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Hubble Space Telescope and Ground-based Optical and Ultraviolet Observations of GRB 010222
Price, P. A.; Harrison, F. A.; Galama, T. J. +12 more
We report on Hubble Space Telescope (HST) Wide Field Planetary Camera 2 optical and Space Telescope Imaging Spectrograph (STIS) near-ultraviolet MAMA observations and ground-based optical observations of GRB 010222, spanning 15 hr to 71 days. The observations are well described by a relativistic blast wave model with a hard electron energy distrib…
Contrasting the Ultraviolet and X-Ray O VI Column Density Inferred for the Outflow in NGC 5548
Kaastra, Jelle; Korista, Kirk T.; Arav, Nahum +4 more
We compare X-ray and UV spectroscopic observations of NGC 5548. Both data sets show O VI absorption troughs associated with the active galactic nuclei outflow from this galaxy. We find that the robust lower limit on the column density of the O VI X-ray trough is 7 times larger than the column density found in a study of the O VI UV troughs. This d…
Energetic particle propagation in the inner heliosphere as deduced from low-frequency (<100 kHz) observations of type III radio bursts
Cane, H. V.; Erickson, W. C.
Solar energetic particle (SEP) events are well-associated with solar flares. It is observed that the delay between the time of the flare and the first-arriving particles at a spacecraft increases with increasing difference between the flare longitude and the foot point of the field line on which the spacecraft is located. This difference we call t…
Stellar Crowding and the Science Case for Extremely Large Telescopes
Olsen, Knut A. G.; Blum, Robert D.; Rigaut, François
We present a study of the effect of crowding on stellar photometry. We develop an analytical model through which we are able to predict the error in magnitude and color for a given star for any combination of telescope resolution, stellar luminosity function, background surface brightness, and distance. We test our predictions with Monte Carlo sim…
Abundances of Planetary Nebulae BD+30 3639 and NGC 6543
Pottasch, S. R.; Feibelman, W. A.; Bernard-Salas, J. +1 more
Infrared spectra taken with the Short Wavelength Spectrometer on board ISO and UV observations with IUE of planetary nebulae
Solar active regions: The footpoints of 1 MK loops
Del Zanna, G.
On-disc SOHO and TRACE observations of the footpoints of 1 MK quiescent loops in a solar active region are presented. These types of loops are long-lived and high-lying features that are best seen in the TRACE 173 Å passband, sensitive to 1 MK temperatures. SOHO/CDS data are used to show the clear association between the high-lying 1 MK coronal em…
XMM-Newton Observations of Broad Iron Kα Emission from Seyfert 1.9 Galaxy MCG -5-23-16
Schurch, N. J.; Dewangan, G. C.; Griffiths, R. E.
XMM-Newton observations of the bright Seyfert 1.9 galaxy MCG -5-23-16 have revealed a broad Fe Kα emission line that is nearly symmetric in contrast to the broad and redshifted asymmetric Fe Kα line sometimes observed from Seyfert 1 galaxies. The Fe Kα line has two distinct components-a narrow unresolved component with an equivalent width of ~40 e…
IGR J16318-4848: An X-ray Source in a Dense Envelope?
Gilfanov, M. R.; Sunyaev, R. A.; Sazonov, S. Yu. +1 more
We analyze in detail the ASCA observations of the hard X-ray source IGR J16318-4848, which was recently discovered by the INTEGRAL observatory (Courvoisier et al. 2003). The source has an anomalously hard spectrum in the energy range 0.5-10 keV and is virtually undetectable below 4 keV because of strong photoabsorption (n_H L > 4 x 1023
Simultaneous observations of solar transition region blinkers and explosive events by SUMER, CDS and BBSO. Are blinkers, explosive events and spicules the same phenomenon?
Doyle, J. G.; Madjarska, M. S.
The SoHO discovery of the new ``blinker'' phenomena focused our study on the search of its relation to already known phenomena such as explosive events and spicules. The study was performed using a specially planned joint observing program involving the Coronal Diagnostic Spectrometer (CDS), Solar Ultraviolet Measurements of Emitted Radiation spec…
Coronal mass ejections: Initiation and detection
Gopalswamy, N.
Coronal mass ejections (CMEs) are large-scale magnetic structures expelled from the Sun due to MHD processes involving interaction between plasma and magnetic field in closed field regions. I provide a summary of the observational signatures and current models on CME initiation. I also discuss the multiwavelength signatures of CMEs, which have hel…