//////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1041 SUBJECT: Giant flare from SGR1900+14 DATE: 01/04/18 13:17:22 GMT FROM: Filippo Frontera at ITESRE CNR C.Guidorzi, E.Montanari and F.Frontera, University of Ferrara, Italy; E. Costa, G.Gandolfi, M.Feroci and L.Piro, IAS-CNR, Roma; L.Amati, TESRE, CNR, Bologna; J.J.M. in 't Zand, SRON and Astronomical Institute, Utrecht, NL; G. D'Andreta, R. Kaptein, L. Reboa, BeppoSAX Science Operation Center, report: A giant flare of SGR1900+14 was detected by BeppoSAX at 7:55:12 UT of April 18, 2001. The peak flux measured by the Gamma Ray Burst Monitor, after background subtraction and no dead time correction, is around 15400 c/s. The flare has an approximate duration of 40 s. The 5s pulsation is apparent. The Wide Field Camera #1 was switched off by rate protection at a level of 1300 c/s before the flare peak. A BeppoSAX TOO is in progress. This message can be cited. //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1043 SUBJECT: IPN Triangulation of the Giant Flare from SGR1900+14 DATE: 01/04/18 21:33:55 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the Ulysses GRB team, and E. Montanari, C. Guidorzi, F. Frontera, and M. Feroci, on behalf of the BeppoSAX GRBM team, report: Ulysses observed the giant flare reported in GCN 1041. As observed by Ulysses, this flare had a duration ~40 s, a 25-100 keV fluence ~2.6 x 10^-4 erg/cm^2, and a peak flux over 0.5 s ~1.7x10^-5 erg/cm^2 s (or about 25 and 200 times less fluence and peak flux than the giant flare of 1998 August 27). As Ulysses was in a solar proton flux, these numbers are subject to more than the usual uncertainties. Triangulation confirms that this flare is indeed from SGR1900+14 as reported in GCN 1041. The time history of this flare is quite unusual, and will be posted at ssl.berkeley.edu/ipn3/ newdata.html/010418. //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1044 SUBJECT: SGR1900+14, I-band observations DATE: 01/04/19 12:35:15 GMT FROM: Sylvio Klose at TLS Tautenburg S. Klose, B. Stecklum, and U. Laux (Thueringer Landessternwarte Tautenburg) on behalf of a larger collaboration report: We observed the field towards SGR 1900+14 in the I-band using the Tautenburg Schmidt telescope equipped with the Schmidt focus CCD camera (14 frames, 2 min exposure time each). Observations were performed on April 19, 1:12 UT - 2:19 UT, i.e., about 18 hours after the giant gamma-ray flare discovered by BeppoSAX and Ulysses (Guidorzi et al., GCN #1041; Hurley et al., GCN #1043). Of the 14 frames obtained we finally added 8 to construct an image. The other frames are affected by a cloudy sky. At the position of the fading radio source discovered after the strong outburst in 1998 (Frail et al. 1999, Nature 398, 127; see also Fig. 1 in Vrba et al. 2000, ApJ 533, L17) we detect no object down to a limiting magnitude of about I=21. This message can be cited. //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1045 SUBJECT: Possible precursor to the SGR1900+14 giant burst DATE: 01/04/20 19:48:21 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the Ulysses GRB team, and E. Montanari, C. Guidorzi, F. Frontera, and M. Feroci, on behalf of the BeppoSAX GRBM team, report: We have identified a likely precursor to the giant flare from SGR1900+14 (GCN 1041, 1043) in the Ulysses data. This event occurred on April 17, 2001, ~42184 s at Ulysses, and if it was indeed from SGR1900+14, its Earth-crossing time would have been ~42332 s. This burst was ~50 s long, and its time history resembles that of the April 18 event, although it is considerably less intense. Its 25-100 keV fluence was ~2.3x10^-5 erg/cm^2, and its peak flux over 0.5 s was ~1.5x10^-6 erg/cm^2 s. Due to a high solar proton background, these numbers are subject to more than the usual uncertainties. As SGR1900+14 was Earth-blocked at BeppoSAX, it did not observe this event, and there is no localization data available. The time history has been posted at ssl.berkeley.edu/ipn3/010417. Also, we note that the time history of the April 18 event, posted at ssl.berkeley.edu/ipn3/010418, was incorrectly labelled "Counts/ 0.5 s". The label should have read "Counts/Second". A corrected plot has been posted. Searches are underway through the Ulysses data for more possible events from this source. //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1046 SUBJECT: Chandra Observations of SGR 1900+14 DATE: 01/04/24 00:00:36 GMT FROM: Chryssa Kouveliotou at MSFC C.Kouveliotou, A. F. Tennant, M. C. Weisskopf, NASA/MSFC, report on behalf of a large SGR collaboration: Chandra observed the newly active (GCN #1041) Soft Gamma Repeater, SGR 1900+14, on April 22, 2001 starting at 4:45 UT, for 20,000 seconds. The ACIS S3 observation mode was Continuous Clocking (CC). We have fitted a spectrum to the whole data set; we find the best fit to be a single power law with spectral (photon) index of 2.9 +/- 0.1 and a hydrogen column density (NH) of (3.4 +/- 0.1)x10^22 cm^-2. We detect no black body contribution in the spectrum. The source (unabsorbed) flux is 1.1x10^-11 ergs/cm^2 s (2-10 keV), nearly identical to the quiescent source flux level. The pulse period is 5.1725 s (barycenter corrected); the pulse profile appears sinusoidal. More detailed analysis and comparison with RXTE simultaneous observations is underway. //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1047 SUBJECT: SGR 1900+14, Chandra observations DATE: 01/04/24 03:38:04 GMT FROM: Dale A. Frail at NRAO D. W. Fox and D. L. Kaplan (Caltech) report on behalf of a larger collaboration" "In response to the 18 April 2001 flare of SGR 1900+14 (GCN 1041) the Chandra X-ray Observatory has undertaken a sequence of two public 20-ksec observations of this source, on 22 and 30 April 2001. The first observation began at 04:58 UT on 22 April and was taken in continuous-clocking mode (see also GCN 1046). Examination of the light curve reveals that at least one burst was observed, 9081 s after the start of the observation. Assuming the best-fit spectral parameters for the observation (see below), the peak 1-s flux of this burst was of order 5e-10 erg cm^-2 s^-1 (0.5-10 keV). Spectral fits to the full background-subtracted data set allow for at least two emission models. A power-law plus absorption model has best-fit parameters of N_H = 3.18(2)e22 cm^-2, photon index alpha = 2.70(1), and unabsorbed 0.5-10 keV flux of 4.20(4)e-11 erg cm^-2 s^-1. A power-law plus blackbody and absorption model has best-fit parameters of N_H = 2.56(2)e22 cm^-2, photon index alpha = 1.88(1), blackbody temperature kT = 0.532(3) keV, unabsorbed 0.5-10 keV flux of 2.17(3)e-11 erg cm^-2 s^-1, and flux fraction for the blackbody component of 29% (0.5-10 keV). The addition of the blackbody component is not supported by an F-test (65% confidence level) but is consistent with models in the literature (Perna et al. 2001, astro-ph/0103273). Analysis of the RXTE PCA data may help to clarify the presence or absence of the blackbody component, as the PCA count rates inferred from the two models given above differ by 50%. No narrow spectral features are apparent. The two-sigma upper limit to the flux of a persistent 0.2-keV FWHM emission line in the 5-7 keV range is 1e-5 photons cm^-2 s^-1. This message may be cited." //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1048 SUBJECT: Chandra Observations of SGR 1900+14 DATE: 01/04/24 22:07:48 GMT FROM: Chryssa Kouveliotou at MSFC C. Kouveliotou, A. F. Tennant, M. C. Weisskopf, NASA/MSFC, report on behalf of a larger SGR collaboration: We have examined our overlapping Chandra/RXTE observations of SGR 1900+14 (RXTE TOO, P. Woods, PI). We cannot verify the burst reported in GCN #1047. The source was occulted by the earth at the time in question. We confirm the burst in the Chandra data at approximately 7:15:25 UT. The burst duration appeared to be 0.35 seconds during which 14 counts were recorded (ignoring pile-up). Thus the peak count rate was 65 times the quiescent rate. Adopting the quiescent source spectrum (GCN # 1046), we estimate the peak flux in the 2-10 keV band to be 7.2 x 10^-10 ergs/cm^2 s (2.9 x 10^-9 ergs/cm^2 s in 0.5-10.0 keV). We would like to add a clarification regarding the persistent source flux values in the two GCNs (1046, 1047). Our flux estimates are for the 2-10 keV band to facilitate comparison with data from other satellites; when we expand the energy range to 0.5-10 keV (as in GCN 1047) we find similar values for the quiescent flux. This message can be cited. _____________________________________________ Chryssa Kouveliotou NSSTC, SD-50, Rm 2057 320 Sparkman Drive, Huntsville, AL 35805 tel: 256 961 7604 fax: 256 961 7215 //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1049 SUBJECT: SGR 1900+14: Detection of extended X-ray emission DATE: 01/04/26 00:05:20 GMT FROM: Derek Fox at CIT D. W. Fox and D. L. Kaplan (Caltech) report: "Analysis of data from the 22 April 2001 Chandra observation (GCN 1046, 1047), barycenter-corrected with the preliminary CXC ephemeris, reveals that the source emission is pulsed at a period of P = 5.17288(5) s with a pulse strength of 14.3(2)% RMS that remains constant (within errors) throughout the observation. Separation of the source photons into "on-pulse" and "off-pulse" components of 1/3 cycle each reveals that the off-pulse spatial distribution is significantly broader than the on-pulse distribution. Since the observation is taken in continuous-clocking mode, we can only make this determination in one dimension. Nonetheless, the sigma-widths of the one-dimensional Gaussian PSFs are 0.98(1) arcsec for on-pulse photons and 1.08(2) arcsec for off-pulse photons, different at >5-sigma level. We attribute this difference in widths to the presence of an underlying X-ray nebula." //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1050 SUBJECT: Millimeter observation of SGR 1900+14 DATE: 01/04/26 08:55:11 GMT FROM: Michael Bremer at IRAM Grenoble Millimeter observations of SGR 1900+14 ---------------------------------------- M. Bremer, IRAM (Grenoble) and A.J. Castro-Tirado, IAA-CSIC (Granada) and LAEFF-INTA (Madrid) report: We have observed the position of the proposed SGR 1900+14 radio counterpart reported by Frail et al. 1999 (Nature 398, 127) with the IRAM Plateau de Bure Interferometer on April 24, 2001 between UT 1:13 - 3:04 (i.e. approximately six days after the giant flare reported by Guidorzi et al. in GCN 1041). The source was not detected. The following fluxes and 1-sigma errors (corrected for atmospheric decorrelation) were measured on the phase center: 92.772 GHz: -0.64 +- 0.60 mJy/beam (beam: 10.4" x 5.2" by PA=-55 deg.) 217.829 GHz: -2.7 +- 2.8 mJy/beam (beam: 4.5" x 2.3" by PA=-47 deg.) No bright sources were detected within the field of view of the primary beams (53" and 23", respectively). //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1052 SUBJECT: SGR 1900+14: Correction to GCN 1049 DATE: 01/04/27 09:44:20 GMT FROM: Derek Fox at CIT D. W. Fox and D. L. Kaplan (Caltech) report: "The PSF parameters quoted in GCN 1049 for the 22 April 2001 Chandra observation of SGR 1900+14 are in units of ACIS pixels, not arcseconds as reported. The correct on- and off-pulse PSF sigma values for the best-fit Gaussians are 0.98(1) and 1.08(2) pixels, or 0.480(5) and 0.53(1) arcseconds, respectively." //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1053 SUBJECT: SGR1900+14 DATE: 01/04/27 15:49:00 GMT FROM: Kevin Hurley at UCBerkeley/SSL K. Hurley, on behalf of the Ulysses GRB team, E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team, and E. Montanari, C. Guidorzi, F. Frontera, and M. Feroci, on behalf of the BeppoSAX GRBM team, report: We have completed a search through the data of the Ulysses GRB experiment for possible bursts from SGR1900+14 on 2000 April 17 and 18. Although numerous candidate events were found, none has been confirmed, with the exception of the April 18 giant flare (GCN 1043). In particular, the possible precursor on April 17 (GCN 1045) was not found in the Konus-Wind data. Therefore we believe that this event and the other candidates do not originate from the SGR. //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1054 SUBJECT: SGR1900+14 - correction DATE: 01/04/27 15:52:43 GMT FROM: Kevin Hurley at UCBerkeley/SSL In GCN 1053, the date should read 2001 April 17 and 18, not 2000 April 17 and 18. //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1055 SUBJECT: BeppoSAX/NFI Follow-up Observation of SGR 1900+14 DATE: 01/04/27 16:26:03 GMT FROM: Marco Feroci at IAS/CNR Frascati BeppoSAX/NFI Follow-up Observation of SGR 1900+14 M. Feroci (IAS/CNR, Roma) and S. Mereghetti (IFC/CNR, Milano), on behalf of a larger SGR collaboration, and G. Gandolfi, L. Piro and E. Costa (IAS/CNR, Roma), on behalf of the BeppoSAX Team, report: "A ToO observation of SGR1900+14 was carried out with the BeppoSAX Narrow Field Instruments starting on April 18, 15:10 UT, less than 8 hours after the large flare reported in GCN #1041. Intense bursting activity is present during the 28 hr long observation. After removing the numerous short bursts, a significant flux decay is visible in the MECS and LECS light curves. By using our data and the Chandra 2-10 keV flux (GCN #1046) we find that the decay can be reasonably well described by a power law with index ~-0.6. There is also evidence for a spectral softening correlated with the intensity decrease. The average spectrum (after removal of the bursts) can be fit by a power law with photon index 2.6+/-0.1 and NH=(4.3 +/-0.3)x10^22 cm^-2. The average 2-10 keV flux during the whole BeppoSAX observation is 2.9x10^-11 erg/cm^2/s (unabsorbed). The bursts have a significantly harder spectrum (power law photon index ~0 in the 2-10 keV range). Pulsations, with a nearly sinusoidal light curve and a modulation of about 21%, are clearly detected at the barycentered period P=5.17277(1) s. When compared with the value measured with Chandra about 3 days later (GCN #1049), this yields a dP/dt ~ (4.1 +/- 1.9)x10^-10 s/s. An additional BeppoSAX/NFI observation will start on April 29, 20:30 UT." This message may be cited. //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1056 SUBJECT: SGR 1900+14 : RXTE observations DATE: 01/04/30 17:14:25 GMT FROM: Peter Woods at UAH/MSFC P. Woods (USRA/NSSTC), C. Kouveliotou (NASA/MSFC), and E. Gogus (UAH/NSSTC) report on behalf of a larger collaboration. ToO observations of SGR 1900+14 with the Rossi XTE were initiated on April 19, 2001 and have continued through April 28. Thus far, more than 60 bursts have been detected in ~110 ks of exposure time. Coincidentally, a short (~10 ks) observation of SGR 1900+14 was performed on April 14 (4 days prior to the flare) as part of our ongoing monitoring campaign. We find no burst activity within this observation. For the latest observation on April 28, 4 bursts were recorded in one RXTE orbit, thus the source remains burst active. Selecting a 6 day subset of these observations for which we have spacecraft ephemeris information, we have phase connected the data and measured both a period and period derivative. We chose our epoch (MJD 52021.3 TDB) to coincide with the first Chandra observation. We measure a barycentric period of 5.1728219(14) s where the number given in the parentheses marks the 1 sigma error in the least significant digits. The period derivative is found to be +1.58(22) X 10E-10 s/s. The ephemeris we find agrees well with the measured periods reported for both the Chandra (GCN #1049) and BeppoSAX (GCN #1055) observations. Furthermore, the magnitude of the spindown found here is well within the range of historical spindown rates measured for this SGR. This message may be cited. //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1057 SUBJECT: SGR 1900+14: No evidence of extended X-ray emission DATE: 01/04/30 20:52:42 GMT FROM: Derek Fox at CIT D. W. Fox and D. L. Kaplan (Caltech) report: "Our earlier report of a pulse phase-variable PSF width in Chandra observations of SGR 1900+14 (GCN 1049) was in error. Appropriate treatment of the background counts relative to source counts reveals that the one-dimensional PSF is consistent with a Gaussian of fixed standard deviation equal to 0.41(1) arcseconds throughout the pulse phase. We therefore retract our claim of detection of extended X-ray emission in this data." //////////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1060 SUBJECT: X-ray precursors to the large flare from SGR 1900+14 DATE: 01/05/04 17:26:12 GMT FROM: Marco Feroci at IAS/CNR Frascati X-ray precursors to the large flare from SGR 1900+14 M. Feroci (IAS/CNR, Rome), J.J.M. in 't Zand (Astronomical Institute, Utrecht University and SRON), P. Soffitta (IAS/CNR, Rome), K. Hurley (UCB, California), F. Frontera (Univ. Ferrara and TESRE/CNR, Bologna) and E. Mazets (IOFFE, S. Petersburg), report: "A high-time resolution analysis has been performed of the BeppoSAX Wide Field Camera data of SGR 1900+14 taken on April 18, 2001, when the most recent giant flare was detected (Guidorzi et al., GCN 1041 and IAUC 7611). The data cover a short intermediate pointing of Wide Field Camera unit 1 between two scheduled targets. The observation started 2780 s before the giant flare and ended with the automatic switch off due to that flare. The observation was interrupted when BeppoSAX traversed the SAA, from 2282 till 1052 s before the giant flare. The analysis revealed the presence of 3 short X-ray precursors, occurring 2537, 755, and 444 s before the giant flare (respectively, 25975, 27757 and 28068 s UT), with durations of 100, 125 and 55 ms, peak fluxes in excess of 20 Crab units (2-28 keV), and 9-28/2-9 keV spectral hardness ratios that are consistent with power laws with photon indices between roughly 0.5 and 1.2. None of the precursors was detected in the gamma-ray data from the BeppoSAX/GRBM, the gamma-ray burst detector on Ulysses, and from Konus on Wind."