When Dunsink Observatory, Dublin, became operational, in 1785, it was expecting to install a large transit circle by Ramsden. Due to problems with its construction, and maybe also with the commissioner (Henry Ussher, first Andrews Professor of Astronomy at Trinity College Dublin and founder of the observatory), the Ramsden workshop delivered the circle only in 1808, after the death of Ramsden in 1800. The history of the Dunsink Ramsden Circle features in a recent contribution to this journal by I. Chinnici, who focuses on G. Piazzi’s procurement of the Palermo Ramsden Circle. She also recounts the eventual loss of the Dunsink Circle, which was stolen in 1981 from an outbuilding of the Observatory where it had been stored following a fire in its Meridian Room in 1977. It may be of interest to know that there is, in fact, a remaining piece of the Ramsden Circle at Dunsink: the objective of the telescope that formed part of it (Figure 1). When I became Director of Dunsink Observatory in 1994, I kindly received a set of personal notes on the observatory drawn up by my predecessor, Patrick Wayman, that includes a few further details on the Ramsden Circle and notably alerted me that the objective lens was still in existence. Dunsink was reactivated in 1947 after a ten year’s closure and the first Director after this interval, Hermann Brück, championed a renewal of observing equipment at Dunsink. According to Wayman, Brück and his JHA, xli (2010)

HD 34921 (= BD+37◦1160) has been identified as the counterpart of the X-ray source 4U 0515+38 (= 1H 0521+373). Presently, the star is classified optically as B0III-IVpe. The likely association with the IRAS source 05192+3737 suggests a dust envelope. This is quite uncommon between the High Mass X-Ray Binaries (HMXBs), but for the CI Cam/XTE J0421+560 system. Strong analogies in the infrared spectra of HD 34921 and CI Cam, referring to dust shell and very complex circumstellar environment, led Clark et al. (1999) to classify both stars as B[e] stars, the only known HMXRB optical counterpart of this type. Here we argue that HD34921 is not properly a B[e] star. 1. The X-ray Transient HD34921 (= BD+37◦1160) was identified as counterpart of the X-ray source 4U 0515+38 by Polcaro et al. (1990). After the original Uhuru observations, this Xray transient was detected again by HEAO1 as 1H 0521+373, at a much lower flux level. Subsequent balloon-borne hard X-ray telescopes also detected this source, in 1980 and 1981 (Ubertini et al. 1982; Polcaro et al. 1984). An EXOSAT pointed observation in 1985 resulted in a detection with the LE instrument, but upper limits with the two ME detectors (Polcaro et al. 1990). Since then 4U 0515+38 has not been seen anymore at high energies. Data for the 2-7 keV band are shown in Fig. 1. Also instructive is a plot with the hard X-ray data obtained by Uhuru and the balloon-borne hard X-ray telescopes (Fig. 2).

As the nearest galaxies around us, the Local Group systems offer especially good opportunities for observations of their nuclear X-ray radiation. Certain or possible nuclear X-ray sources in the Local Group suggest a minimum luminosity for activity to become manifest.

We have collected from the literature X-ray fluxes of Young Supernovae, measured with various instruments. After converting the data to one energy range, we have compared the X-ray light curves of these objects. The X-ray luminosities of early Supernovae show coherent trends with Supernova type and provide significant, though short-lived contributions to the X-ray luminosity of Starbursts.

We present the first high-resolution observations of the optical afterglow of a gamma-ray burst. The spectra show that the matter of the host galaxy in the circumburst region is complex, with many components contributing to each system. Also the presence of low- and high-ionisation lines allows rather strong constraints on the gas ionisation parameters of the various components to be derived. These can be interpreted as density fluctuations on top of a regular R-2 wind density profile.

We present the first high-resolution (R = 20; 000 45; 000, corresponding to 14 km s(-1) at 4200 angstrom to 6.6 km s(-1) at 9000 angstrom) observations of the optical afterglow of gamma-ray bursts. GRB 020813 and GRB 021004 were observed by UVES at the Very Large Telescope 22.19 and 13.52 hr after the trigger, respectively. These spectra show that the interstellar matter of the GRB host galaxies is complex, with many components contributing to each main absorption system, and spans a total velocity range of up to about 3000 km s(-1). Several narrow components are resolved down to a width of a few tens of km s(-1). In the case of GRB 021004 we detected both low- and high-ionization lines. Combined with photoionization results obtained with CLOUDY, the ionization parameters of the various systems are consistent with a remarkably narrow range with no clear trend with system velocity. This can be interpreted as due to density fluctuations on top of a regular R-2 wind density profile.

Recent observations have suggested that the true energy release of GRBs is potentially far less than previously thought. This is due to beaming, a signature of which is a broadband break in the power-law decay of the afterglow emission. Taking these results we have constructed a basic distance estimator, which may be useful as a diagnostic tool for the large amount of GRBs without a spectroscopically measured redshift.

HD34921 has been identified as the counterpart of the X-ray source 4U0515+38 (=1H0521+373). The InfraRed properties are reminiscent of the B[e] system CI Cam. Optical short-term variability suggests a compact companion. We discuss how this system fits in the overall framework of Be stars and X-ray binaries.

REM is a fast slewing automatic telescope dedicated to the prompt observation of GRB afterglows. The telescope automatically reacts to GCN alerts, beginning follow-up observations in both infra-red and optical wavelengths. Recent observations of GRBs have shown the capabilities of REM to begin follow up observation in the order of 10s of seconds after the burst.

Interpretative analyses of the X-ray emission from the giant starformation region R 136 have concluded that several colliding-wind binaries are likely to contribute to its X-ray output. Using our dedicated high-energy stellar population synthesis programme, we try to reproduce the suggested number of colliding-wind binaries. It appears that only assuming a very high binary fraction for the cluster's stellar population we can reproduce the observed X-ray luminosity distribution, if also the two most luminous sources are in fact multiple sources.

The original idea for this IAU Symposium arose from realizing that present-day X-ray satellites, XMM-Newton and Chandra, are now allowing us to conduct studies of individual X-ray sources in other galaxies, much like this was until recently mostly confined to sources in our own Galaxy and in the Magellanic Clouds. In addition, -ray astronomy is catching up as it were, now being able to study well-defined sources in our own Galaxy with the INTEGRAL satellite, and also the highest-energy sources accessible, at TeV, with the newly constructed Cherenkov receiver array(s).

Spectra are modeled for observations with the ROSAT PSPC, using 3 models namely Thermal Bremsstrahlung, Raymond-Smith and an Absorbed Power law. For each model a range of parameters are modeled. Hardness Ratios are calculated for each simulation and a grid of HR1 versus HR2 is produced for each of the three models. Hardness Ratios, from observations which do not have enough spectral counts to fit spectra directly, may be compared with the grid to set limits on observational parameters e.g temperature.

In several instances GRB afterglows have been found to be associated with Supernova features. Examination of available observational data on afterglow redshifts suggests that most or all GRBs could be linked to a SN. The relevance of this for distance determinations is briefly considered.