Search Publications
Network Synthesis Localization of Two Soft Gamma Repeaters
Cline, T.; Kouveliotou, C.; Sommer, M. +5 more
We introduce the method of 'network synthesis,' which allows the detection of very weak gamma-ray transient signals in the data of the Ulysses gamma-ray burst (GRB) experiment from repeating sources. It consists of defining a grid of alpha, delta values, and for each BATSE detection of a burst from a soft gamma repeater, predicting the arrival tim…
The Far-Ultraviolet Dust Albedo in the Upper Scorpius Subgroup of the Scorpius OB2 Association
Gordon, Karl D.; Witt, Adolf N.; Carruthers, George R. +2 more
During NRL's Far Ultraviolet Cameras experiment on STS-39, four images of the giant reflection nebula encompassing the Upper Scorpius subgroup of the Sco OB2 association were obtained in two ultraviolet bandpasses with lambdaeff = 1362 A and 1769 A. From these images and IUE and TD-1 stellar spectra, the ratio of nebular to stellar flux…
Observing Stellar Coronae with the Goddard High Resolution Spectrograph. I. The dMe Star AU Microscopii
Carpenter, K. G.; Linsky, J. L.; Shore, S. N. +11 more
We report on an observation of AU Mic taken with the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope. The data consist of a rapid sequence of spectra covering the wavelength range 1345-1375 A with a spectral resolution of 10,000. The observations were originally intended to search for spectral variations during flares…
WFPC2 Observations of the Double Cluster NGC 1850 in the Large Magellanic Cloud
Panagia, N.; Ewald, S. P.; Romaniello, M. +2 more
HST-WFPC2 optical and ultraviolet imaging observations of the young double cluster NGC 1850 in the LMC are presented. The main cluster, NGC 1850A, is a globular-like cluster and has an age of 50+/-10 Myr, while the subcluster, NGC 1850B, which is more loosely distributed, is very young at 4.3 +/- 0.9 Myr. Its young age is confirmed by the detectio…
Hubble Space Telescope Goddard High-Resolution Spectrograph H 2 Rotational Spectra of Jupiter's Aurora
Vidal-Madjar, Alfred; Clarke, John T.; Ben Jaffel, Lotfi +6 more
We have observed the emission spectrum from Jupiter's north auroral atmosphere with 0.57 A spectral resolution over 1204-1241 A. Bright emissions have been detected from 50 deg to 60 deg latitude at locations consistent with 6 to 30 R J auroral ovals, with much fainter emissions away form the auroral ovals. The emission spectrum is well…
Multiwavelength Observations of Hercules X-1/HZ Herculis
Mihara, T.; Kahabka, P.; Charles, P. A. +16 more
We present first results from a multiwavelength campaign to observe the binary pulsar system Her X-1/ HZ Her. The campaign spanned 4 days during 1993 August: observations were taken with five satellites (IUE, EUVE, ROSAT, ASCA, and CGRO/BATSE) and several ground-based facilities. A substantial, unexpected drop in flux at X-ray energies, with no ch…
The Theta -z Relation for HST Bulges and Disks out to Z 0.8
Casertano, Stefano; Glazebrook, Karl; Green, Richard F. +9 more
We present HST scale lengths and ground-based redshifts for 63 faint field galaxies down to I <~ 21.5 mag from the Medium-Deep Survey. These have measured redshifts z <~ 0.8 and half-light radii 0.1" < r_e_, r_s_ < 5". We present the {THETA}-z relation for r^1/4^-bulges and exponential disks separately for world models with q_0_ = 0.0-…
Deep HST Imaging of Distant Weak Radio and Field Galaxies
Dunlop, J. S.; Keel, W. C.; Windhorst, R. A. +4 more
We present deep Hubble Space Telescope (HST) Wide-Field Camera V- and I-band images of three distant weak radio galaxies with z = 0.311-2.390 and seven field galaxies with z = 0.131-0.58. The images were deconvolved with both the Lucy and multiresolution CLEAN methods, which yield a restoring FWHM of <= 0.2", (nearly) preserve photons and signa…
HST Imaging of Quasi-stellar Objects with WFPC2
Holtzman, Jon; Sparks, W. B.; Hutchings, J. B. +3 more
Early images were taken with the optically corrected WFPC2 camera of the Hubble Space Telescope of the low-redshift QSOs 1229+204 and 2141+175, which are radio-quiet and radio-loud, respectively. We discuss image restoration on the data. The objects were chosen on the basis of structure seen with 0.5" resolution with the CFHT high-resolution camer…
X-Ray Emission from a Simulated Cluster of Galaxies
Katz, Neal; Tsai, John C.; Bertschinger, Edmund
Using the 1993 cluster simulation of Katz & White, we analyze the intracluster medium and investigate the accuracy of the standard hydrostatic method for determining cluster masses. We show that the simulated cluster gas is in hydrostatic equilibrium with a subsonic flow toward the center. Inside a radius of ∼100 kpc, this flow is in a steady …