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The Optical Contents of the IPN1 Localization of GRB 790325B: The Discovery of a Probable QSO Association

Vrba, Frederick J.; Luginbuhl, Christian B.; Hartmann, Dieter H. +1 more

We report the results of the deepest imaging survey yet carried out of the IPN1 localization of gamma-ray burst (GRB) 790325b. While this is one of the smallest of the IPN1 GRB localizations, it has been previously surveyed only to shallow limits because of the nearby bright (V=4.97) star 104 Herculis. We have used a camera with a 9 mag neutral de…

On the expansion of stellar association Per OB2

Mirzoyan, L. V.; Hambaryan, V. V.; Akopian, A. A. +2 more

The analysis of the proper motions of bright members of the Per OB2 association on the basis of Hipparcos high-accuracy astromethc observations is presented. The existence of two different subgroups of OB-stars in the Per OB2 association that are in the state of expansion is considered. The expansion ages are calculated as 1.3 and 1.9×10⁶

Propagation of the Onset of Modulation in Cycle 23 from 1 to 72 AU

Krimigis, S. M.; Simpson, J. A.; Zhang, M. +3 more

In late 1997, the modulation of galactic cosmic rays at 1 AU began to increase in response to increasing solar activity. We report observations of the onset of modulation from spacecraft ranging from IMP-8 and U l y s s e s near the ecliptic at 1 AU and 5 AU respectively out to Voyager 1 and 2 , in the northern and southern solar hemispheres at ra…

Comparing Quiet Sun and Coronal Hole Regions with CDS/SOHO

Young, P. R.; Esser, R.

Spectra from the Coronal Diagnostic Spectrometer on board SOHO are used to compare density and temperature in coronal hole and quiet Sun regions.

Scattering mean free path of energetic protons in the Heliosphere

Balogh, A.; Erdos, Geza; Jota, J.

The effect of magnetic field fluctuations on charged particle propagation is investigated. Quasi-linear theory is used to deduce the diffusion coefficient of energetic particles from magnetic field data measured by Ulysses at high heliographic latitude. The λQLT scattering mean free path of 1 MeV protons is determined along one complete off-eclipt…

Observation of Transition Region Fine Structures with Soho/Sumer

Mason, H. E.; Landini, M.; Landi, E.

We present a preliminary analysis of two quiet Sun transition region areas observed with the SOHO/SUMER spectrometer, using lines from oxygen, nitrogen and silicon. The average quiet Sun physical parameters are studied as a function of line intensity. Systematic variations of line position and width with increasing intensity are found. A large num…

Comparative morphology of EIT/SOHO images and He II excitation

Venkatakrishnan, P.

Morphological differences between coronal images on the one hand, and a He i image on the other, are used to demonstrate the independence of He ii excitation from coronal radiation. The distribution of magnetic flux is found to be more important for He ii excitation. Collisional excitation by non-thermal electrons produced in nano-flare events is …

Hot massive stars in Local Group galaxies.

Bianchi, L.; Scuderi, S.

Absolute declinations with the photoelectric astrolabe at Calern Observatory (OCA)

Leister, N. V.; Martin, V. A. F.; Vigouroux, G. +2 more

A regular observational programme with a photoelectric astrolabe have been performed at ``Observatoire du Calern" (Observatoire de la Côte d'Azur, OCA, phi = +43() o44‧55.011″; lambda = -0() h27() m42.44() s, Calern, Caussols, France) for the last twenty years. It has been almost fully automatized between 1984 and 1987. Since 1988 the photoelectri…

NICMOS observations of luminous & ultraluminous infrared galaxies

Evans, Aaron S.

HST NICMOS observations of a sample of 24 luminous (LIGs: L_IR[8-1000 µm] = 10^11.0-11.99 L_⊙) and ultraluminous (ULIGs:L_IR ≳ 10^12.0 L_⊙) infrared galaxies are presented.The observations provide, for the first time, high resolution HST imagingof the imbedded 1.1 - 2.2 µm nuc…