A5044617944- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- SAS software applications and methods
- Pulsars and Gravitational Waves Research
- Historical Astronomy and Related Studies
- History and Developments in Astronomy
- Astrophysics and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Particle Detector Development and Performance
- Planetary Science and Exploration
- Historical and Architectural Studies
- Geophysics and Gravity Measurements
- Statistical and numerical algorithms
- Nuclear Physics and Applications
- Historical, Religious, and Philosophical Studies
- Laser-Plasma Interactions and Diagnostics
- Medical Imaging Techniques and Applications
- Astrophysics and Star Formation Studies
- High-pressure geophysics and materials
- Adaptive optics and wavefront sensing
- CCD and CMOS Imaging Sensors
Louisiana State University
2016-2025
University of California, Santa Barbara
2009
The University of Texas at Austin
2001-2005
Yale University
1995-2004
Whitney Museum of American Art
1998-2000
Cerro Tololo Inter-American Observatory
1995-1998
U.S. National Science Foundation
1996-1998
Goddard Space Flight Center
1987-1996
Association of Universities For Research In Astronomy
1995
United States Naval Observatory
1994
We report measurements of the mass density, ΩM, and cosmological-constant energy ΩΛ, universe based on analysis 42 type Ia supernovae discovered by Supernova Cosmology Project. The magnitude-redshift data for these supernovae, at redshifts between 0.18 0.83, are fitted jointly with a set from Calán/Tololo Survey, below 0.1, to yield values cosmological parameters. All supernova peak magnitudes standardized using SN light-curve width-luminosity relation. measurement yields joint probability...
The Swift mission, scheduled for launch in 2004, is a multiwavelength observatory gamma-ray burst (GRB) astronomy. It first-of-its-kind autonomous rapid-slewing satellite transient astronomy and pioneers the way future rapid-reaction missions. will be far more powerful than any previous GRB observing 100 bursts yr-1 performing detailed X-ray UV/optical afterglow observations spanning timescales from 1 minute to several days after burst. objectives are (1) determine origin of GRBs, (2)...
We report measurements of ΩM, ΩΛ, and w from 11 supernovae (SNe) at z = 0.36-0.86 with high-quality light curves measured using WFPC2 on the Hubble Space Telescope (HST). This is an independent set high-redshift SNe that confirms previous SN evidence for accelerating universe. The available photometry make it possible these alone to provide cosmological parameters comparable in statistical weight results. Combined earlier Supernova Cosmology Project data, new yield a measurement mass density...
R-band intensity measurements along the light curve of Type Ia supernovae (SNe Ia) discovered by Supernova Cosmology Project (SCP) are fitted in brightness to templates allowing a free parameter time-axis width factor w ≡ s(1 + z). The data points then individually aligned time axis, normalized, and K-corrected back rest frame, after which nearly 1300 normalized found lie on well-determined common rest-frame B-band curve, we call "composite curve." same procedure is applied 18 low-redshift...
One of the few ways to measure properties Dark Energy is extend Hubble daigram (HD) higher redshifts with Gamma-Ray Bursts (GRBs). GRBs have at least five (their spectral lag, variability, peak photon energy, time jet break, and minimum rise time) which correlations luminosity varying quality. In this paper, I construct a GRB HD 69 over redshift range 0.17 >6, half bursts having larger than 1.7. This paper uses 3.6 times as many 12.7 indicators any previous work. For gravitational lensing...
Short duration flares are well known to occur on cool main-sequence stars as many types of `exotic' stars. Ordinary usually pictured being static time scales millions or billions years. Our sun has occasional involving up $\sim 10^{31}$ ergs which produce optical brightenings too small in amplitude be detected disk-integrated brightness. However, we identify nine cases superflares $10^{33}$ $10^{38}$ normal solar-type That is, these near the main-sequence, spectral class from F8 G8, single...
I collect virtually all photometry of the ten known galactic recurrent novae (RNe) and their 37 eruptions. This consists my modern measures nearly archival plates (providing only data for half eruptions), own 10,000 CCD magnitudes from 1987 to present in quiescence seven RNe), over 140,000 visual magnitude estimates recorded by amateur astronomers (who discovered small scattering literature. From this, produce various uniform products; (1) BVRIJHK comparison star BV sequences cover entire...
We present multicolor optical and two-frequency radio observations of the bright BeppoSAX event GRB 990510. Neither well-sampled decay nor are consistent with simple spherical afterglow models. The achromatic steepening in band early afterglow, which both occur at t ~ 1 day, evidence for hydrodynamical evolution source can be most easily interpreted by models gamma-ray burst ejecta collimated a jet. Employing jet model to explain observations, we derive opening angle θ0 = 0.08(n/1 cm-3)1/8,...
view Abstract Citations (248) References (41) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS BATSE Observations of Gamma-Ray Burst Spectra. II. Peak Energy Evolution in Bright, Long Bursts Ford, L. A. ; Band, D. Matteson, J. Briggs, M. S. Pendleton, G. N. Preece, R. Paciesas, W. Teegarden, B. Palmer, Schaefer, E. Cline, T. Fishman, Kouveliotou, C. Meegan, Wilson, Lestrade, P. We investigate spectral evolution 37 bright, long gamma-ray bursts observed with...
We have measured the periods and light curves of 148 RR Lyrae variables from V = 13.5 to 19.7 first 100 deg2 Quasar Equatorial Survey Team survey. Approximately 55% these stars belong clump detected earlier by Sloan Digital Sky Survey. According our measurements, this feature has ~10 times background density halo stars, spans at least 375 35 in α δ (≥30 ≥3 kpc), lies ~50 kpc Sun, a depth along line sight ~5 (1 σ). These properties are consistent with recent models that suggest it is tidal...
We present a catalog of 93 very-well-observed nova light curves. The curves were constructed from 229,796 individual measured magnitudes, with the median coverage extending to 8.0 mag below peak and 26% following eruption all way quiescence. Our time-binned are presented in figures as complete tabulations. also calculate tabulate many properties about curves, including magnitudes dates, times decline by 2, 3, 6, 9 maximum, time until brightness returns quiescence, quiescent magnitude, power...
Explosive astrophysical events at high redshift can be used to place severe limits on the fractional variation in speed of light with frequency ( $\ensuremath{\Delta}c/c$), photon mass ${m}_{\ensuremath{\gamma}}$), and energy scale quantum gravity ${E}_{\mathrm{QG}}$). I find $\ensuremath{\Delta}c/c<6.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}21}$ based simultaneous arrival a flare GRB 930229 rise time $220\ifmmode\pm\else\textpm\fi{}30\ensuremath{\mu}\mathrm{s}$ for photons 30...
This presentation reports on first evidence for a low-mass-density/positive-cosmological-constant universe that will expand forever, based observations of set 40 high-redshift supernovae. The experimental strategy, data sets, and analysis techniques are described. More extensive analyses these results with some additional methods presented in the more recent LBNL report #41801 (Perlmutter et al., 1998; accepted publication Ap.J.), astro-ph/9812133 . Lawrence Berkeley National Laboratory...
In this paper, measurements of the sky brightness from 2800-m level Mauna Kea are reported. addition, a model is presented for predicting moonlight as function moon's phase, zenith distance moon, position, angular separation moon and local extinction coefficient. The equations can be quickly calculated on pocket calculator. A comparison with lunar data some Russian solar shows accuracy predictions to range 8 percent 23 percent.
Stellar flares with 102-107 times more energy than the largest solar flare have recently been detected from nine normal F and G main-sequence stars by Schaefer, King, Deliyannis. These superflares durations of hours to days are visible at least X-ray optical frequencies. The absence world-spanning aurorae in historical records anomalous extinctions geological record indicates that our Sun likely does not suffer superflares. In seeking explain this new phenomenon, we struck its similarity...
We have measured the solar phase curves in B, V, and I for 18 trans-Neptunian objects (TNOs), 7 Centaurs, Nereid determined rotation 10 of these targets. For each body we made ∼100 observations uniformly spread over entire visible range. find that all targets except linear at small angles (0.1°-2.0°) with widely varying coefficients (0.0-0.4 mag deg-1). At 2°-3°, Centaurs (54598) Bienor (32532) Thereus flatten. The recently discovered Pluto-scale bodies (2005 FY9, 2003 EL61, UB313—now known...
We report on a complete set of early optical afterglows gamma-ray bursts (GRBs) obtained with the Robotic Optical Transient Search Experiment (ROTSE-III) telescope network from 2005 March through 2007 June. This is comprised 12 and Swift/X-Ray Telescope observations, median ROTSE-III response time 45 s after start γ-ray emission (8 GCN notice time). These span 4 orders magnitude in luminosity, contemporaneous X-ray detections allow multi-wavelength spectral analysis. Excluding flares,...
The Gaia spacecraft has just released a large set of parallaxes, including 41 novae for which the fractional error is <30 per cent. I have used these to evaluate accuracy and bias many prior methods getting nova distances. best geometrical parallaxes from Hubble Space Telescope four novae, although real bars are 3× larger than stated. canonical method distances been expansion shells, but this found 1σ uncertainty 0.95 mag in distance modulus, quoted on average 3.6× worse advertised....
KIC8462852 is a completely-ordinary F3 main sequence star, except that the light curve from Kepler shows episodes of unique and inexplicable day-long dips with up to 20% dimming. Here, I provide 1338 Johnson B-band magnitudes 1890 1989 taken archival photographic plates at Harvard. displays secular dimming an average rate 0.164+-0.013 per century. From early-1890s late-1980s, faded by 0.193+-0.030 mag. The decline not artifact because nearby check stars have closely flat curves. This...
ABSTRACT I derive the overall best distances for all 402 known Galactic novae, and collect their many properties. The centrepiece is 74 novae with accurate parallaxes from new Gaia data release. For needed priors, have collected 171 based on old methods (including expansion extinction distances). Further, V-magnitudes at peak measures, so as to produce absolute magnitudes then a crude distance prior. recognized that 41 per cent of are concentrated in bulge, 68 these &lt;5.4° Centre, 165...
ABSTRACT T CrB is one of the most-famous and brightest novae known, a recurrent nova with prior eruptions in 1866 1946 that peak at V = 2.0. I have constructed light curves spanning 1842–2022 213 730 magnitudes, where B magnitudes are fully corrected to Johnson system. These first reveal unique complex high-state (with 20× higher accretion rate than normal low-state) stretching from −10 +9 yr after eruption, punctuated deep pre-eruption dip (apparently dust formation slow mass ejection)...
Gamma-ray bursts (GRBs) are tremendous explosions visible across most of the Universe, certainly out to redshifts z=4.5 and likely z~10. Recently, GRBs have been found a roughly constant explosive energy as well two luminosity indicators (the spectral lag time variability) that can be used derive burst's distance from gamma-ray light curve alone. There currently exists enough information calibrate distances independent for nine bursts. From these, GRB Hubble diagram constructed, where...