3,365 research outputs found
Discovery of a supernova associated with GRB 031203: SMARTS Optical-Infrared Lightcurves from 0.2 to 92 days
Optical and infrared monitoring of the afterglow site of gamma-ray burst
(GRB) 031203 has revealed a brightening source embedded in the host galaxy,
which we attribute to the presence of a supernova (SN) related to the GRB ("SN
031203"). We present details of the discovery and evolution of SN 031203 from
0.2 to 92 days after the GRB, derived from SMARTS consortium photometry in I
and J bands. A template type Ic lightcurve, constructed from SN 1998bw
photometry, is consistent with the peak brightness of SN 031203 although the
lightcurves are not identical. Differential astrometry reveals that the SN, and
hence the GRB, occurred less than 300 h_71^-1 pc (3-sigma) from the apparent
galaxy center. The peak of the supernova is brighter than the optical afterglow
suggesting that this source is intermediate between a strong GRB and a
supernova.Comment: 11 pages, 3 figures, submitted to ApJ Letter
Fuzzy Spatial Querying with Inexact Inference
The issue of spatial querying accuracy has been viewed as critical to the successful implementation and long-term viability of the GIS technology. In order to improve the spatial querying accuracy and quality, the problems associated with the areas of fuzziness and uncertainty are of great concern in the spatial database community. There has been a strong demand to provide approaches that deal with inaccuracy and uncertainty in GIS. In this paper, we are dedicated to develop an approach that can perform fuzzy spatial querying under uncertainty. An inexact inferring strategy is investigated. The study shows that the fuzzy set and the certainty factor can work together to deal with spatial querying. Querying examples implemented by FuzzyClips are also provided
GRB 050408: An Atypical Gamma-Ray Burst as a Probe of an Atypical Galactic Environment
The bright GRB 050408 was localized by HETE-II near local midnight, enabling
an impressive ground-based followup effort as well as space-based followup from
Swift. The Swift data from the X-Ray Telescope (XRT) and our own optical
photometry and spectrum of the afterglow provide the cornerstone for our
analysis. Under the traditional assumption that the visible waveband was above
the peak synchrotron frequency and below the cooling frequency, the optical
photometry from 0.03 to 5.03 days show an afterglow decay corresponding to an
electron energy index of p_lc = 2.05 +/- 0.04, without a jet break as suggested
by others. A break is seen in the X-ray data at early times (at ~12600 sec
after the GRB). The spectral slope of the optical spectrum is consistent with
p_lc assuming a host-galaxy extinction of A_V = 1.18 mag. The optical-NIR
broadband spectrum is also consistent with p = 2.05, but prefers A_V = 0.57
mag. The X-ray afterglow shows a break at 1.26 x 10^4 sec, which may be the
result of a refreshed shock. This burst stands out in that the optical and
X-ray data suggest a large H I column density of N_HI ~ 10^22 cm^-2; it is very
likely a damped Lyman alpha system and so the faintness of the host galaxy (M_V
> -18 mag) is noteworthy. Moreover, we detect extraordinarily strong Ti II
absorption lines with a column density through the GRB host that exceeds the
largest values observed for the Milky Way by an order of magnitude.
Furthermore, the Ti II equivalent width is in the top 1% of Mg II
absorption-selected QSOs. This suggests that the large-scale environment of GRB
050408 has significantly lower Ti depletion than the Milky Way and a large
velocity width (delta v > 200 km/s).Comment: ApJ submitte
How was it for you? Experiences of participatory design in the UK health service
Improving co-design methods implies that we need to understand those methods, paying attention to not only the effect of method choices on design outcomes, but also how methods affect the people involved in co-design. In this article, we explore participants' experiences from a year-long participatory health service design project to develop ‘Better Outpatient Services for Older People’. The project followed a defined method called experience-based design (EBD), which represented the state of the art in participatory service design within the UK National Health Service. A sample of participants in the project took part in semi-structured interviews reflecting on their involvement in and their feelings about the project. Our findings suggest that the EBD method that we employed was successful in establishing positive working relationships among the different groups of stakeholders (staff, patients, carers, advocates and design researchers), although conflicts remained throughout the project. Participants' experiences highlighted issues of wider relevance in such participatory design: cost versus benefit, sense of project momentum, locus of control, and assumptions about how change takes place in a complex environment. We propose tactics for dealing with these issues that inform the future development of techniques in user-centred healthcare design
Far Ultraviolet Absolute Flux of alpha Virginis
We present the far ultraviolet spectrum of alpha Virginis taken with EURD
spectrograph on-board MINISAT-01. The spectral range covered is from ~900 to
1080 A with 5 A spectral resolution. We have fitted Kurucz models to IUE
spectra of alpha Vir and compared the extension of the model to our wavelengths
with EURD data. This comparison shows that EURD fluxes are consistent with the
prediction of the model within 20-30%, depending on the reddening assumed. EURD
fluxes are consistent with Voyager observations but are ~60% higher than most
previous rocket observations of alpha Vir.Comment: 13 pages, 4 figures. Submitted to The Astrophysical Journa
Probing Kilonova Ejecta Properties Using a Catalog of Short Gamma-Ray Burst Observations
The discovery of GW170817 and GRB 170817A in tandem with AT 2017gfo cemented
the connection between neutron star mergers, short gamma-ray bursts (GRBs), and
kilonovae. To investigate short GRB observations in the context of diverse
kilonova behavior, we present a comprehensive optical and near-infrared (NIR)
catalog of 85 bursts discovered over 2005-2020 on timescales of
days. The sample includes previously unpublished observations of 23 bursts, and
encompasses both detections and deep upper limits. We identify 11.8% and 15.3%
of short GRBs in our catalog with upper limits that probe luminosities lower
than those of AT 2017gfo and a fiducial NSBH kilonovae model (for pole-on
orientations), respectively. We quantify the ejecta masses allowed by the
deepest limits in our catalog, constraining blue and `extremely blue' kilonova
components of 14.1% of bursts to . The
sample of short GRBs is not particularly constraining for red kilonova
components. Motivated by the large catalog as well as model predictions of
diverse kilonova behavior, we investigate altered search strategies for future
follow-up to short GRBs. We find that ground-based optical and NIR observations
on timescales of days can play a significant role in constraining
more diverse outcomes. We expect future short GRB follow up efforts, such as
from the {\it James Webb Space Telescope}, to expand the reach of kilonova
detectability to redshifts of .Comment: 33 pages, 7 figures, 3 tables. Submitted to Ap
Inclusion of Experimental Information in First Principles Modeling of Materials
We propose a novel approach to model amorphous materials using a first
principles density functional method while simultaneously enforcing agreement
with selected experimental data. We illustrate our method with applications to
amorphous silicon and glassy GeSe. The structural, vibrational and
electronic properties of the models are found to be in agreement with
experimental results. The method is general and can be extended to other
complex materials.Comment: 11 pages, 8 PostScript figures, submitted to J. Phys.: Condens.
Matter in honor of Mike Thorpe's 60th birthda
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