Showing papers by "E. E. Fenimore published in 2004"
Goddard Space Flight Center1, University of Milan2, Brera Astronomical Observatory3, University College London4, Pennsylvania State University5, University of Leicester6, Sonoma State University7, University of California, Berkeley8, Universities Space Research Association9, National Research Council10, University of Southampton11, Los Alamos National Laboratory12, National Radio Astronomy Observatory13, Space Telescope Science Institute14, Max Planck Society15, California Institute of Technology16, University of Texas at Austin17, French Alternative Energies and Atomic Energy Commission18, University of Toronto19, University of Maryland, College Park20, Princeton University21, Lawrence Livermore National Laboratory22, University of Cambridge23, University of California, Santa Barbara24, Rice University25, University of Tokyo26, Saitama University27, University of Florence28
TL;DR: The Swift mission as discussed by the authors is a multi-wavelength observatory for gamma-ray burst (GRB) astronomy, which is a first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions.
Abstract: The Swift mission, scheduled for launch in 2004, is a multiwavelength observatory for gamma-ray burst (GRB) astronomy. It is a first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions. It will be far more powerful than any previous GRB mission, observing more than 100 bursts yr � 1 and performing detailed X-ray and UV/optical afterglow observations spanning timescales from 1 minute to several days after the burst. The objectives are to (1) determine the origin of GRBs, (2) classify GRBs and search for new types, (3) study the interaction of the ultrarelativistic outflows of GRBs with their surrounding medium, and (4) use GRBs to study the early universe out to z >10. The mission is being developed by a NASA-led international collaboration. It will carry three instruments: a newgeneration wide-field gamma-ray (15‐150 keV) detector that will detect bursts, calculate 1 0 ‐4 0 positions, and trigger autonomous spacecraft slews; a narrow-field X-ray telescope that will give 5 00 positions and perform spectroscopy in the 0.2‐10 keV band; and a narrow-field UV/optical telescope that will operate in the 170‐ 600 nm band and provide 0B3 positions and optical finding charts. Redshift determinations will be made for most bursts. In addition to the primary GRB science, the mission will perform a hard X-ray survey to a sensitivity of � 1m crab (� 2;10 � 11 ergs cm � 2 s � 1 in the 15‐150 keV band), more than an order of magnitude better than HEAO 1 A-4. A flexible data and operations system will allow rapid follow-up observations of all types of
3,753 citations
Los Alamos National Laboratory1, Tokyo Institute of Technology2, University of Chicago3, Massachusetts Institute of Technology4, Aoyama Gakuin University5, National Space Development Agency of Japan6, New Mexico State University7, University of California, Berkeley8, Centre national de la recherche scientifique9, University of California, Santa Cruz10, Goddard Space Flight Center11, National Institute for Space Research12, Tata Institute of Fundamental Research13
TL;DR: In this paper, the authors show that the properties of X-ray flash XRF 020903 are consistent with the relation between the fluences S(7-30 keV) and S(30-400 keV), found by Barraud et al. for GRBs.
Abstract: We report High Energy Transient Explorer 2 (HETE-2) Wide Field X-Ray Monitor/French Gamma Telescope observations of the X-ray flash XRF 020903. This event was extremely soft: the ratio log(SX/Sγ) = 0.7, where SX and Sγ are the fluences in the 2-30 and 30-400 keV energy bands, is the most extreme value observed so far by HETE-2. In addition, the spectrum has an observed peak energy of E < 5.0 keV (99.7% probability upper limit), and no photons were detected above ~10 keV. The burst is shorter at higher energies, which is similar to the behavior of long gamma-ray bursts (GRBs). We consider the possibility that the burst lies at very high redshift and that the low value of E is due to the cosmological redshift, and show that this is very unlikely. We find that the properties of XRF 020903 are consistent with the relation between the fluences S(7-30 keV) and S(30-400 keV), found by Barraud et al. for GRBs and X-ray-rich GRBs, and are consistent with the extension by a decade of the hardness-intensity correlation found by the same authors. Assuming that XRF 020903 lies at a redshift z = 0.25, as implied by the host galaxy of the candidate optical and radio afterglows of this burst, we find that the properties of XRF 020903 are consistent with an extension by a factor ~300 of the relation between the isotropic-equivalent energy Eiso and the peak Epeak of the νFν spectrum (in the source frame of the burst) found by Amati et al. for GRBs. The results presented in this paper therefore provide evidence that X-ray flashes (XRFs), X-ray-rich GRBs, and GRBs form a continuum and are a single phenomenon. The results also impose strong constraints on models of XRFs and X-ray-rich GRBs.
134 citations
01 Jan 2004
TL;DR: In this article, the authors show a new habit that, actually it's a very old habit to do that can make your life more qualified, when feeling bored of always chatting with your friends all free time, you can find the book enPDF gamma ray bursts 30 years of discovery and then read it.
Abstract: Change your habit to hang or waste the time to only chat with your friends. It is done by your everyday, don't you feel bored? Now, we will show you the new habit that, actually it's a very old habit to do that can make your life more qualified. When feeling bored of always chatting with your friends all free time, you can find the book enPDF gamma ray bursts 30 years of discovery and then read it.
122 citations
Massachusetts Institute of Technology1, Los Alamos National Laboratory2, Tokyo Institute of Technology3, University of Chicago4, University of California, Berkeley5, University of California, Santa Cruz6, National Space Development Agency of Japan7, Osaka University8, Aoyama Gakuin University9, Hoffmann-La Roche10, National Institute for Space Research11, Tata Institute of Fundamental Research12
TL;DR: An exceptionally intense gamma-ray burst, GRB 030329, was detected and localized by the instruments on board the High Energy Transient Explorer satellite (HETE) at 11:37:14 UT on 2003 March 29 as discussed by the authors.
Abstract: An exceptionally intense gamma-ray burst, GRB 030329, was detected and localized by the instruments on board the High Energy Transient Explorer satellite (HETE) at 11:37:14 UT on 2003 March 29. The burst consisted of two ~10 s pulses of roughly equal brightness and an X-ray tail lasting more than 100 s. The energy fluence in the 30-400 keV energy band was Sγ = 1.2 × 10-4 ergs cm-2, making GRB 030329 one of the brightest GRBs ever detected. Communication of a 2' error box 73 minutes after the burst allowed the rapid detection of a counterpart in the optical, X-ray, and radio and the ensuing discovery of a supernova with most unusual characteristics. Analyses of the burst light curves reveal the presence of a distinct, bright, soft X-ray component underlying the main GRB; the 2-10 keV fluence of this component is ~7 × 10-6 ergs cm-2. The main pulses of GRB 030329 were preceded by two soft, faint, nonthermal bumps. We present details of the HETE observations of GRB 030329.
65 citations
TL;DR: In this article, an exceptionally intense gamma-ray burst, GRB030329, was detected and localized by the instruments on board the High Energy Transient Explorer satellite (HETE) at 11:37:14 UT on 29 March 2003.
Abstract: An exceptionally intense gamma-ray burst, GRB030329, was detected and localized by the instruments on board the High Energy Transient Explorer satellite (HETE) at 11:37:14 UT on 29 March 2003. The burst consisted of two \~10s pulses of roughly equal brightness and an X-ray tail lasting >100s. The energy fluence in the 30-400 keV energy band was 1.08e-4 erg/cm2, making GRB030329 one of the brightest GRBs ever detected. Communication of a 2 arcmin error box 73 minutes after the burst allowed the rapid detection of a counterpart in the optical, X-ray, radio and the ensuing discovery of a supernova with most unusual characteristics. Analyses of the burst lightcurves reveal the presence of a distinct, bright, soft X-ray component underlying the main GRB: the 2-10 keV fluence of this component is ~7e-6 erg/cm2. The main pulses of GRB030329 were preceded by two soft, faint, non-thermal bumps. We present details of the HETE observations of GRB030329.
54 citations
University of Chicago1, Massachusetts Institute of Technology2, Centre national de la recherche scientifique3, National Institute for Space Research4, Goddard Space Flight Center5, Los Alamos National Laboratory6, Space Sciences Laboratory7, Tokyo Institute of Technology8, University of Tokyo9, University of California, Santa Cruz10
TL;DR: The High Energy Explorer Satellite 2 (HETE-2) mission has been highly productive as mentioned in this paper, and it has observed more than 250 γ-ray bursts (GRBs) so far.
28 citations
TL;DR: RAPTOR as discussed by the authors is a fully autonomous robotic system that is designed to identify and make follow-up observations of optical transients with durations as short as one minute, which can detect bright optical emission from GRB021211, a burst with modest gamma-ray fluence.
Abstract: Laboratory. RAPTOR is a fully autonomous robotic system that is designed to identify and make follow-up observations of optical transients with durations as short as one minute. The RAPTOR design is based on Biomimicry of Human Vision. The sky monitor is composed of two identical arrays of telescopes, separated by 38 kilometers, which stereoscopically monitor a field of about 1300 square-degrees for transients. Both monitoring arrays are carried on rapidly slewing mounts and are composed of an ensemble of wide-field telescopes clustered around a more powerful narrow-field telescope called the “fovea” telescope. All telescopes are coupled to real-time analysis pipelines that identify candidate transients and relay the information to a central decision unit that filters the candidates to find real celestial transients and command a response. When a celestial transient is found, the system can point the fovea telescopes to any position on the sky within five seconds and begin follow-up observations. RAPTOR also responds to Gamma Ray Burst (GRB) alerts generated by GRB monitoring spacecraft. Here we present RAPTOR observations of GRB 021211 that constitute the earliest detection of optical emission from that event and are the second fastest achieved for any GRB. The detection of bright optical emission from GRB021211, a burst with modest gamma-ray fluence, indicates that prompt optical emission, detectable with small robotic telescopes, is more common than previously thought. Further, the very fast decline of the optical afterglow from GRB 021211 suggests that some so-called “optically dark” GRBs were not detected only because of the slow response of the follow-up telescopes. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
22 citations
01 Oct 2004
TL;DR: The Burst Alert Telescope (BAT) on Swift has two main types of rate triggers: short and long as discussed by the authors, which can select energy ranges of 15 −25, 15 −50, 25 −100 and 50 −350 KeV.
Abstract: The Burst Alert Telescope (BAT) on Swift has two main types of “rate” triggers: short and long. Short trigger time scales range from 4ms to 64ms, while long triggers are 64ms to ≈ 16 seconds. While both short and long trigger have criteria with one background sample (traditional “one‐sided” triggers), the long triggers can also have criteria with two background samples (“bracketed” triggers) which remove trends in the background. Both long and short triggers can select energy ranges of 15–25, 15–50, 25–100 and 50–350 KeV. There are more than 180 short triggering criteria and approximately 500 long triggering criteria used to detect gamma ray bursts. To fully utilize these criteria, the thresholds must be set correctly. The optimum thresholds are determined by a tradeoff between avoiding false triggers and capturing as many bursts as possible. We use realistic simulated orbital variations, which are the prime cause of false triggers.
10 citations
Journal Article•
9 citations
TL;DR: In this paper, a tradeoff between avoiding false triggers and capturing as many bursts as possible is made for detecting gamma ray bursts using simulated orbital variations, which are the prime cause of false triggers.
Abstract: Swift has two main types of ``rate'' triggers: short and long. Short trigger time scales range from 4ms to 64ms, while long triggers are 64ms to ~ 16 seconds. While both short and long trigger have criteria with one background sample (traditional ``one-sided'' triggers), the long triggers can also have criteria with two background samples (``bracketed'' triggers) which remove trends in the background. Both long and short triggers can select energy ranges of 15-25, 15-50, 25-100 and 50-350 KeV. There are more than 180 short triggering criteria and approximately 500 long triggering criteria used to detect gamma ray bursts. To fully utilize these criteria, the thresholds must be set correctly. The optimum thresholds are determined by a tradeoff between avoiding false triggers and capturing as many bursts as possible. We use realistic simulated orbital variations, which are the prime cause of false triggers.
7 citations
TL;DR: The BAT instrument on the Swift satellite as mentioned in this paper tells the satellite where to point to make immediate follow-up observations of GRBs, and the science software on board must efficiently process gamma-ray events coming in at up to 34 kHz, identify rate increases that could be due to GRBs while disregarding those from known sources.
Abstract: The BAT instrument tells the Swift satellite where to point to make immediate follow-up observations of GRBs. The science software on board must efficiently process gamma-ray events coming in at up to 34 kHz, identify rate increases that could be due to GRBs while disregarding those from known sources, and produce images to accurately and rapidly locate new Gamma-ray sources.
03 Feb 2004
TL;DR: In addition to providing the initial gamma-ray burst trigger and location, the Swift Burst Alert Telescope (BAT) will also perform an all-sky hard x-ray survey based on serendipitous pointings resulting from the study of Gamma-ray bursts as discussed by the authors.
Abstract: In addition to providing the initial gamma-ray burst trigger and location, the Swift Burst Alert Telescope (BAT) will also perform an all-sky hard x-ray survey based on serendipitous pointings resulting from the study of gamma-ray bursts. BAT was designed with a very wide field-of-view (FOV) so that it can observe roughly 1/7 of the sky at any time. Since gamma-ray bursts are uniformly distributed over the sky, the final BAT survey coverage is expected to be nearly uniform. BAT's large effective area and long sky exposures will produce a 15 - 150 keV survey with up to 30 times better sensitivity than any previous hard x-ray survey (e.g. HEAO A4). Since the sensitivity of deep exposures in this energy range is systematics limited, the ultimate survey sensitivity depends on the relative sizes of the statistical and systematic errors in the data. Many careful calibration experiments were performed at NASA/Goddard Space Flight Center to better understand the BAT instrument's response to 15-150 keV gamma-rays incident from any direction within the FOV. Using radioactive sources of gamma-rays with known locations and energies, the Swift team can identify potential systematic errors in the telescope's performance and estimate the actual Swift hard x-ray survey sensitivity in flight. These calibration results will be discussed and a preliminary parameterization of the BAT instrument response will be presented. While the details of the individual BAT CZT detector response will be presented elsewhere in these proceedings, this talk will focus on the translation of the calibration experimental data into overall hard x-ray survey sensitivity.
University of Chicago1, Massachusetts Institute of Technology2, Centre national de la recherche scientifique3, National Institute for Space Research4, Goddard Space Flight Center5, Los Alamos National Laboratory6, Space Sciences Laboratory7, Tokyo Institute of Technology8, University of Tokyo9, University of California, Santa Cruz10
TL;DR: The HETE-2 mission has been highly productive as discussed by the authors, and has observed more than 250 GRB bursts with afterglows, and as of now, 11 of them have known redshifts, indicating that GRBs and their progenitors evolve strongly with redshift.
Abstract: The HETE-2 mission has been highly productive. It has observed more than 250 GRBs so far. It is currently localizing 25 - 30 GRBs per year, and has localized 43 GRBs to date. Twenty-one of these localizations have led to the detection of X-ray, optical, or radio afterglows, and as of now, 11 of the bursts with afterglows have known redshifts. HETE-2 has confirmed the connection between GRBs and Type Ic supernovae, a singular achievement and certainly one of the scientific highlights of the mission so far. It has provided evidence that the isotropic-equivalent energies and luminosities of GRBs are correlated with redshift, implying that GRBs and their progenitors evolve strongly with redshift. Both of these results have profound implications for the nature of GRB progenitors and for the use of GRBs as a probe of cosmology and the early universe. HETE-2 has placed severe constraints on any X-ray or optical afterglow of a short GRB. It is also solving the mystery of “optically dark” GRBs, and revealing the nature of X-ray flashes.
20 Jan 2004
TL;DR: In this paper, the properties of 32k CdZnTe detectors have been studied in the pre-flight calibration of the Burst Alert Telescope (BAT) on board the Swift Gamma-ray Burst Explorer (scheduled for launch in January 2004).
Abstract: The properties of 32k CdZnTe detectors have been studied in the
pre-flight calibration of Burst Alert Telescope (BAT) on-board the
Swift Gamma-ray Burst Explorer (scheduled for launch in January 2004).
After corrections of the linearity and the gain, the energy resolution
of summed spectrum is 7.0 keV (FWHM) at 122~keV. In order to construct
response matrices for the BAT instrument, we extracted
mobility-lifetime (μτ) products for electrons and holes in the
CdZnTe. Based on a new method applied to 57 Co spectra taken at different bias voltages, μτ for electrons ranges from
5.0x10 -4 to 1.0x10 -2 cm 2 V -1 , while μτ for holes ranges from 1.0x10 -5 to
1.7x10 -4 cm 2 V -1 . We show that the distortion of the spectrum and the peak efficiency of the BAT instrument are well reproduced by the μτ database constructed in the calibration.
28 Sep 2004
TL;DR: The Burst Alert Telescope (BAT) on the Swift gamma-ray burst mission will perform the first new all sky hard x-ray survey since 1977 as discussed by the authors, which is a coded aperture instrument with 17 arcminute pixels and a 2 ster partially coded field of view.
Abstract: The Burst Alert Telescope (BAT) on the Swift gamma-ray burst mission will perform the first new all sky hard x-ray survey since 1977. BAT is a coded aperture instrument with 17 arcminute pixels and a 2 ster partially coded field of view. The imaging area has 32768 CdZnTe detectors, each 4X4X2 mm, with a total area of 5243 cm2. Swift will perform pointings covering >64% of the sky each day and achieve an integrated sensitivity in three years of 0.6 milliCrabs for sources well off the Galactic plane. This survey is expected to identify hundreds of new highly obscured AGN.
Journal Article•
Japan Aerospace Exploration Agency1, Tokyo Institute of Technology2, Aoyama Gakuin University3, National Institutes of Natural Sciences, Japan4, Massachusetts Institute of Technology5, Centre national de la recherche scientifique6, Los Alamos National Laboratory7, University of Chicago8, University of California, Berkeley9, University of California, Santa Cruz10, Goddard Space Flight Center11, National Institute for Space Research12, Tata Institute of Fundamental Research13, INAF14, University of Miyazaki15
01 Oct 2004
TL;DR: In this paper, the fluence ratio of two X-ray flashes (XRFs), XRF010213 and XRF020903, was found to be 11.4 and 5.6 in the 2-30 keV to 30-400 keV energy band.
Abstract: We report HETE‐2 WXM and FREGATE observations of two X‐ray flashes (XRFs), XRF010213 and XRF020903. The signal is only seen in 10 seconds, and this feature is similar to that of the “long” GRBs. According to the time‐averaged spectral analysis using both WXM and FREGATE data, the fluence ratio of 2–30 keV to 30–400 keV energy band is 11.4 and 5.6 for XRF010213 and XRF020903 respectively. The Epeak energy in the Band function is < 10 keV. They are likely to belong to the same class as the X‐ray flash events detected with GINGA and BeppoSAX. In this paper, we will present the detail study of the prompt emission of XRF010213 and XRF020903, and compare with the characteristics of classic GRBs.
01 Oct 2004
TL;DR: The Burst Alert Telescope (BAT) on the Swift gamma-ray burst mission serves as the GRB trigger for the Swift as well as a sensitive imaging telescope for the energy range of 15-150 keV as mentioned in this paper.
Abstract: The Burst Alert Telescope (BAT) on the Swift gamma‐ray burst mission serves as the GRB trigger for Swift as well as a sensitive imaging telescope for the energy range of 15–150 keV. All BAT data products will be available to the astronomical community along with a complete set of analysis tools. Gamma‐ray burst data products include rapid discovery messages delivered immediately via the GRB Coordinates Network, and event‐by‐event data from which light curves and spectra of the burst are generated. During nominal operations, the instrument provides accumulated survey histograms with 5‐minute time sampling and appropriate energy resolution. These survey accumulations are analyzed in a pipeline to detect new sources and derive light curves of known sources. The 5‐minute surveys will also be combined to produce the BAT all sky hard X‐ray survey. In addition, the instrument accumulates high time resolution light curves of the brightest BAT sources in multiple energy bands, which are merged into a source light curve database on the ground. The BAT science data products and analysis tools will be described in this paper.
01 Jan 2004
TL;DR: The Burst Alert Telescope (BAT) as discussed by the authors provides the gamma-ray burst triggers and locations for the Swift Gamma-Ray Burst Explorer, and performs a 15 keV − 150 keV all-sky hard x-ray survey based on the serendipitous pointings resulting from the study of gamma-rays.
Abstract: The Burst Alert Telescope (BAT), a large coded aperture instrument with a wide field‐of‐view (FOV), provides the gamma‐ray burst triggers and locations for the Swift Gamma‐Ray Burst Explorer. In addition to providing this imaging information, BAT will perform a 15 keV – 150 keV all‐sky hard x‐ray survey based on the serendipitous pointings resulting from the study of gamma‐ray bursts, and will also monitor the sky for transient hard x‐ray sources. For BAT to provide spectral and photometric information for the gamma‐ray bursts, the transient sources and the all‐sky survey, the BAT instrument response must be determined to an increasingly greater accuracy. This paper describes the spectral models and the ground calibration experiments used to determine the BAT response to an accuracy suitable for gamma‐ray burst studies.
Posted Content•
TL;DR: The Swift satellite as mentioned in this paper is a self-contained observatory that will bring new capabilities to the observing of the early afterglow emission of Gamma-ray Bursts, which is completely autonomous and will do all of the observations without help from the ground.
Abstract: The Swift satellite will be a self-contained observatory that will bring new capabilities to the observing of the early afterglow emission of Gamma-ray Bursts. Swift is completely autonomous and will do all of the observations without help from the ground. There are three instruments on Swift. A large (5200 sq cm) coded aperture imager will locate the bursts within about 15 seconds. The satellite will be able to slew to point at the location within a minute or two. There are two narrow field of view instruments: an optical telescope and an x-ray telescope. Thus, Swift will provide simultaneous gamma-ray, x-ray, and optical observations of Gamma-ray bursts soon after the burst. A key to the success of Swift will be its ability to detect and locate a large number of gamma-ray bursts quick enough that the narrow field of view instruments can follow up. The results of simulations show that Swift will be able to detect about 300 bursts a year and locate about 150. The number that Swift will be able to slew to depends on constraints built into the satellite bus. Preliminary results indicate that we might be able to slew to 100 bursts per year, but that is heavily dependent on satellite operations.
Journal Article•