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A Glimpse into the Past: The Recent Evolution of Globular Clusters
Anderson, Jay; Strader, Jay; Richer, Harvey B. +1 more
We present the serendipitous discovery of 195 extragalactic globular clusters (GCs) in one of the deepest optical images ever obtained, a 126 orbit Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) imaging study of the nearby Galactic GC NGC 6397. The distant GCs are all found surrounding a bright elliptical galaxy in the field and ar…
Late-Time HST Photometry of SN 1994I: Hints of Positron Annihilation Energy Deposition
Filippenko, Alexei V.; Garnavich, Peter; Fransson, Claes +12 more
We present multicolor Hubble Space Telescope (HST) WFPC2 broadband observations of the Type Ic SN 1994I obtained ∼280 d after maximum light. We measure the brightness of the SN and, relying on the detailed spectroscopic database of SN 1994I, we transform the ground-based photometry obtained at early times to the HST photometric system, deriving li…
Heliospheric sector boundaries: Single or multiple?
Neugebauer, Marcia
Solar wind data were examined for a period when the Ulysses spacecraft moved roughly parallel to the boundary between inward and outward interplanetary fields at a solar distance of 1.4 AU. Multiple crossings of the magnetic sector boundary were observed. Three tests were used to evaluate whether or not the crossings were due to multiple crossings…
Saturnian icy satellites: Disk-integrated observations of the brightness opposition surge at low phase angles
Kulyk, Irina
Photopolarimetric observations of Saturn's satellites Enceladus, Tethys, Dione, and Rhea were obtained with the 2 m RCC telescope at the National Astronomical Observatory, Rozhen, in two different phase-angle regions (from 0.07° to 0.01° and from 5.6° to 5.2°). In this paper we present the first results of disk-integrated satellite photometry incl…
A study of the X-ray pulsars X1845-024 and XTE J1858+034 based on INTEGRAL observations
Doroshenko, V. A.; Doroshenko, R. F.; Postnov, K. A. +2 more
We present an analysis of observations of the relatively unstudied X-ray pulsars X1845-024 and XTE J1858+034 carried out from May 2003 through November 2004 using the JEM-X and IBIS telescopes of the INTEGRAL international gamma-ray observatory at energies of 5-70 keV. The X-ray spectra and light curves of the pulsars are constructed. During the o…
Rosetta in the year of the swing-bys
Montagnon, Elsa; Ferri, Paolo; Accomazzo, Andrea +1 more
The International Rosetta Mission, a cornerstone mission of the European Space Agency Scientific Programme, was launched on 2nd March 2004 on its 10 years journey towards a rendezvous with comet Churyumov-Gerasimenko. Once reached the comet nucleus in summer 2014, Rosetta will orbit it for about 1.5 years down to distances of a few kilometres and …
Meteoroid and space debris impacts in grazing-incidence telescopes
Carpenter, J. D.; Wells, A.; Abbey, A. F. +1 more
Context: Micrometeoroid or space debris impacts have been observed in the focal planes of the XMM-Newton and Swift-XRT (X-ray Telescope) X-ray observatories. These impacts have resulted in damage to, and in one case the failure of, focal-plane Charge-Coupled Device (CCDs) detectors.
Aims: We aim to quantify the future risks of focal-plane impa…
The X-ray emission of the most luminous 3CR radio sources
Salvati, M.; Risaliti, G.; Véron, P. +1 more
Context: Although many radio-loud quasars and galaxies have been observed in X-rays, systematic studies of well defined samples are rare.
Aims: We investigate the X-ray properties of the most luminous radio sources in the 3CR catalogue, in order to assess whether they are similar to the most luminous radio-quiet quasars, for instance in the X-…
Normal Globular Cluster Systems in Massive Low Surface Brightness Galaxies
Jordán, Andrés; Kissler-Patig, Markus; Goudfrooij, Paul +2 more
We present the results of a study of the globular cluster systems of six massive spiral galaxies, originally cataloged as low surface brightness (LSB) but here shown to span a wide range of surface brightness values, including two intermediate to LSB galaxies. We used the Advanced Camera for Surveys on-board Hubble Space Telescope to obtain photom…
Modeling the arrival at Earth of the interplanetary shock following the 12 May 1997 solar event using HAFv2 and 3-D MHD HHMS models
Dryer, M.; Fry, C. D.; Sun, W. +3 more
The 12 May 1997 solar event is used to demonstrate the improvements that have been made in recent years in the accuracy of predicting, in the operational environment, the time of arrival at Earth of solar-caused interplanetary shocks. This event provides a simple test case because it was both well isolated in time from other events and well docume…