Now showing items 1-20 of 130

  • Observatoriet i 80-årene 

    Trulsen, Jan (Journal article; Tidsskriftartikkel, 1980)
    På terskelen til en ny dekade er det naturlig å stille spørsmålet hva Observatoriets fremtidige rolle skal bli. Vil det fortsatt være behov for forskningsinnsats på Observatoriets tradisjonelle fagfelter, eller skal innsatsen ...
  • Nordlys i verdensrommet 

    Havnes, Ove (Journal article; Tidsskriftartikkel, 1980)
    Vi vil ikke her gå inn i nordlyset som vi kjenner det fra jorden, men kort omtale andre steder i verdensrommet hvor vi har observert nordlyslignende fenomen eller hvor vi kan vente å finne beslektede fenomen.
  • Nordlysobservatoriet i dag 

    Solheim, Jan-Erik (Journal article; Tidsskriftartikkel, 1980)
    Da Det Norske Institutt for Kosmisk Fysikk ble del av Universitetet i Tromsø, opphørte Nordlysobservatoriet å eksistere som en formell enhet. Det som i dag omfattes av Nordlysobservatoriet, er dels en fortsettelse av den ...
  • Enhancement of stratospheric aerosols after solar proton event. 

    Shumilov, O.I.; Henriksen, K.; Kasatkina, E.A.; Vashenyuk, E.V. (Journal article, 1996)
    The lidar measurements at Verhnetulomski observatory (68.6¡N, 31.8¡E) at Kola peninsula detected a considerable increase of stratospheric aerosol concentration after the solar proton event of GLE (ground level event) ...
  • Understanding the Cool DA White Dwarf Pulsator, G29–38 

    Kleinman, S. J.; Solheim, Jan Erik; Nather, R. E.; Bruvold, A.; Winget, D. E.; Clemens, J. C.; Bradley, A.; Kanaan, A.; Claver, C. F.; Watson, T. K.; Yanagida, K.; Nitta, A.; Dixson, J. S.; Grauer, A. D.; Hine, B. P.; Fontaine, G.; Liebert, James; Sullivan, D. J.; Wickramasinghe, D. T.; Achilleos, N.; Mara, T. M. K.; Seetha, S.; Ashoka, B. N.; Leibowitz, E. M.; Moskalik, P.; Krzesi´nski, J.; O’Donoghue, D.; Kurtz, D. W.; Warner, B.; Martinez, Peter; Dolez, N.; Chevreton, M.; Barstow, M. A.; Kepler, S. O.; Giovannini, O.; Hansen, C. J.; Augusteijn, T. (Journal article; Tidsskriftartikkel; Peer reviewed, 1997-10-10)
    The white dwarfs are promising laboratories for the study of cosmochronology and stellar evolution. Through observations of the pulsating white dwarfs, we can measure their internal structures and compositions, critical ...
  • Electron velocity distribution function in a plasma with temperature gradient and in the presence of suprathermal electrons: application to incoherent-scatter plasma lines. 

    Lilensten, J.; Guio, Patrick; Kofman, W.; Bjørnå, Noralv (Journal article, 1998)
    The plasma dispersion function and the reduced velocity distribution function are calculated numerically for any arbitrary velocity distribution function with cylindrical symmetry along the magnetic field. The electron ...
  • Superposed epoch analysis applied to large-amplitude travelling convection vortices. 

    Lühr, H.; Hansen, T.L.; Rother, M.; Iyemori, T.; Lepping, R.P. (Journal article, 1998)
    For the six months from 1 October 1993 to 1 April 1994 the recordings of the IMAGE magnetometer network have been surveyed in a search for large- amplitude travelling convection vortices (TCVs). The restriction to large ...
  • Spectral characteristics of spring arctic mesosphere dynamics. 

    Manson, A.H.; Hall, Chris; Meek, C.E. (Journal article, 1998)
    The spring of 1997 has represented a stable period of operation for the joint University of Tromsù / University of Saskatchewan MF radar, being between refurbishment and upgrades. We examine the horizontal winds from ...
  • Observations of thermospheric neutral winds within the polar cusp and the auroral oval using a Doppler imaging system (DIS). 

    Henriksen, K.; Rees, D.; Smith, R.W.; Signernes, F.; Brandstrom, U.; Harris, M.; Maskall, G. (Journal article, 1998)
    Two Doppler imaging systems (DIS) or wide-field imaging Fabry-Perot interferometers (FPI), have recently been commissioned, one at the Auroral Station, Adventdalen, Longyearbyen, Svalbard, and the second at the IRF, Kiruna, ...
  • Three photometric methods tested on ground-based data of Q 2237+0305 

    Østensen, R.; Burud, I.; Stabell, R.; Magain, P.; Courbin, F.; Refsda, S.; Remy, M.; Teuber, J. (Journal article; Tidsskriftartikkel; Peer reviewed, 1998-09-09)
    The Einstein Cross, Q 2237+0305, has been photometrically observed in four bands on two successive nights at NOT (La Palma, Spain) in October 1995. Three independent algorithms have been used to analyse the data: an ...
  • Effect of suprathermal electrons on the intensity and Doppler frequency of electron plasma lines. 

    Guio, Patrick; Lilensten, J. (Journal article, 1999)
    In an incoherent scattering radar experiment, the spectral measurement of the so-called up- and downshifted electron plasma lines provides information about their intensity and their Doppler frequency. These two spectral ...
  • Irregular structures of the F layer at high latitudes during ionospheric heating. 

    Tereshchenko, E.D.; Rietveld, Michael T.; Kozlova, M.O.; Brekke, Asgeir; Evstafiev, O.V.; Khudukon, B.Z.; Nygren, T. (Journal article; Peer reviewed, 2000)
    Results on heating the ionospheric F region above Tromsø, Norway are presented. The ionosphere was monitored by satellite tomography and amplitude scintillation methods as well as the EISCAT incoherent scatter radar. No ...
  • Comparison of the orientation of small-scale electron density irregularities and F region plasma flow direction. 

    Rietveld, Michael T.; Tereshchenko, E.D.; Brekke, Asgeir; Khudukon, B.Z.; Kozlova, M.O.; Evstafiev, O.V.; Nygren, T. (Journal article; Peer reviewed, 2000)
    Results are shown from an experimental campaign where satellite scintillation was observed at three sites at high latitudes and, simultaneously, the F region plasma flow was measured by the nearby EISCAT incoherent scatter ...
  • Plasma density over Svalbard during the ISBJØRN campaign. 

    Van Eyken, A.P.; Hall, Chris; Svenes, K.R. (Journal article; Peer reviewed, 2000)
    In 1997, reliable operation of the EISCAT Svalbard Radar (ESR) was achieved and a rocket launching facility at Ny Ålesund on Svalbard (79°N, 12°E) (SVALRAK) was established. On 20 November, 1977, the first instrumented ...
  • MIDAS-W: a workstation-based incoherent scatter radar data aquisition system. 

    Holt, J.M.; Grydeland, Tom; Erickson, P.J.; Gorczyca, A.M. (Journal article, 2000)
    The Millstone Hill Incoherent Scatter Data Acquisition System (MIDAS) is based on an abstract model of an incoherent scatter radar. This model is implemented in a hierarchical software system, which serves to isolate ...
  • Geomagnetic control of polar mesosphere summer echoes. 

    Hansen, T.L.; Bremer, J.; Hoffmann, P. (Journal article, 2000)
    Using observations with the ALOMAR SOUSY radar near Andenes (69.3°N, 16.0°E) from 1994 until 1997 polar mesosphere summer echoes (PMSE) have been investigated in dependence on geomagnetic K indices derived at the Auroral ...
  • Multiwavelength observations revealing the outbursts of the two soft X-ray transients XTE J1859+226 and XTE J1118+480 

    Solheim, Jan Erik; Chaty, S.; Haswell, C.A.; Østensen, R.; Hynes, R.I.; Shrader, C.R.; Cui, W.; Mauche, C.W.; Norton, A.J.; Geballe, T.R.; Ioannou, Z.; King, A.R. (Conference object; Konferansebidrag, 2001-02-06)
    We report here on multiwavelength observations of the two new soft X-ray transients (SXTs) XTE J1859+226 and XTE J1118+480, which we observed with HST/RXTE/UKIRT. For XTE J1118+480 we also used EUVE since it is located ...
  • The optical afterglow and host galaxy of GRB 000926 

    Fynbo, J.U.; Østensen, R.; Gorosabe, J.; Solheim, Jan Erik; Dall, T.H.; Hjorth, J.; Pedersen, H.; Andersen, M.I.; Møller, P.; Holland, S.; Smail, I.; Kobayashi, N.; Rol, E.; Vreeswijk, P.; Vrba, F.; Burud, I.; Jensen, B.L.; Henden, A.; Thomsen, B.; Canzian, B.; Castro Cer´on, J.M.; Castro-Tirado, A.J.; Cline, T.; Goto, M.; Greiner, J.; Hanski, M.T.; Hurley, K.; Pursimo, T.; Lund, N.; Tanvir, N.; Terada, H. (Journal article; Tidsskriftartikkel, 2001-04-11)
    We present the discovery of the Optical Transient (OT) of the long–duration gamma-ray burst GRB 000926. The optical transient was detected independently with the Nordic Optical Telescope and at Calar Alto 22.2 hours after ...
  • HS 0705+6700: a new eclipsing sdB binary 

    Østensen, R.; Solheim, Jan Erik; Johannessen, F. (Journal article; Tidsskriftartikkel, 2001-10-09)
    We report the discovery of an eclipsing binary – HS 0705+6700 – being an sdB star with a faint companion. From its light curve the orbital period of 8263.87 s, the mass ratio of the system q = 0.28, the inclination ...
  • Seasonal variations of the semi-diurnal and diurnal tides in the MLT: multi-year MF radar observations from 2–70 N, modelled tides (GSWM, CMAM) 

    Hall, Chris; Manson, A.H.; Meek, C.; Hagan, M.; Koshyk, J.; Franke, S.; Fritts, D.; Hocking, W.; Igarashi, K.; MacDougall, J.; Riggin, D.; Vincent, R. (Journal article; Peer reviewed, 2002)
    In an earlier paper (Manson et al., 1999a) tidal data (1990–1997) from six Medium Frequency Radars (MFR) were compared with the Global Scale Wave Model (GSWM, original 1995 version). The radars are located between the ...