Search Publications
SDSS J124602.54 + 011318.8: A Highly Luminous Optical Transient at z = 0.385
Schneider, Donald P.; York, Donald G.; Hurley, Kevin +30 more
We report the discovery of a highly luminous optical transient (OT), SDSS J124602.54 + 011318.8, associated with a galaxy at a redshift of 0.385. In this paper, we consider the possibility that the OT may be a gamma-ray burst (GRB) afterglow. Three sets of images and two sets of spectra were obtained as part of the normal operations of the Sloan D…
The Redshift of a Lensing Galaxy in PMN J0134-0931
Bowen, David V.; Hall, Patrick B.; Brinkmann, J. +5 more
The Sloan Digital Sky Survey (SDSS) automatically targeted as a quasar candidate the recently discovered, gravitationally lensed, extremely reddened z=2.2 quasar PMN 0134-0931. The SDSS spectrum exhibits Ca II absorption at z=0.76451, which we identify as the redshift of a lensing galaxy. Hubble Space Telescope imaging shows that components C, D, …
XMM-Newton Observations of a Possible Light Echo in the Seyfert 1 Nucleus of NGC 4051
Maraschi, L.; Page, M. J.; Uttley, P. +6 more
We discuss a 1.5 day long observation of the bright variable Seyfert 1 galaxy NGC 4051 that was obtained with the X-ray and ultraviolet telescopes on XMM-Newton and extended in the X-ray band using the Rossi X-Ray Timing Explorer. The ultraviolet (2900 Å) and X-ray (2-10 keV) light curves varied with peak-to-peak amplitudes of 5% and a factor of ~…
The Discovery of a 2.78 Hour Periodic Modulation of the X-Ray Flux from Globular Cluster Source Bo 158 in M31
Mason, Keith O.; Watson, Michael G.; Cordova, France A. +4 more
We report the discovery of periodic intensity dips in the X-ray source XMMU J004314.1+410724, in the globular cluster Bo 158 in M31. The X-ray flux was modulated by ~83% at a period of 2.78 hr (10,017 s) in an XMM-Newton observation taken 2002 January 6-7. The X-ray intensity dips show no energy dependence. We detected weaker dips with the same pe…
Sudden Disappearance of a Small Sunspot Associated with the 2002 February 20 M2.4 Flare
Liu, Chang; Qiu, Jiong; Wang, Haimin +3 more
In this Letter, we present the evidence of rapid disappearance of a small sunspot associated with a M2.4 flare, which occurred in NOAA Active Region 9830, at 2106 UT, on 2002 February 20. The sunspot, in the size of about 45 arcsec2, completely disappeared in about 60 minutes, coinciding with the onset of the flare. The magnetic flux of…
Cool White Dwarfs in Cataclysmic Variables: Hubble Space Telescope Results on EG Cancri and HV Virginis
Szkody, Paula; Howell, Steve B.; Sion, Edward M. +1 more
Our Hubble Space Telescope (HST) ultraviolet spectra of the low mass transfer rate cataclysmic variables EG Cnc and HV Vir at 4 yr and 8 yr past their last superoutburst have shown that the white dwarfs in these systems are among the coolest yet observed in disk-accreting close binaries. The UV-optical fluxes of EG Cnc are consistent with a 11,700…
Is There a 1998bw-like Supernova in the Afterglow of Gamma-Ray Burst 011121?
Dar, Arnon; Dado, Shlomo; De Rújula, A.
We use the very simple and successful cannonball model of gamma-ray bursts (GRBs) and their afterglows (AGs) to analyze the observations of the strongly extinct optical AG of the relatively nearby GRB 011121; these observations were made with ground-based telescopes at early times and with the Hubble Space Telescope at later times. We show that GR…
A Proper-Motion Survey for White Dwarfs with the Wide Field Planetary Camera 2
Alcock, C.; Axelrod, T. S.; Cook, K. H. +2 more
We have performed a search for halo white dwarfs as high proper motion objects in a second-epoch Wide Field Planetary Camera 2 image of the Groth-Westphal strip. The survey covers 74.8 arcmin2 and is complete to V~26.5. We identify 24 high proper motion objects with µ>0.014" yr-1. Five of these high proper motion obj…
Observations of Core Fallback during Coronal Mass Ejections
Sheeley, N. R., Jr.; Wang, Y. -M.
White-light observations made with the Large Angle and Spectrometric Coronagraph (LASCO) during the present solar maximum have revealed a multitude of faint, inward-moving features at heliocentric distances of r~2-6 Rsolar. Most of these structures appear to originate above r~3 Rsolar and may be signatures of the closing-down…
Solar Subsurface Flow Inferred Directly from Frequency-Wavenumber Correlations in the Seismic Velocity Field
Woodard, M. F.
We describe a general strategy for inverting helioseismic data for laterally inhomogeneous (aspherical) structure, in which the physical state of the solar interior is compared directly with inhomogeneity-induced correlations in the observable seismic wave field. The method was used to invert for subsurface supergranular-scale flow using Solar and…