Now showing items 1-20 of 816

    • Abrupt increase in Greenland snow accumulation at the end of the Younger Dryas event 

      Alley, R. B.; Meeset, D. A.; Shuman, Christopher; Gowt, A. J.; Taylor, K. C.; Grootes, P. M.; White, J. W. C.; Ram, M.; Waddington, E. D.; Mayewski, P. A.; Zielinski, G. A. (Nature, 1993-04-08)
      THE warming at the end of the last glaciation was characterized by a series of abrupt returns to glacial climate, the best-known of which is the Younger Dryas event1. Despite much study of the causes of this event and the ...
    • Composite Temperature Record from the Greenland Summit, 1987–1994: Synthesis of Multiple Automatic Weather Station Records and SSM/I Brightness Temperatures 

      Shuman, Christopher; Bindschadler, R. A.; Fahnestock, M. A.; Alley, R.B.; Stearns, C. R. (AMS, 1996-06-01)
      Air temperature (Tᴀ) records from automatic weather stations (AWS) in central Greenland and associated Special Sensor Microwave/Imager (SSM/I) brightness temperature (Tʙ) data (37 GHz, vertical polarization) have been used ...
    • Postselection-free energy-time entanglement 

      Strekalov, D. V.; Pittman, T.B.; Sergienko, A. V.; Shih, Y. H.; Kwiat, P. G. (American Physical Society (APS), 1996-07-01)
      We report a two-photon interference experiment that realizes a postselection-free test of Bell's inequality based on energy-time entanglement. In contrast with all previous experiments of this type, the employed entangled ...
    • Can Two-Photon Interference be Considered the Interference of Two Photons? 

      Pittman, T. B.; Strekalov, D. V.; Migdall, A.; Rubin, M. H.; Sergienko, A. V.; Shih, Y. H. (American Physical Society (APS), 1996-09-02)
      We report on a “postponed compensation” experiment in which the observed two-photon entangled state interference cannot be pictured in terms of the overlap of the two individual photon wave packets of a parametric ...
    • Quantum logic using photon-exchange interactions 

      Franson, J.D.; Pittman, T.B. (OSA Publishing, 2000-05)
      Nonlinear optical effects at the two-photon level are usually negligible because of the weak electric field associated with a single photon.
    • Search for the Identification of 3EG J1835+5918: Evidence for a New Type of High-Energy Gamma-Ray Source 

      Mirabal, N.; Halpern, J. P.; Eracleous, M.; Becker, R. H. (IOP, 2000-05-10)
      The EGRET source 3EG J1835+5918 is the brightest and most accurately positioned of the as-yet unidentified high-energy γ-ray sources at high Galactic latitude (ℓ,b = 89°,25°). We present a multiwavelength study of the ...
    • GRB 991216 Joins the Jet Set: Discovery and Monitoring of its Optical Afterglow 

      Halpern, J. P.; Uglesich, R.; Mirabal, N.; Kassin, S.; Thorstensen, J.; Keel, W. C.; Diercks, A.; Bloom, J. S.; Harrison, F.; Mattox, J.; Eracleous, M. (IOP, 2000-06-15)
      The optical light curve of the energetic γ-ray burst GRB 991216 is consistent with jetlike behavior in which a power-law decay steepens from t⁻¹·²²⁺⁰·⁰⁴ at early times to t⁻¹·⁵³⁺⁰·⁰⁵ in a gradual transition at around 2 ...
    • A Neutron Star Identification for the High-Energy Gamma-Ray Source 3EG J1835+5918 Detected in the ROSAT All-Sky Survey 

      Mirabal, N.; Halpern, J. P. (IOP, 2001-01-24)
      In the error box of 3EG J1835+5918, the brightest as-yet unidentified EGRET source at intermediate Galactic latitude, we find a weak, ultrasoft X-ray source at energies E < 0.3 keV in the ROSAT All-Sky Survey. Deep optical ...
    • Multicolor Observations of the GRB 000926 Afterglow 

      Price, P. A.; Harrison, F. A.; Galama, T. J.; Reichart, D. E.; Axelrod, T. S.; Berger, E.; Bloom, J. S.; Busche, J.; Cline, T.; Diercks, A.; Djorgovski, S. G.; Frail, D. A.; Gal-Yam, A.; Halpern, J.; Holtzman, J. A.; Hunt, M.; Hurley, K.; Jacoby, B.; Kimble, R.; Kulkarni, S. R.; Mirabal, N.; Morrison, G.; Ofek, E.; Pevunova, O.; Sari, R.; Schmidt, B. P.; Turnshek, D.; Yost, S. (IOP, 2001-02-26)
      We present multicolor light curves of the optical afterglow of gamma-ray burst (GRB) 000926. Beginning ~1.5 days after the burst, the light curves of this GRB steepen measurably. The existence of such achromatic breaks is ...
    • Tidal Satellite Perturbations and the Lense-Thirring Effect 

      Iorio, Lorenzo; Pavlis, Erricos C. (The Geodetic Society of Japan, 2001-03-25)
    • A Dozen Years of Temperature Observations at the Summit: Central Greenland Automatic Weather Stations 1987–99 

      Shuman, Christopher; Steffen, Konrad; Box, Jason E.; Stearns, Charles R. (AMS, 2001-04-01)
      On 4 May 1987, the first automatic weather station (AWS) near the summit of the Greenland Ice Sheet began transmitting data. Air temperature records from this site, AWS Cathy, as well as nearby AWS at the Greenland Ice ...
    • GRB 000418: A Hidden Jet Revealed 

      Berger, E.; Diercks, A.; Frail, D. A.; Kulkarni, S. R.; Bloom, J. S.; Sari, R.; Halpern, J.; Mirabal, N.; Taylor, G. B.; Hurley, K.; Pooley, G.; Becker, K. M.; Wagner, R. M.; Terndrup, D. M.; Statler, T.; Wik, D. R.; Mazets, E.; Cline, T. (IOP, 2001-04-05)
      We report on optical, near-infrared, and centimeter radio observations of GRB 000418 that allow us to follow the evolution of the afterglow from 2 to 200 days after the γ-ray burst (GRB). In modeling these broadband data, ...
    • Decadal-Length Composite Inland West Antarctic Temperature Records 

      Shuman, Christopher A.; Stearns, Charles R. (AMS, 2001-05-01)
      Decadal-length, daily average, temperature records have been generated for four inland West Antarctic sites by combining automatic weather station (AWS) and satellite passive microwave brightness temperature records. These ...
    • Probabilistic quantum logic operations using polarizing beam splitters 

      Pittman, T. B.; Jacobs, B. C.; Franson, J. D. (American Physical Society (APS), 2001-11-16)
      It has previously been shown that probabilistic quantum logic operations may be performed using linear optical elements, additional photons (ancilla), and post-selection based on the output of single-photon detectors. Here ...
    • Mapping Greenland accumulation rates using observations of thermal emission at 4.5-cm wavelength 

      Winebrenner, Dale P.; Arthern, Robert J.; Shuman, Christopher A. (AGU, 2001-12-01)
      Accurate predictions of sea level rise over the coming century will require improved knowledge of the processes controlling accumulation on the great ice sheets. The sparsity of accumulation rate observations, both temporally ...
    • Multiyear accumulation and temperature history near the North Greenland Ice Core Project site, north central Greenland 

      Shuman, Christopher; Bromwich, D.H.; Kipfstuhl, J.; Schwager, M. (AGU, 2001-12-27)
      This paper presents a comparison of two independent methods of estimating subseasonal accumulation across the interior of Greenland. These methods, high-resolution snow pit studies and atmospheric modeling, have differing ...
    • Is the EGRET Source 3EG J1621+8203 the Radio Galaxy NGC 6251? 

      Mukherjee, R.; Halpern, J.; Mirabal, N.; Gotthelf, E. V. (IOP, 2002-04-03)
      We discuss the nature of the unidentified EGRET source 3EG J1621+8203. In an effort to identify the gamma-ray source, we have examined X-ray images of the field from ROSAT PSPC, ROSAT HRI, and ASCA GIS. Of the several faint ...
    • Improved mapping functions for atmospheric refraction correction in SLR 

      Mendes, V. B.; Prates, G.; Pavlis, Erricos C.; Pavlis, D.E.; Langley, R. B. (AGU Pubication, 2002-05-24)
      We present two new mapping functions (MFs) to model the elevation angle dependence of the atmospheric delay for satellite laser ranging (SLR) data analysis. The new MFs were derived from ray tracing through a set of data ...
    • Multiwavelength Searches of Unidentified EGRET Sources 

      Mirabal, N.; Halpern, J.; Mukherjee, R.; Gotthelf, E.; Camilo, F. (2002-05-28)
      3EG J1835+5918 is the brightest of the so-called unidentified EGRET sources at intermediate galactic latitude (l,b)=(89,25). We obtained complete radio, optical, and X-ray coverage of its error box, discovering a faint ...
    • The Next Geminga: Deep Multiwavelength Observations of a Neutron Star Identified with 3EG J1835+5918 

      Halpern, J. P.; Gotthelf, E. V.; Mirabal, N.; Camilo, F. (IOP, 2002-06-02)
      We describe Chandra, Hubble Space Telescope (HST), and radio observations that reveal a radio-quiet but magnetospherically active neutron star in the error circle of the high-energy γ-ray source 3EG J1835+5918, the brightest ...