpc) resolution CO(J=1−0) map of the central region of the grand-design spiral galaxy M51 and very preliminary 4″ (180pc) resolution CO(J=1−0) map of the arm regions, using the Nobeyama Millimeter Array (NMA). The central 3kpc region (1') was mapped with a velocity resolution of 20km/s, and the rest with 10km/s.

We have observed the 12CO (Ishizuki et al 1990) and 13CO emission of the central 65″ region of the galaxy IC342 at the high resolutions of 2.4″ for 12CO and 5.1″×4.2″ for 13CO using the Nobeyama Millimeter Array. The integrated intensities of 12CO and 13CO emission are shown in Fig.1 and 2, respectively.

The problem of determining the optimum number of components in fitting a Gaussian model to aperture synthesis data is considered. As a measure of the badness of the fitted model, we propose the use of Akaike’s Information Criterion (AIC).