We present a 10-year X-ray light curve and the spectra of a peculiar X-ray transient in the spiral galaxy M81. The source was below the detection limit of ROSAT PSPC before 1993, but it brightened substantially in 1993, with luminosities exceeding the Eddington limit of a 1.5-M⊙ compact accretor. It then faded and was not firmly detected in the ROSAT HRI and PSPC observations after 1994. The Ch...

We describe a newly refined procedure for making optical identifications of radio sources in Abell cluster fields observed with the Molonglo Observatory Synthesis Telescope (MOST). The method is based on past experience but uses a range of new tools to improve the reliability and production rate of identification lists. The COSMOS/UKST Southern Sky Object Catalogue was used to make preliminary ...

We report on a preliminary analysis of a 5600 sec per point survey of 32 square degrees in Centaurus, carried out with the Parkes 13-beam system. The signal-to-noise ratio is found to improve as √ tobs for the whole integration. We have detected 102 HI sources between +250 and +12,700 km s−1 either by eye or by using the new galaxy-finding algorithm PICASSO. Over half of these are new HI detect...

This highly original paper relates the $e\phantom{\rule{0}{0ex}}x\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}t$ $r\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}z\phantom{\rule{0}{0ex}}a\phantom{\rule{0...

A population of gliding $C\phantom{\rule{0}{0ex}}h\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}y\phantom{\rule{0}{0ex}}d\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}s$ $r\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}n\phanto...

Euclidean rotations in R2 are bijective and isometric maps, but they generally lose these properties when digitized in discrete spaces. In particular, the topological and geometric defects of digitized rigid motions on the square grid have been studied. This problem is related to the incompatibility between the square grid and rotations; in general, one has to accept either relatively high loss...

background: in myocardial perfusion spect imaging, images are degraded by photon attenuation, the distance-dependent collimator, detector response and photons scatter. filters greatly affect quality of nuclear medicine images materials and methods: a phantom simulating heart left ventricle was built. about 1mci of 99mtc was injected into the phantom. images were taken from this phantom. some fi...