Spectral Evolution of weak bursts from SGR 1806-20 observed with INTEGRAL

We report on bursts from the Soft Gamma-Ray Repeater SGR 1806--20 detected with INTEGRAL in October 2003, during a period of moderate activity of the source. The spectral and temporal properties of 21 short bursts are consistent with those found in previous observations, even if these bursts are among the faintest observed in the 15-200 keV range from this source. During some of the bursts a clear spectral evolution is visible. The data also show, for the first time, evidence for a hardness-intensity anti-correlation within SGR 1806--20 bursts.Comment: Accepted for publication in Astronomy & Astrophysics Letter

Composition of Eucalyptus camaldulensis volatiles using direct thermal desorption coupled with comprehensive two-dimensional gas chromatography-time- of-flight-mass spectrometry

The direct qualification and quantitation of the volatile organic components of four Eucalyptus camaldulensis fruit samples, obtained from different geographical areas in Turkey, is studied using a direct thermal desorption (DTD) technique coupled with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry. It is found that the E. camaldulensis sample from Adrasan gave a slightly higher oil yield (1.18%) than the others. The number of components quantitatively identified from Adrasan, Belek, Kuyucak, and Cesme were 46, 54, 55, and 59, respectively. The main compounds found in the volatile oils were: aromadendrene (6.45-15.02%), eucalyptol (0.17-12.61%), ??-gurjunene (8.40-10.08%), terpinolen (1.98-8.39%), spathulenol (1.42-8.34%), ??-pinene (0.85-6.81%), ledene (0.94-6.72%), and longifonene (0.07-6.22%). The composition of the volatiles desorbed from samples from all four different areas varied qualitatively and quantitatively. All identified compounds were quantitated using total ion chromatogram peak areas. DTD is a good method for qualitative and/or quantitative analysis of complex mixtures, and in particular for quantitative analysis of plant samples, which can yield data without the traditional obligation for costly and time consuming extraction techniques

INTEGRAL discovery of persistent hard X-ray emission from the Soft Gamma Ray Repeater SGR 1806-20

We report the discovery of persistent hard X-ray emission extending up to 150 keV from the soft gamma-ray repeater SGR 1806-20 using data obtained with the INTEGRAL satellite in 2003-2004. Previous observations of hard X-rays from objects of this class were limited to short duration bursts and rare transient episodes of strongly enhanced luminosity (``flares''). The emission observed with the IBIS instrument above 20 keV has a power law spectrum with photon index in the range 1.5-1.9 and a flux of 3 milliCrabs, corresponding to a 20-100 keV luminosity of ~10^36 erg s^-1 (for a distance of 15 kpc). The spectral hardness and the luminosity correlate with the level of source activity as measured from the number of emitted bursts.Comment: 5 pages, 3 figures, Revised version accepted for publication in Astronomy and Astrophysics Letter

Comparative study of the two large flares from SGR1900+14 with the BeppoSAX Gamma-Ray Burst Monitor

We report on spectral and temporal results of the 40-700 keV observations, obtained with the Gamma-Ray Burst Monitor (GRBM) on board BeppoSAX, of the two large flares from the Soft Gamma-ray Repeater SGR1900+14 occurred on August 27, 1998 and April 18, 2001. From their intensity, fluence and duration, the first one was classified as "giant" and the second as "intermediate". The spectral results have been obtained with an improved response function of the GRBM. We find that the two events have similar spectral properties, but different temporal properties. The major difference concerns the time profiles of the light curves, whereas the lack of evidence in the 2001 flare for the erratic time variability found at high frequencies (10-1000 Hz) in the 1998 flare could be ascribed to lower counting statistics. We discuss these results in the light of the magnetar model proposed for SGR sources.Comment: 15 pages, 20 figures, accepted for publication in A&

The INTEGRAL view of the Soft Gamma-ray Repeater SGR 1806-20

We present the results obtained by INTEGRAL on the Soft-Gamma Ray Repeater SGR 1806-20. In particular we report on the temporal and spectral properties of the bursts detected during a moderately active period of the source in September and October 2003 and on the search for quiescent emission.Comment: To appear in the proceedings (ESA-SP) of the 5th INTEGRAL Workshop, "The INTEGRAL UNIVERSE", Munich, 16-20 February 200

Temporal properties of gamma-ray bursts as signatures of jets from the central engine

A comprehensive temporal analysis has been performed on the 319 brightest GRBs with T90>2s from the BATSE current catalog. The rise times, fall times, full-widths at half maximum (FWHM), pulse amplitudes and pulse areas were measured and the frequency distributions are presented here. The distribution of time intervals between pulses is not random but compatible with a lognormal distribution when allowance was made for the 64 ms time resolution and a small excess (5%) of long duration intervals that is often referred to as a Pareto-Levy tail. A range of correlations are presented on pulse and burst properties. The rise and fall times, FWHM and area of the pulses are highly correlated with each other. The time intervals between pulses and pulse amplitudes of neighbouring pulses are correlated with each other. It was also found that the number of pulses, N, in GRBs is strongly correlated with the fluence and the duration and that can explain the well known correlation between duration and fluence. The GRBs were sorted into three catagories based on N i.e. 3=25. The properties of pulses before and after the stongest pulse were compared for the three catagories of bursts. This analysis revealed that the GRBs with large numbers of pulses have narrower and faster pulses and also larger fluences, longer durations and higher hardness ratios than the GRBs with smaller numbers of pulses.Comment: 19 pages, 22 figures. Submitted to A&A July 200

Composition of Eucalyptus camaldulensis volatiles using direct thermal desorption coupled with comprehensive two-dimensional gas chromatography-time-of-flight-mass spectrometry.

The direct qualification and quantitation of the volatile organic components of four Eucalyptus camaldulensis fruit samples, obtained from different geographical areas in Turkey, is studied using a direct thermal desorption (DTD) technique coupled with comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry. It is found that the E. camaldulensis sample from Adrasan gave a slightly higher oil yield (1.18%) than the others. The number of components quantitatively identified from Adrasan, Belek, Kuyucak, and Cesme were 46, 54, 55, and 59, respectively. The main compounds found in the volatile oils were: aromadendrene (6.45-15.02%), eucalyptol (0.17-12.61%), gamma-gurjunene (8.40-10.08%), terpinolen (1.98-8.39%), spathulenol (1.42-8.34%), alpha-pinene (0.85-6.81%), ledene (0.94-6.72%), and longifonene (0.07-6.22%). The composition of the volatiles desorbed from samples from all four different areas varied qualitatively and quantitatively. All identified compounds were quantitated using total ion chromatogram peak areas. DTD is a good method for qualitative and/or quantitative analysis of complex mixtures, and in particular for quantitative analysis of plant samples, which can yield data without the traditional obligation for costly and time consuming extraction techniques

Chemical Composition of Volatile Oils from Leaves and Flowers of Sideritis congesta Using Direct Thermal Desorption - Two - Dimensional Gas Chromatography - Time - of - Flight Mass Spectrometry

Volatile oils from the leaves and flowers of Sideritis congesta, a plant endemic to Southern Anatolia, Turkey, were liberated using direct thermal desorption (DTD) and then analysed using comprehensive gas chromatography (GC × GC) coupled with time-of-flight mass spectrometry (TOF-MS). Two methods of thermal desorption are compared here; i) a manual direct cryo cooled on-column collection and focusing, and ii) a fully automated two stage carbon adsorbent thermal desorption system. 41 different volatile components were identified associated with plant leaves and 54 components for the flowers. A comparison of the flower volatiles resolved using the different thermal desorption methods indicated 43 common components, but with the cryo-cooled on-column method giving a slightly better determination. Major organic constituents observed from this species were Opinene (12.53–14.55 %), ß-pinene (17.15–25.34 %) and ô-cadinene (10.97–14.52 %). Results for manual and automated DTD methods are similar: both of them allow a fast plant volatile analysis without the costly and time consuming step of extraction or distillation. © 2008 Taylor & Francis Group, LLC

Early-Time Observations of the GRB 050319 Optical Transient

We present the unfiltered ROTSE-III light curve of the optical transient associated with GRB 050319 beginning 4 s after the cessation of gamma-ray activity. We fit a power-law function to the data using the revised trigger time given by Chincarini and coworkers, and a smoothly broken power-law to the data using the original trigger disseminated through the GCN notices. Including the RAPTOR data from Woniak and coworkers, the best-fit power-law indices are α = -0.854 ± 0.014 for the single power-law and α1 = -0.364-0.019+0.020, α2 = -0.881-0.031+0.030, with a break at tb = 418 -30+31 s for the smoothly broken fit. We discuss the fit results, with emphasis placed on the importance of knowing the true start time of the optical transient for this multipeaked burst. As Swift continues to provide prompt GRB locations, it becomes more important to answer the question, "when does the afterglow begin?" in order to correctly interpret the light curves