382 research outputs found
Supreme Court Voting Behavior - 2003 Term
The 2003 Term, for the second year, notes a liberal trend across a majority of the Tables of this Study. The voting behavior of individual Justices in 2003 was somewhat more stable this Term in that individual departures from past voting behaviors were less pronounced than in 2002. Nevertheless, the Study still demonstrates continuing instability in the voting behavior of individual Justices. This Term, statistically significant departures from past behavior by at least five Members of the Court are present on six Tables. This might suggest that the voting behavior of the Justices on these Tables is in transition, although the often-small statistical samples reported on many of these Tables also suggests caution in making (or relying upon) this inference. Bloc voting continues to control the outcome of a substantial number of the most controversial questions presented to the Court. But, as noted in the past few Studies, the voting power of conservative voting blocs seems to be losing steam. Justice O\u27Connor maintained her position as the Member of the Court most likely to cast the key swing-vote in closely divided opinions. The Study also demonstrates that Justice O\u27Connor\u27s voting behavior in state criminal cases has been a reliable indicator of the outcome of Majority Opinions in this category for a number of years. Her absence might alter decisional outcomes, not only in state criminal cases, but in the often-important cases decided by five-to-four votes of the Court
The Robotic Super-LOTIS Telescope: Results & Future Plans
We provide an overview of the robotic Super-LOTIS (Livermore Optical Transient Imaging System) telescope and present results from gamma-ray burst (GRB) afterglow observations using Super-LOTIS and other Steward Observatory telescopes. The 0.6-m Super-LOTIS telescope is a fully robotic system dedicated to the measurement of prompt and early time optical emission from GRBs. The system began routine operations from its Steward Observatory site atop Kitt Peak in April 2000 and currently operates every clear night. The telescope is instrumented with an optical CCD camera and a four position filter wheel. It is capable of observing Swift Burst Alert Telescope (BAT) error boxes as early or earlier than the Swift UV/Optical Telescope (UVOT). Super-LOTIS complements the UVOT observations by providing early R- and I-band imaging. We also use the suite of Steward Observatory telescopes including the 1.6-m Kuiper, the 2.3-m Bok, the 6.5-m MMT, and the 8.4-m Large Binocular Telescope to perform follow-up optical and near infrared observations of GRB afterglows. These follow-up observations have traditionally required human intervention but we are currently working to automate the 1.6-m Kuiper telescope to minimize its response time
The bright optical/NIR afterglow of the faint GRB 080710 - Evidence for a jet viewed off axis
We investigate the optical/near-infrared light curve of the afterglow of GRB
080710 in the context of rising afterglows. Optical and near-infrared
photometry was performed using the seven channel imager GROND and the
Tautenburg Schmidt telescope. X-ray data were provided by the X-ray Telescope
onboard the Swift satellite. The optical/NIR light curve of the afterglow of
GRB 080710 is dominated by an initial increase in brightness, which smoothly
turns over into a shallow power law decay. The initially rising achromatic
light curve of the afterglow of GRB 080710 can be accounted for with a model of
a burst viewed off-axis or a single jet in its pre deceleration phase and in an
on-axis geometry. An unified picture of the afterglow light curve and prompt
emission properties can be obtained with an off-axis geometry, suggesting that
late and shallow rising optical light curves of GRB afterglows might be
produced by geometric effects.Comment: 9 pages, 4 figures, accepted by A and
Evidence for Supernova-Synthesised Dust from the Rising Afterglow of GRB 071025 at z~5
We present observations and analysis of the broadband afterglow of Swift GRB
071025. Using optical and infrared (RIYJHK) photometry, we derive a photometric
redshift of 4.4 < z < 5.2; at this redshift our simultaneous multicolour
observations begin at ~30 s after the GRB trigger in the host frame and during
the initial rising phase of the afterglow. We associate the light curve peak at
580 s in the observer frame with the formation of the forward shock, giving an
estimate of the initial Lorentz factor Gamma_0 ~ 200. The red spectral energy
distribution (even in regions not affected by the Lyman-alpha break) provides
secure evidence of a large dust column. However, the inferred extinction curve
shows a prominent flat component between 2000-3000 Angstroms in the rest-frame,
inconsistent with any locally observed template but well-fit by models of dust
formed by supernovae. Time-dependent fits to the extinction profile reveal no
evidence of dust destruction and limit the decrease in the extinction column to
Delta A_3000 < 0.54 mag after t = 50 s in the rest frame. Our observations
provide evidence of a transition in dust properties at z~5, in agreement with
studies of high-z quasars, and suggest that SN-formed dust continues to
dominate the opacity of typical galaxies at this redshift.Comment: Resubmitted to MNRAS following referee report. Contains additional
figure and some extra analysis/discussio
Processing CCD Images to Detect Transits of Earth-Sized Planets: Maximizing Sensitivity While Achieving Reasonable Downlink Requirements
We have performed end-to-end laboratory and numerical simulations to demonstrate the capability of differential photometry under realistic operating conditions to detect transits of Earth-sized planets orbiting solar-like stars. Data acquisition and processing were conducted using the same methods planned for the proposed Kepler Mission. These included performing aperture photometry on large-format CCD images of an artificial star fields obtained without a shutter at a readout rate of 1 megapixel/sec, detecting and removing cosmic rays from individual exposures and making the necessary corrections for nonlinearity and shutterless operation in the absence of darks. We will discuss the image processing tasks performed `on-board' the simulated spacecraft, which yielded raw photometry and ancillary data used to monitor and correct for systematic effects, and the data processing and analysis tasks conducted to obtain lightcurves from the raw data and characterize the detectability of transits. The laboratory results are discussed along with the results of a numerical simulation carried out in parallel with the laboratory simulation. These two simulations demonstrate that a system-level differential photometric precision of 10-5 on five- hour intervals can be achieved under realistic conditions
The Rapidly Flaring Afterglow of the Very Bright and Energetic GRB 070125
We report on multiwavelength observations, ranging from X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O i,Si ii,and C iv, implying a likely redshift of z ¼1:547. The well-sampled light curves, in particular from 0.5 to 4 days after the burst, suggest a jet break at 3.7 days, corresponding to a jet opening angle of 8000 s.The evolution of the afterglow light curve is achromatic at all times.Late-time observationsof the afterglow do not show evidence for emission from an underlying host galaxy or supernova. Any host galaxy would be subluminous, consistent with current GRB host galaxy samples. Evidence for strong Mg ii absorption features is not found, which is perhaps surprising in view of the relatively high redshift of this burst and the high likelihood for such features along GRB-selected lines of sight
A photometric redshift of for the \agile GRB 080514B
Aims: The AGILE gamma-ray burst GRB 080514B is the first burst with detected
emission above 30 MeV and an optical afterglow. However, no spectroscopic
redshift for this burst is known.
Methods: We compiled ground-based photometric optical/NIR and millimeter data
from several observatories, including the multi-channel imager GROND, as well
as ultraviolet \swift UVOT and X-ray XRT observations. The spectral energy
distribution of the optical/NIR afterglow shows a sharp drop in the \swift UVOT
UV filters that can be utilized for the estimation of a redshift.
Results: Fitting the SED from the \swift UVOT band to the band, we
estimate a photometric redshift of , consistent with the
pseudo redshift reported by Pelangeon & Atteia (2008) based on the gamma-ray
data.
Conclusions: The afterglow properties of GRB 080514B do not differ from those
exhibited by the global sample of long bursts, supporting the view that
afterglow properties are basically independent of prompt emission properties.Comment: submitted to A&A letter
Optical and near-infrared follow-up observations of four Fermi/LAT GRBs : Redshifts, afterglows, energetics and host galaxies
Fermi can measure the spectral properties of gamma-ray bursts over a very
large energy range and is opening a new window on the prompt emission of these
energetic events. Localizations by the instruments on Fermi in combination with
follow-up by Swift provide accurate positions for observations at longer
wavelengths leading to the determination of redshifts, the true energy budget,
host galaxy properties and facilitate comparison with pre-Fermi bursts.
Multi-wavelength follow-up observations were performed on the afterglows of
four bursts with high energy emission detected by Fermi/LAT : GRB090323,
GRB090328, GRB090510 and GRB090902B. They were obtained in the
optical/near-infrared bands with GROND mounted at the MPG/ESO 2.2m telescope
and additionally of GRB090323 in the optical with the 2 m telescope in
Tautenburg, Germany. Three of the events are classified as long bursts while
GRB090510 is a well localized short GRB with GeV emission. In addition, host
galaxies were detected for three of the four bursts. Spectroscopic follow-up
was initiated with the VLT for GRB090328 and GRB090510. The afterglow
observations in 7 bands are presented for all bursts and their host galaxies
are investigated. Knowledge of the distance and the local dust extinction
enables comparison of the afterglows of LAT-detected GRBs with the general
sample. The spectroscopic redshifts of GRB090328 and GRB090510 were determined
to be z=0.7354+/-0.0003 and z=0.903 +/- 0.001 and dust corrected star-formation
rates of 4.8 Mdot yr^-1 and 0.60 M_dot yr^-1 were derived for their host
galaxies, respectively. The afterglows of long bursts exhibit power-law decay
indices alpha from less than 1 to ~2.3 and spectral indices (beta) values from
0.65 to ~1.2 which are fairly standard for GRB afterglows. Constraints are
placed on the jet half opening angles of less than 2.1 deg to greater than 6.4
deg which allows limits to be placed on the beaming corrected energies. These
range from less than 5x10^50 erg to the one of the highest values ever
recorded, greater than 2.2x10^52 erg for GRB090902B, and are not consistent
with a standard candle. The extremely energetic long Fermi bursts have optical
afterglows which lie in the top half of the brightness distribution of all
optical afterglows detected in the Swift era or even in the top 5% if
incompleteness is considered. The properties of the host galaxies of these LAT
detected bursts in terms of extinction, star formation rates and masses do not
appear to differ from previous samples.Comment: Accepted for publication in Astronomy and Astrophysics. 16 pages, 14
figures
The Rapidly Flaring Afterglow of the Very Bright and Energetic GRB 070125
We report on multiwavelength observations, ranging from X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O I, Si II, and C IV, implying a likely redshift of z = 1.547. The well-sampled light curves, in particular from 0.5 to 4 days after the burst, suggest a jet break at 3.7 days, corresponding to a jet opening angle of ~7.0°, and implying an intrinsic GRB energy in the 1-10,000 keV band of around Eγ = (6.3–6.9) × 1051 ergs (based on the fluences measured by the gamma-ray detectors of the IPN). GRB 070125 is among the brightest afterglows observed to date. The SED implies a host extinction of AV \u3c 0.9 mag . Two rebrightening episodes are observed, one with excellent time coverage, showing an increase in flux of 56% in ~8000 s. The evolution of the afterglow light curve is achromatic at all times. Late-time observations of the afterglow do not show evidence for emission from an underlying host galaxy or supernova. Any host galaxy would be subluminous, consistent with current GRB host galaxy samples. Evidence for strong Mg II absorption features is not found, which is perhaps surprising in view of the relatively high redshift of this burst and the high likelihood for such features along GRB-selected lines of sight
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