25 results on '"Onda K"'
Search Results
2. Spectral Cross-calibration of the Konus-Wind, the Suzaku/WAM, and the Swift/BAT Data using Gamma-Ray Bursts
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Sakamoto, T., Pal'shin, V., Yamaoka, K., Ohno, M., Sato, G., Aptekar, R., Barthelmy, S., Baumgartner, W., Cummings, J., Fenimore, E., Frederiks, D., Gehrels, N., Golenetskii, S., Krimm, H., Markwardt, C., Onda, K., Palmer, D., Parsons, A., Stamatikos, M., Sugita, S., Tashiro, M., Tueller, J., and Ukwatta, T.
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Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report on the spectral cross-calibration results of the Konus-Wind, the Suzaku/WAM, and the Swift/BAT instruments using simultaneously observed gamma-ray bursts (GRBs). This is the first attempt to use simultaneously observed GRBs as a spectral calibration source to understand systematic problems among the instruments. Based on these joint spectral fits, we find that 1) although a constant factor (a normalization factor) agrees within 20% among the instruments, the BAT constant factor shows a systematically smaller value by 10-20% compared to that of Konus-Wind, 2) there is a systematic trend that the low-energy photon index becomes steeper by 0.1-0.2 and Epeak becomes systematically higher by 10-20% when including the BAT data in the joint fits, and 3) the high-energy photon index agrees within 0.2 among the instruments. Our results show that cross-calibration based on joint spectral analysis is an important step to understanding the instrumental effects which could be affecting the scientific results from the GRB prompt emission data., Comment: 82 pages, 88 figures, accepted for publication in PASJ
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- 2010
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3. Testing the Epeak - Eiso relation for GRBs detected by Swift and Suzaku-WAM
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Krimm, H. A., Yamaoka, K., Sugita, S., Ohno, M., Sakamoto, T., Barthelmy, S. D., Gehrels, N., Hara, R., Norris, J. P., Ohmori, N., Onda, K., Sato, G., Tanaka, H., Tashiro, M., and Yamauchi, M.
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Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
One of the most prominent, yet controversial associations derived from the ensemble of prompt-phase observations of gamma-ray bursts (GRBs) is the apparent correlation in the source frame between the peak energy Epeak) of the nu-F(nu) spectrum and the isotropic radiated energy, Eiso. Since most gamma-ray bursts (GRBs) have Epeak above the energy range (15-150 keV) of the Burst Alert Telescope (BAT) on Swift, determining accurate Epeak values for large numbers of Swift bursts has been difficult. However, by combining data from Swift/BAT and the Suzaku Wide-band All-Sky Monitor (WAM), which covers the energy range from 50-5000 keV, for bursts which are simultaneously detected, one can accurately fit Epeak and Eiso and test the relationship between them for the Swift sample. Between the launch of Suzaku in July 2005 and the end of April 2009, there were 48 gamma-ray bursts (GRBs) which triggered both Swift/BAT and WAM and an additional 48 bursts which triggered Swift and were detected by WAM, but did not trigger. A BAT-WAM team has cross-calibrated the two instruments using GRBs, and we are now able to perform joint fits on these bursts to determine their spectral parameters. For those bursts with spectroscopic redshifts, we can also calculate the isotropic energy. Here we present the results of joint Swift/BAT-Suzaku/WAM spectral fits for 91 of the bursts detected by the two instruments. We show that the distribution of spectral fit parameters is consistent with distributions from earlier missions and confirm that Swift bursts are consistent with earlier reported relationships between Epeak and isotropic energy. We show through time-resolved spectroscopy that individual burst pulses are also consistent with this relationship., Comment: Accepted for publication in the Astrophysical Journal
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- 2009
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4. Status of GRB Observations with the Suzaku Wideband All-sky Monitor
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Tashiro, M. S., Terada, Y., Urata, Y., Onda, K., Kodaka, N., Endo, A., Suzuki, M., Morigami, K., Yamaoka, K., Nakagawa, Y. E., Sugita, S., Fukazawa, Y., Ohno, M., Takahashi, T., Kira, C., Uehara, T., Tamagawa, T., Enoto, T., Miyawaki, R., Nakazawa, K., Makishima, K., Sonoda, E., Yamauchi, M., Maeno, S., Tanaka, H., Hara, R., Kokubun, M., Hong, S. J., Murakami, T., Tajima, H., and team, the HXD
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Astrophysics - Abstract
The Wide-band All-sky Monitor (WAM) is a function of the large lateral BGO shield of the Hard X-ray Detector (HXD) onboard Suzaku. Its large geometrical area of 800 cm^2 per side, the large stopping power for the hard X-rays and the wide-field of view make the WAM an ideal detector for gamma-ray bursts (GRBs) observations in the energy range of 50-5000 keV. In fact, the WAM has observed 288 GRBs confirmed by other satellites, till the end of May 2007., Comment: 4 pages, 4 figures, to be published in the proceedings of ''Gamma Ray Bursts 2007'', Santa Fe, New Mexico, November 5-9
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- 2008
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5. Swift captures the spectrally evolving prompt emission of GRB 070616
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Starling, R. L. C., O'Brien, P. T., Willingale, R., Page, K. L., Osborne, J. P., De Pasquale, M., Nakagawa, Y. E., Kuin, N. P. M., Onda, K., Norris, J. P., Ukwatta, T. N., Kodaka, N., Burrows, D. N., Kennea, J. A., Page, M. J., Perri, M., and Markwardt, C. B.
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Astrophysics - Abstract
The origins of Gamma-ray Burst prompt emission are currently not well understood and in this context long, well-observed events are particularly important to study. We present the case of GRB 070616, analysing the exceptionally long-duration multipeaked prompt emission, and later afterglow, captured by all the instruments on-board Swift and by Suzaku WAM. The high energy light curve remained generally flat for several hundred seconds before going into a steep decline. Spectral evolution from hard to soft is clearly taking place throughout the prompt emission, beginning at 285 s after the trigger and extending to 1200 s. We track the movement of the spectral peak energy, whilst observing a softening of the low energy spectral slope. The steep decline in flux may be caused by a combination of this strong spectral evolution and the curvature effect. We investigate origins for the spectral evolution, ruling out a superposition of two power laws and considering instead an additional component dominant during the late prompt emission. We also discuss origins for the early optical emission and the physics of the afterglow. The case of GRB 070616 clearly demonstrates that both broadband coverage and good time resolution are crucial to pin down the origins of the complex prompt emission in GRBs., Comment: 13 pages, 11 figures (2 in colour), MNRAS accepted
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- 2007
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6. Very early multi-color observations of the plateau phase of GRB 041006 afterglow
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Urata, Y., Huang, K. Y., Qiu, Y. L., Hu, J., Kuo, P. H., Tamagawa, T., Ip, W. H., Kinoshita, D., Fukushi, H., Isogai, M., Miyata, T., Nakada, Y., Aoki, T., Soyano, T., Tarusawa, K., Mito, H., Onda, K., Ibrahimov, M., Pozanenko, A., and Makishima, K.
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Astrophysics - Abstract
Observations of the optical afterglow of GRB 041006 with the Kiso Observatory 1.05 m Schmidt telescope, the Lulin Observatory 1.0 m telescope and the Xinglong Observatory 0.6 m telescope. Three-bands (B, V and R) of photometric data points were obtained on 2004 October 6, 0.025-0.329 days after the burst. These very early multi band light curves imply the existence of a color dependent plateau phase. The B-band light curve shows a clear plateau at around 0.03 days after the burst. The R band light curve shows the hint of a plateau, or a possible slope change, at around 0.1 days after the burst. The overall behavior of these multi-band light curves may be interpreted in terms of the sum of two separate components, one showing a monotonic decay the other exhibiting a rising and a falling phase, as described by the standard afterglow model., Comment: 11 pages, 2 figures, Accepted to ApJ Letters
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- 2006
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7. Extensive multiband study of the X-ray rich GRB 050408. A likely off-axis event with an intense energy injection
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Postigo, A de Ugarte, Fatkhullin, T. A., Johannesson, G., Gorosabel, J., Sokolov, V. V., Castro-Tirado, A. J., Balega, Yu. Yu., Spiridonova, O. I., Jelinek, M., Guziy, S., Perez-Ramirez, D., Hjorth, J., Laursen, P., Bersier, D., Pandey, S. B., Bremer, M., Monfardini, A., Huang, K. Y., Urata, Y., Ip, W. H., Tamagawa, T., Kinoshita, D., Mizuno, T., Arai, Y., Yamagishi, H., Soyano, T., Usui, F., Tashiro, M., Abe, K., Onda, K., Aslan, Z., Khamitov, I., Ozisik, T., Kiziloglu, U., Bikmaev, I., Sakhibullin, N., Burenin, R., Pavlinsky, M., Sunyaev, R., Bhattacharya, D., Kamble, A. P., Chandra, C. H. Ishwara, and Trushkin, S. A.
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Astrophysics - Abstract
Aims. Understand the shape and implications of the multiband light curve of GRB 050408, an X-ray rich (XRR) burst. Methods. We present a multiband optical light curve, covering the time from the onset of the gamma-ray event to several months after, when we only detect the host galaxy. Together with X-ray, millimetre and radio observations we compile what, to our knowledge, is the most complete multiband coverage of an XRR burst afterglow to date. Results. The optical and X-ray light curve is characterised by an early flattening and an intense bump peaking around 6 days after the burst onset. We explain the former by an off-axis viewed jet, in agreement with the predictions made for XRR by some models, and the latter with an energy injection equivalent in intensity to the initial shock. The analysis of the spectral flux distribution reveals an extinction compatible with a low chemical enrichment surrounding the burst. Together with the detection of an underlying starburst host galaxy we can strengthen the link between XRR and classical long-duration bursts., Comment: 9 pages, 4 figures, Accepted for publication in A&A Letters
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- 2006
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8. Multi-color Shallow Decay and Chromatic Breaks in the GRB 050319 Optical Afterglow
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Huang, K. Y., Urata, Y., Kuo, P. H., Ip, W. H., Ioka, K., Aoki, T., Chen, C. W., Chen, W. P., Isogai, M., Lin, H. C., Makishima, K., Mito, H., Miyata, T., Nakada, Y., Nishiura, S., Onda, K., Qiu, Y., Soyano, T., Tamagawa, T., Tarusawa, K., Tashiro, M., and Yoshioka, T.
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Astrophysics - Abstract
Multi-wavelength B, V, R, I observations of the optical afterglow of GRB 050319 were performed by the 1.05-m telescope at Kiso Observatory and the 1.0-m telescope at Lulin Observatory from 1.31 hours to 9.92 hours after the burst. Our R band lightcurves, combined with other published data, can be described by the smooth broken power-law function, with $\alpha_1$ = -0.84 $\pm$0.02 to $\alpha_2$ = -0.48$\pm$0.03, 0.04 days after the GRB. The optical lightcurves are characterized by shallow decays-- as was also observed in the X-rays-- which may have a similar origin, related to energy injection. However, our observations indicate that there is still a puzzle concerning the chromatic breaks in the R band lightcurve (at 0.04 days) and the X-ray lightcurve (at 0.004 days) that remains to be solved., Comment: 14 pages, 2 figures, accpeted for publication in ApJL
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- 2006
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9. In-Orbit Performance of the Hard X-ray Detector on board Suzaku
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Kokubun, M., Makishima, K., Takahashi, T., Murakami, T., Tashiro, M., Fukazawa, Y., Kamae, T., Madejski, G. M., Nakazawa, K., Yamaoka, K., Terada, Y., Yonetoku, D., Watanabe, S., Tamagawa, T., Mizuno, T., Kubota, A., Isobe, N., Takahashi, I., Sato, G., Takahashi, H., Hong, S., Kawaharada, M., Kawano, N., Mitani, T., Murashima, M., Suzuki, M., Abe, K., Miyawaki, R., Ohno, M., Tanaka, T., Yanagida, T., Itoh, T., Ohnuki, K., Tamura, K., Endo, Y., Hirakuri, S., Hiruta, T., Kitaguchi, T., Kishishita, T., Sugita, S., Takeda, S., Enoto, T., Hirasawa, A., Katsuta, J., Matsumura, S., Onda, K., Sato, M., Ushio, M., Ishikawa, S., Murase, K., Odaka, H., Yaji, Y., Yamada, S., Yamasaki, T., and Yuasa, T.
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Astrophysics - Abstract
The in-orbit performance and calibration of the Hard X-ray Detector (HXD) on board the X-ray astronomy satellite Suzaku are described. Its basic performances, including a wide energy bandpass of 10-600 keV, energy resolutions of ~4 keV (FWHM) at 40 keV and ~11% at 511 keV, and a high background rejection efficiency, have been confirmed by extensive in-orbit calibrations. The long-term gains of PIN-Si diodes have been stable within 1% for half a year, and those of scintillators have decreased by 5-20%. The residual non-X-ray background of the HXD is the lowest among past non-imaging hard X-ray instruments in energy ranges of 15-70 and 150-500 keV. We provide accurate calibrations of energy responses, angular responses, timing accuracy of the HXD, and relative normalizations to the X-ray CCD cameras using multiple observations of the Crab Nebula., Comment: 45 pages, 40 figures and 9 tables; accepted for Pulications of the Astronomical Society of Japan
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- 2006
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10. Swift and Suzaku Observations of the X-Ray Afterglow from the GRB 060105
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Tashiro, M. S., Abe, K., Angelini, L., Barthelmy, S., Gehrels, N., Ishikawa, N., Kaluzienski, L. J., Kawai, N., Kelley, R. L., Kinugasa, K., Kodaira, H., Kohmura, T., Kubota, K., Maeda, Y., Maeno, S., Murakami, H., Murakami, T., Nakagawa, Y. E., Nakazawa, K., Nousek, J., Okuno, S., Onda, K., Reeves, J. N., Ricker, G., Sato, G., Sonoda, E., Suzuki, M., Takahashi, T., Tamagawa, T., Torii, K., Ueda, Y., Urata, Y., Yamaoka, K., Yamauchi, M., Yonetoku, D., Yoshida, A., and Yoshinari, S.
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Astrophysics - Abstract
Results are presented of early X-ray afterglow observations of GRB 060105 by Swift and Suzaku. The bright, long gamma-ray burst GRB 060105 triggered the Swift Burst Alert Telescope (BAT) at 06:49:28 on 5 January 2006. The Suzaku team commenced a pre-planned target of opportunity observation at 19 ks (5.3 hr) after the Swift trigger. Following the prompt emission and successive very steep decay, a shallow decay was observed from T_0+187 s to T_0+1287 s. After an observation gap during T_0 +(1.5-3) ks, an extremely early steep decay was observed in T_0+(4-30) ks. The lightcurve flattened again at T_0+30 ks, and another steep decay followed from T_0+50 ks to the end of observations. Both steep decays exhibited decay indices of 2.3 - 2.4. This very early break, if it is a jet break, is the earliest case among X-ray afterglow observations, suggesting a very narrow jet whose opening angle is well below 1 degree. The unique Suzaku/XIS data allow us to set very tight upper limits on line emission or absorption in this GRB. For the reported pseudo-redshift of z=4.0+/-1.3 the upper limit on the iron line equivalent width is 50 eV., Comment: 8 pages, 5 figures, Accepted for publication in PASJ Suzaku Special Issue (vol. 58)
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- 2006
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11. When Do Internal Shocks End and External Shocks Begin? Early-Time Broadband Modelling of GRB 051111
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Butler, N. R., Li, W., Perley, D., Huang, K. Y., Urata, Y., Prochaska, J. X., Bloom, J. S., Filippenko, A. V., Foley, R. J., Kocevski, D., Chen, H. -W., Qiu, Y., Kuo, P. H., Huang, F. Y., Ip, W. H., Tamagawa, T., Onda, K., Tashiro, M., Makishima, K., Nishihara, S., and Sarugaku, Y.
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Astrophysics - Abstract
Even with the renaissance in gamma-ray burst (GRB) research fostered by the Swift satellite, few bursts have both contemporaneous observations at long wavelengths and exquisite observations at later times across the electromagnetic spectrum. We present here contemporaneous imaging with the KAIT robotic optical telescope, dense optical sampling with Lulin, and supplemented with infrared data from PAIRITEL and radio to gamma-ray data from the literature. For the first time, we can test the constancy of microphysical parameters in the internal-external shock paradigm and carefully trace the flow of energy from the GRB to the surrounding medium. KAIT data taken <~1 minute after the start of GRB051111 and coinciding with the fading gamma-ray tail of the prompt emission indicate a smooth re-injection of energy into the shock. No color change is apparent in observations beginning ~1.5 minutes after the GRB and lasting for the first hour after the burst. There are achromatic flux modulations about the best-fit model at late (t~10^4 s) times, possibly due to variations in the external density. We find that the host-galaxy extinction is well fit by a curve similar to that ofthe Small Magellanic Cloud. Low visual extinction, A_V~0.2 mag, combined with high column densities determined from the X-ray and optical spectroscopy (N_H> 10^21 cm^-2), indicate a low dust-to-metals ratio and a possible over-abundance of the light metals. An apparent small ratio of total to selective extinction (R_V~2) argues against dust destruction by the GRB. Time constancy of both the IR/optical/UV spectral energy distribution and the soft X-ray absorption suggests that the absorbing material is not local to the GRB., Comment: 21 pages, 6 figures, to Appear in ApJ v653, December, 10 2006
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- 2006
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12. GRBs Optical follow-up observation at Lulin observatory, Taiwan
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Huang, K. Y., Urata, Y., Ip, W. H., Tamagawa, T., Onda, K., and Makishima, K.
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Astrophysics - Abstract
The Lulin GRB program, using the Lulin One-meter Telescope (LOT) in Taiwan started in July 2003. Its scientific aims are to discover optical counterparts of XRFs and short and long GRBs, then to quickly observe them in multiple bands. Thirteen follow-up observations were provided by LOT between July 2003 and Feb. 2005. One host galaxy was found at GRB 031203. Two optical afterglows were detected for GRB 040924 and GRB 041006. In addition, the optical observations of GRB 031203 and a discussion of the non-detection of the optical afterglow of GRB 031203 are also reported in this article., Comment: 5 pages, 2 figure. Accepted for publication into "il nuovo cimento". Proceeding of the 4th Rome GRB conference, eds. L. Piro, L. Amati, S. Covino, B. Gendre
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- 2005
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13. GRB follow-up observations in the East-Asian region
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Urata, Y., Huang, K. Y., Ip, W. H., Qiu, Y., Hu, J. Y., Zhou, Xn., Tamagawa, T., Onda, K., and Makishima, K.
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Astrophysics - Abstract
In 2004, we established a Japan-Taiwan-China collaboration for GRB study in the East-Asian region. This serves as a valuable addition to the world-wide optical and infrared follow-up network, because the East-Asia region would otherwise be blank. We have been carrying out imaging and spectroscopic follow-up observations at Lulin (Taiwan), Kiso (Japan), WIDGET (Japan) and Xinglong (China). From Xinglong and Kiso, we can locate candidates and obtain early time spectra for afterglows. While WIDGET provides early time observations before the burst, the high-time resolution for multi-band light curves can be obtained at Lulin. With the data from these sites, we can obtain detailed information about the light curve and redshift of GRBs, which are important to understand the mechanism of the afterglows. Up to March 2005, ten follow-up observations have been provided by this East-Asia cooperation. Two optical afterglows were detected, GRB 040924 and GRB 041006. The results of the two detected afterglows are reported in this article., Comment: 4 pages, 1 figure. Accepted for publication into "il nuovo cimento". Proceeding of the 4th Rome GRB conference, eds. L. Piro, L. Amati, S. Covino, B. Gendre
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- 2005
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14. Optical Afterglow Observations of the Unusual Short-Duration Gamma-Ray Burst 040924
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Huang, K. Y., Urata, Y., Filippenko, A. V., Hu, J. H., Ip, W. H., Kuo, P. H., Li, W., Lin, H. C., Lin, Z. Y., Makishima, K., Onda, K., Qiu, Y., and Tamagawa, T.
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Astrophysics - Abstract
The 1-m telescope at Lulin Observatory and the 0.76-m Katzman Automatic Imaging Telescope at Lick Observatory were used to observe the optical afterglow of the short-duration (1.2--1.5 s) gamma-ray burst (GRB) 040924. This object has a soft high-energy spectrum, thus making it an exceptional case, perhaps actually belonging to the short-duration tail of the long-duration GRBs. Our data, combined with other reported measurements, show that the early R-band light curve can be described by two power laws with index alpha = -0.7 (at t = 16-50 min) and alpha = -1.06 (at later times). The rather small difference in the spectral indices can be more easily explained by an afterglow model invoking a cooling break rather than a jet break., Comment: 13 pages, 3 figures, accepted for publication in ApJL
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- 2005
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15. The search for optical emission on and before the GRB trigger with the WIDGET telescope
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Tamagawa, T., Usui, F., Urata, Y., Abe, K., Onda, K., Tashiro, M., Terada, Y., Fujiwara, H., Miura, N., Hirose, S., Kawai, N., Yoshida, A., Mori, M., and Makishima, K.
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Astrophysics - Abstract
WIDGET is a robotic telescope for monitoring the HETE-2 field-of-view to detect Gamma-ray Burst optical flashes or possible optical precursors. The system has 62degx62deg wide field-of-view which covers about 80% of HETE-2 one with a 2kx2k Apogee U10 CCD camera and a Canon EF 24mm f/1.4 wide-angle lens without a bandpass filter. WIDGET has been in operation since June 2004 at Akeno observing site where is about 200 km apart from Tokyo. Typical limiting magnitude with S/N=3 at the site is V=10mag for 5 seconds exposure and V=11mag for 30 seconds exposure. We had already six coincident observations with HETE-2 position alerts. It was, however, cloudy for all cases due to rainy season in Japan. Expected number of coincident observations under clear sky is about 5 events per year. We will extend the system in early 2005 for Swift era to monitor optical transients in wider field-of-view, multi-color or polarization modes., Comment: 4 pages, 4 figure. Accepted for publication into "il nuovo cimento". Proceeding of the 4th Rome GRB conference, eds. L. Piro, L. Amati, S. Covino, B. Gendre
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- 2005
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16. Testing the E(sub peak)-E(sub iso) Relation for GRBs Detected by Swift and Suzaku-WAM
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Krimm, H. A, Yamaoka, K, Sugita, S, Ohno, M, Sakamoto, T, Barthelmy, S. D, Gehrels, N, Hara, R, Onda, K, Sato, G, Tanaka, H, Tashiro, M, Yamauchi, M, Norris, J. P, and Ohmori, N
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Astronomy - Abstract
One of the most prominent, yet controversial associations derived from the ensemble of prompt-phase observations of gamma-ray bursts (GRBs) is the apparent correlation in the source frame between the peak energy (E(sub peak)) of the nuF(nu) spectrum and the isotropic radiated energy, E(sub iso). Since most gamma-ray bursts (GRBs) have E(sub peak) above the energy range (15-150 keV) of the Burst Alert Telescope (BAT) on Swift, determining accurate E(sub peak) values for large numbers of Swift bursts has been difficult. However, by combining data from Swift/BAT and the Suzaku Wide-band All-Sky Monitor (WAM), which covers the energy range from 50-5000 keV, for bursts which are simultaneously detected ; one can accurately fit E(sub peak) and E(sub iso) and test the relationship between them for the Swift sample. Between the launch of Suzaku in July 2005 and the end of March 2009, there were 45 gamma-ray bursts (GRBs) which triggered both Swift/BAT and WAM and an additional 47 bursts which triggered Swift and were detected by WAM, but did not trigger. A BAT-WAM team has cross-calibrated the two instruments using GRBs, and we are now able to perform joint fits on these bursts to determine spectral parameters. For those bursts with spectroscopic redshifts.. we can also calculate the isotropic energy. Here we present the results of joint Swift/BAT-Suzaku/WAM spectral fits for 86 of the bursts detected by the two instruments. We show that the distribution of spectral fit parameters is consistent with distributions from earlier missions and confirm that Swift, bursts are consistent with earlier reported relationships between Epeak and isotropic energy. We show through time-resolved spectroscopy that individual burst pulses are also consistent with this relationship.
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- 2009
17. Correlative Analysis of GRBs Detected by Swift and Suzaku- WAM
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Krimm, H.A, Sakamoto, T, Yamaoka, K, Sugita, S, Ohno, M, Sato, G, Hara, R, Ohmori, N, Tanaka, H, Yamauchi, M, Onda, K, and Tashiro, M
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Astronomy - Abstract
It is now well known that a complete understanding of the energetics of the prompt phase of gamma-ray bursts (GRBs) requires full knowledge of the spectrum, extending at least as high as the peak energy (Epeak) of the vF(v) spectrum. Since most gamma-ray bursts (GRBs) have Epeak above the energy range (15-150 keV) of the Burst Alert Telescope (BAT) on Swift, a full understanding of the prompt emission from Swift GRBs requires spectral fits over as broad an energy range as possible. This can be completed for bursts which are simultaneously detected by Swift BAT and the Suzaku Wide-band All-Sky Monitor (WAM), which covers the energy range from 50-5000 keV. Between the launch of Suzaku in July 2005 and the end of 2008, there were 44 gamma-ray bursts (GRBs) which triggered both Swift and WAM and an additional 41 bursts which triggered Swift and were detected by WAM, but did not trigger. A joint BAT-WAM team has cross-calibrated the two instruments using GRBs, and we are now able to perform joint fits on these bursts to determine spectral parameters including Epeak. The results of broad spectral fits allows us to understand the distribution of Epeak for Swift bursts and to calibrate Epeak estimators when Epeak is within the BAT energy range. For those bursts with spectroscopic redshifts, we can calculate the isotropic energy and study various correlations between Epeak and other global burst parameters. Here we present the results of joint Swift/BAT-Suzaku/WAM spectral fits for 77 of the bursts jointly detected by the two instruments. We show that the distribution of spectral fit parameters is consistent with distributions from earlier missions and confirm that Swift bursts are consistent with earlier reported relationships between Epeak and isotropic energy. We show through time-resolved spectroscopy that individual burst pulses are also consistent with this relationship.
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- 2009
18. Inclusion of exact exchange in the noniterative partial-differential-equation method of electron-molecule scattering - Application to e-N2
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Weatherford, C. A, Onda, K, and Temkin, A
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Atomic And Molecular Physics - Abstract
The noniterative partial-differential-equation (PDE) approach to electron-molecule scattering of Onda and Temkin (1983) is modified to account for the effects of exchange explicitly. The exchange equation is reduced to a set of inhomogeneous equations containing no integral terms and solved noniteratively in a difference form; a method for propagating the solution to large values of r is described; the changes in the polarization potential of the original PDE method required by the inclusion of exact static exchange are indicated; and the results of computations for e-N2 scattering in the fixed-nuclei approximation are presented in tables and graphs and compared with previous calculations and experimental data. Better agreement is obtained using the modified PDE method.
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- 1985
19. Calculation of the polarization potential for e-N2 collisions
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Onda, K and Temkin, A
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Nuclear And High-Energy Physics - Abstract
A polarization potential V(pol) for e-N2 collisions is calculated by the generalization of the static part of the method of polarized orbitals to molecular targets. Partial differential equations (PDE) are derived for polarized orbitals, which are functions of the distance (r) from the molecular center and angle (theta) from the molecular axis. The equations are solved with the use of the noniterative PDE technique. From the polarized orbitals a polarization potential can be constructed whose r and theta dependence is found to be significantly different from the well-known phenomenological one. The two potentials are further compared by carrying out limited hybrid-theory scattering calculations. Only those scattering results based on the calculated V(pol) are in satisfactory accord with experiment.
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- 1983
20. Electron scattering by CO2 - Elastic scattering, rotational excitation, and excitation of the asymmetric stretch at 10 eV impact energy
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Thirumalai, D, Truhlar, D. G, and Onda, K
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Atomic And Molecular Physics - Published
- 1981
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21. Elastic scattering and rotational excitation of a polyatomic molecule by electron impact - Acetylene
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Thirumalai, D, Truhlar, D. G, and Onda, K
- Subjects
Atomic And Molecular Physics - Abstract
Differential, integral, momentum transfer, and partial cross sections have been calculated for elastic scattering and rotational excitation of C2H2 by 10-eV electrons. The effective potential includes static, exchange, and polarization interactions calculated by the INDOX/1s method and the semiclassical exchange approximation with adiabatic polarization at large electron-molecule distances. The scattering is treated by well converged rotational close coupling using the centrifugal dominant scheme to select the channels included and including up to 32 coupled channels for a given total angular momentum. The calculated integral cross sections for pure elastic scattering and rotation excitation are 54.5 and 41.4 a(0)squared, respectively. These are much larger than the values (34.4 and 18.6 a(0)squared) previously (Onda and Truhlar, 1979) calculated for the isoelectronic molecule N2, at this energy. This illustrates how the greater spatial extent of C2H2 greatly increases the cross sections for pure elastic and rotationally inelastic scattering.
- Published
- 1981
22. Quantum mechanical study of elastic scattering and rotational excitation of CO by electrons
- Author
-
Onda, K and Truhlar, D. G
- Subjects
Atomic And Molecular Physics - Abstract
Coupling calculations of differential, integral, and momentum transfer cross sections for pure elastic scattering and rotational excitation of CO by electron impact are reported. The calculations are based on a static charge distribution that has correct dipole and quadrupole moments, has cusps at the nuclei, and is augmented by an SCF treatment of charge polarization and a local approximation for exchange. The rotationally summed cross sections, with no adjustable parameters in the scattering calculation, are in reasonably good agreement with the experimental cross sections but are somewhat larger at small scattering angles.
- Published
- 1980
- Full Text
- View/download PDF
23. SCF treatment of charge polarization effects in intermediate-energy electron scattering calculations with applications to N2
- Author
-
Onda, K and Truhlar, D. G
- Subjects
Atomic And Molecular Physics - Abstract
Converged rotational close coupling calculations of differential, integral, and momentum-transfer cross sections are obtained for seven model potentials for electron-N2 scattering at an impact energy of 30 eV. The model potentials involve a static potential calculated by the INDO/1s or INDOXI/1s method, and exchange potential calculated by the semiclassical exchange approximation from the INDO/1s or INDOXI/1s unperturbed electron density and a polarization potential. The polarization potentials used include the Buckley-Burke semiempirical one and various modifications of the INDOXI and INDO SCF (self-consistent-field) adiabatic polarization potentials. Without adjustment of parameters, good agreement is obtained with the angle dependence of the experimentally measured sum of the elastic and rotational excitation differential cross sections; however, the absolute value of the calculated cross sections is about 20-30% larger than the measured values in the best case, perhaps indicating that the model potentials are too strong or should have a nonzero imaginary part.
- Published
- 1979
- Full Text
- View/download PDF
24. Close-coupling calculations with an INDOX/1s static potential, semiclassical exchange, and a semi-empirical polarisation potential for electron-CO2 elastic scattering and rotational excitation
- Author
-
Onda, K and Truhlar, D. G
- Subjects
Atomic And Molecular Physics - Abstract
A semiempirical molecular-orbital method for modelling the effective potential for electron-molecule scattering is applied to elastic scattering and rotational excitation of CO2 at 20 eV impact energy. Agreement with experiment is reasonably good. The calculated rotationally summed integral cross section is 67.8 a sub 0 squared.
- Published
- 1979
25. Model potentials for electron scattering - Converged close coupling calculations for the differential cross section for e/-/N2 at 30-50 eV
- Author
-
Onda, K and Truhlar, D. G
- Subjects
Nuclear And High-Energy Physics - Abstract
A calculation has been made of the elastic scattering and rotational excitation cross sections for e(-)-N2 scattering at 30 and 50 eV using quantum chemical techniques specially designed to be applicable to elastic and inelastic electron scattering by general polyatomic molecules. The angle dependence of the sum of the elastic and rotational excitation differential cross sections is in good agreement with experiment at all scattering angles at both energies, but at 50 eV the difference from experiment exceeds the experimental uncertainty at small scattering angles and near the minimum of the differential cross section. At large scattering angles the rotational excitation cross sections are predicted to exceed the elastic scattering cross sections. The absolute cross sections agree with experiment at some angles but at other angles are as much as 51% (30 eV) or 90% (50 eV) higher; this may be due at least in part to the difficulty of putting the experimental results on an absolute scale.
- Published
- 1978
- Full Text
- View/download PDF
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