//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30120 SUBJECT: Swift Detection of probable new Swift SGR J1555.2-5402 DATE: 21/06/03 10:25:32 GMT FROM: David Palmer at LANL D.M. Palmer (LANL), P.A. Evans (U. Leicester), N.P.M. Kuin (MSSL/UCL), and K.L. Page (U. Leicester) report on behalf of the Swift Team: At 09:45:46 UT on 2021-06-03, the Swift Burst Alert Telescope (BAT) triggered and located an unknown burst source (trigger=1053220). Swift slewed immediately to the source. The BAT on-board calculated location is RA, Dec 238.819, -54.046 which is RA(J2000) = 15h 55m 17s Dec(J2000) = -54d 02' 46" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT lightcurve shows a single-bin (64 ms) spike with a nominal peak of 2000 counts per second. However, the BAT trigger timescale was very short (8 ms) and moderately intense (29 sigma in count rate), indicating a very short spike emission. The XRT began observing the field at 09:47:23.3 UT, 96.8 seconds after the BAT trigger. No source was detected in the 2.5-s promptly available image. We are waiting for the full dataset to detect and localise the XRT counterpart. UVOT took a finding chart exposure of 61 seconds with the White filter starting 100 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the large expected extinction. The fast lightcurve shape, combined with the source's location near the Galactic plane (lon, lat = 327.90, -0.34) leads us to the conclusion that this is a new SGR, which we name Swift SGR J1555.2-5402 based on the BAT position. More information on this source will be provided once the ground pass data has been analyzed. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30121 SUBJECT: NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402 DATE: 21/06/03 16:59:30 GMT FROM: Nanda Rea at CSIC-IEEC F. Coti Zelati, A. Borghese, N. Rea (ICE-CSIC), G. L. Israel (INAF-OAR), P. Esposito (IUSS Pavia), T. Enoto (RIKEN), K. Gendreau (NASA/GSFC) S. Campana (INAF-OAB) on behalf of a larger collaboration On 2021 June 03 at 09:45:46 UT, the Swift Burst Alert Telescope (BAT) triggered on a short X-ray burst from a direction close to the Galactic plane. The short duration of the burst led to its tentative association to a newly discovered magnetar, SGR J1555.2-5402 (GCN #30120). NICER started observing the field at 12:32:00 UT, and Swift/XRT observed at 10:53:43 UT, only a few hours after the Swift/BAT trigger. We report on the preliminary analysis of the data available so far, which total to an exposure time of about 1.6 ks for NICER, and 1.6ks for Swift/XRT. Swift/XRT finds a new X-ray source at a position (3.67 arcsec error) of: RA (2000) = 15 55 08.556, Dec (2000) -54 03 38.74 SGR J1555.2-5402 is detected in NICER at a count rate of about 4.5 counts/s (not background-subtracted) in the energy range 1-8 keV. We also detected coherent pulsations at high confidence level at a period of P=3.8611(1) s (uncertainty in parenthesis at 1 sigma; we used event times not corrected for the solar system barycentre), which confirms that the short burst was indeed emitted by a new magnetar. Results from a more detailed analysis will be reported later on. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30124 SUBJECT: SGR J1555.2-5402: Swift-BAT refined analysis DATE: 21/06/04 15:58:06 GMT FROM: Amy Lien at GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), (i.e. the Swift-BAT team): Using the data set from T-240 to T+100 sec from the recent telemetry downlink, we report further analysis of SGR J1555.2-5402 (trigger #1053220) (Palmer et al., GCN Circ. 30120). The BAT ground-calculated position is RA, Dec = 238.782, -54.065 deg which is RA(J2000) = 15h 55m 07.6s Dec(J2000) = -54d 03' 55.6" with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 89%. The 1-ms binned mask-weighted light curve shows a multi-peaked structure that starts at ~T-0.003 s and ends at ~T+0.008 s. The two peaks occur at ~T+0.003 s and ~T+0.006 s, respectively. T90 (15-350 keV) estimated from the 1-ms binned light curve is 0.011 +- 0.003 sec (estimated error including systematics). The time-averaged spectrum from T+0.00 to T+0.008 sec can be fitted by a simple power-law model. The power law index of the time-averaged spectrum is 2.45 +- 0.31 (chi squared 25.37 for 57 d.o.f.). The fluence in the 15-150 keV band is 9.5 +- 2.0 x 10^-9 erg/cm2. A single blackbody fit to the time-averaged spectrum shows the blackbody temperature of 6.9 +- 1.2 keV (chi squared 23.26 for 57 d.o.f.). All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/1053220/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30125 SUBJECT: Fermi GBM Sub-Threshold Detection of new Swift SGR J1555.2-5402 DATE: 21/06/04 17:34:43 GMT FROM: Cori Fletcher at USRA C. Fletcher (USRA) reports on behalf of the Fermi-GBM Team: Swift-BAT detected Swift SGR J1555.2-5402 at 09:45:46 UT (GCN 30120). There was no Fermi-GBM onboard trigger around the event. An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified no counterparts. The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals was run from +/-30 s around the BAT trigger time. A transient source was identified whose most significant timescale according to the automated search is 64 ms, with a false alarm rate of 5.8e-05 Hz and a location consistent with the Swift-BAT event, using the standard search protocol with a S/N of 6. The event was found to be even more significant (S/N of 12) on the 8 ms timescale, but an associated false alarm rate is currently not available on the 8 ms timescale. The GBM targeted search event was found with the highest significance with a "soft" spectrum (Band function with Epeak = 70 keV, alpha = -1.9, beta = -3.7). [1] Goldstein et al. 2019 arXiv:1903.12597 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30140 SUBJECT: GECAM Sub-Threshold Detection of new magnetar Swift SGR J1555.2-5402 DATE: 21/06/07 08:25:44 GMT FROM: Ce Cai at IHEP C. Cai, S. L. Xiong, Y. Huang, S. L. Xie, S. Xiao, Y. Zhao, J. C. Liu, C. Y. Li, Y. Q. Zhang, W. C. Xue, C. Zheng, Z. W. Guo, X. Y. Zhao, Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo, J. J. He, B. Li, C. Li, J. H. Li, Q. X. Li, X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang, J. Y. Liao, J. C. Liu, X. J. Liu, Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma, G. Ou, W. X. Peng, R. Qiao, D. L. Shi, J. Y. Shi, L. M. Song, X. Y. Song, G. X. Sun, X. L. Sun, Y. L. Tuo, C. W. Wang, J. Z. Wang, P. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, S. Yang, M. Yao, Q. B. Yi, B. X. Zhang, C. Y. Zhang, D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang, K. Zhang, P. Zhang, S. N. Zhang, Z. Zhang, S. Y. Zhao, S. J. Zheng, X. Zhou (IHEP), report on behalf of GECAM team: Regarding the new magnetar SGR J1555.2-5402 discovered by Swift/BAT (GCN #30120), there was no GECAM in-flight trigger or on-ground automated blind search trigger around the BAT trigger time (2021-06-03T09:45:46). Thus, we implemented a targeted search for sub-threshold burst signals from +/-35 s around BAT trigger time, using an improved coherent search algorithm (C. Cai, In preparation, L. Blackburn et al.). From the targeted search, we found a short soft burst at 2021-06-03T09:45:46.670, with the most significant timescale of 10 ms. Its location is consistent with the Swift/BAT position (GCN #30120) and the spectrum is soft (Band function with Epeak = 70 keV, alpha = -1.9, beta = -3.7). We conclude this bursts is from SGR J1555.2-5402. The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/76412746.67energys.pdf Please note that all GECAM results here are preliminary. The final analysis will be published in journal papers or GECAM online catalog. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time), which was funded by the Chinese Academy of Sciences (CAS). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30753 SUBJECT: Fermi GBM observation of a burst from SGR J1555.2-5402 DATE: 21/09/03 14:54:10 GMT FROM: Oliver J Roberts at USRA/NASA O.J. Roberts (USRA/NASA-MSFC), R. Dunwoody (UCD), J. Mangan (UCD) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 05:20:49.405 UT on 27 August 2021, the Fermi Gamma-Ray Burst Monitor triggered on an SGR-like burst from the direction of SGR J1555.2-5402 (trigger 651734454/bn210827223). The SGR burst was also detected by Swift-BAT (Palmer, 2021, ATel 14887). The on-ground calculated location, using the Fermi GBM trigger data, is consistent with the Swift position and known position of the SGR. The angle from the Fermi LAT boresight is 21 degrees. The burst has a duration of about 0.024 s (8-200 keV). The time-averaged spectrum from T+0.384s to T0+0.408s is best fit by a by a power law function with an exponential high-energy cutoff. The power law index is -0.41 +/- 0.65 and the cutoff energy, parameterized as Epeak, is 32 +/- 4 keV. The event fluence (8-200 keV) from T0+0.384s to T0+0.408s is (3.123 +/- 0.336)E-08 erg/cm^2. The average photon flux in the 8-200 keV band during this period is 31 +/- 3 ph/s/cm^2. The spectral analysis results presented above are preliminary. For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30787 SUBJECT: GECAM observation of a burst from SGR J1555.2-5402 DATE: 21/09/09 14:49:12 GMT FROM: Zhao Yi at POLAR Yi Zhao, S. Xiao, S. L. Xiong, L. Lin, C. Cai, J. J. He, Y. Huang, Z. W. Guo, C. Y. Li, X. B. Li, J. C. Liu, X. Y. Song, C. W. Wang, P. Wang, S. L. Xie, W. C. Xue, Q. B. Yi, Y. Q. Zhang, G. Y. Zhao, X. Y. Zhao, C. Zheng, Y. Q. Du, D. Y. Guo, J. Liang, F. J. Lu, Q. Luo, X. Ma, W. X. Peng, R. Qiao, L. M. Song, J. Wang, H. Wu, P. Zhang, S. N. Zhang, X. L. Zhang, Z. Zhang, S. J. Zheng (IHEP), report on behalf of GECAM team: During the commissioning phase, GECAM-B was triggered on-ground by a bright short burst from SGR J1555.2-5402 at 2021-09-07T19:15:21.100 UTC (T0), which was also detected by Fermi/GBM. According to the GECAM-B light curves in about 15-60 keV, this burst mainly consists of a single pulse with T90 of 18 ms measured from T0-0.014 s. The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/SGR20210907T191521.100-Lc.png Since this burst has very few counts registered on GECAM-B detectors, the location given by GECAM-B alone is quite coarse but broadly consistent with SGR J1555.2-5402. According to our multiple-mission joint location pipeline (S. Xiao et al., accepted by ApJ) using GECAM-B and Fermi/GBM data, this burst is localized to an annulus which is very consistent with SGR J1555.2-5402. The GECAM-GBM joint location could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/SGR20210907T191521.100-JointLoc.png Considering these results stated above and some activities reported recently, we conclude that this burst is from SGR J1555.2-5402. Please note that all GECAM results here are preliminary. The final analysis will be published in journal papers or GECAM online catalog. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time), which was funded by the Chinese Academy of Sciences (CAS). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30922 SUBJECT: GECAM observation of a burst from SGR J1555.2-5402 DATE: 21/10/05 14:17:18 GMT FROM: Y Q Zhang at IHEP Y. Q. Zhang, S. L. Xiong, S. Xiao, C. Cai, X. Y. Zhao, Y. Huang, X. Y. Song, J. C. Liu, S. L. Xie, Y. Zhao, Z. W. Guo, C. Zheng, W. C. Xue, C. Y. Li, C. W. Wang, Q. B. Yi, B. X. Zhang, P. Zhang, W. X. Peng, R. Qiao, D. Y. Guo, X. B. Li, X. Ma, P. Wang, J. Wang, Z. Zhang, S. J. Zheng, W. Chen, J. J. He, G. Y. Zhao, Y. Q. Du, H. Wu, J. Liang, Q. Luo, X. L. Zhang, L. M. Song, F. J. Lu, S. N. Zhang (IHEP), report on behalf of GECAM team: During the commissioning phase, GECAM-B was triggered on-ground by a bright short burst from SGR J1555.2-5402 at 2021-10-04T00:13:14.700 UTC (T0). According to the GECAM-B light curves in about 10-50 keV, this burst mainly consists of a single pulse with a duration about 30 ms.The location given by GECAM-B alone is consistent with SGR J1555.2-5402 within the error. GECAM-B localized this burst to the following position (J2000): Ra: 241.96 deg Dec: -55.45 deg Err: 9.01 deg (1-sigma, statistical only) The current systematic error of location is estimated to be several degrees which could be minimized by the ongoing calibration. The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/utn211004_001314_GECAMb.png According to our multiple-mission joint location pipeline (S. Xiao et al., accepted by ApJ) using GECAM-B and Fermi/GBM data, this burst is localized to an annulus which is very consistent with SGR J1555.2-5402. The GECAM-GBM joint location could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/SGR20211004T001314.700-JointLoc.png Please note that all GECAM results here are preliminary. The final analysis will be published in journal papers or GECAM online catalog. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time), which was funded by the Chinese Academy of Sciences (CAS). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 30985 SUBJECT: GECAM detection of a short burst probably from SGR J1555.2-5402 DATE: 21/10/25 03:44:59 GMT FROM: Ce Cai at IHEP C. Cai, S. Xiao, Yi Zhao, S. L. Xiong, J. J. He, Y. Huang, Z. W. Guo, C. Y. Li, X. B. Li, J. C. Liu, X. Y. Song, C. W. Wang, P. Wang, S. L. Xie, W. C. Xue, Q. B. Yi, Y. Q. Zhang, G. Y. Zhao, X. Y. Zhao, C. Zheng, Y. Q. Du, D. Y. Guo, J. Liang, F. J. Lu, Q. Luo, X. Ma, W. X. Peng, R. Qiao, L. M. Song, J. Wang, H. Wu, P. Zhang, S. N. Zhang, X. L. Zhang, Z. Zhang, S. J. Zheng (IHEP), report on behalf of GECAM team: During the commissioning phase, GECAM-B was triggered in-flight by a bright short burst (trig# 88823384) at 2021-10-25T01:09:44.250 UTC (T0), Its alert data was promptly downlinked to the ground through the short message service of BeiDou Navigation Satellite System (BDS). The time latency of the first BeiDou message relative to the trigger time is about 1 minute. According to the BDS alert data, this burst mainly consists of a single pulse with a duration of about 50 ms. Using the light curves and spectrum in the BDS alert data, GECAM-B localized this burst to the following position (J2000): Ra: 244.40 deg Dec: -64.997 deg Err: 17.63 deg (1-sigma, statistical only) The current systematic error of location is estimated to be several degrees. This location is consistent with SGR J1555.2-5402 within the error. The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_88823384.png As the detailed science data are downloaded, all analyses would be improved. Please note that all GECAM results here are preliminary. The final analysis will be published in journal papers or GECAM online catalog. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time), which was funded by the Chinese Academy of Sciences (CAS). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31397 SUBJECT: GECAM observation of a burst from SGR J1555.2-5402 DATE: 22/01/07 09:32:07 GMT FROM: Y Q Zhang at IHEP Y. Q. Zhang, S. Xiao, S. L. Xiong, C. Cai, P. Zhang, C. Y. Li, S. L. Xie, X. Y. Zhao, Y. Huang, X. Y. Song, J. C. Liu, Y. Zhao, Z. W. Guo, C. Zheng, W. C. Xue, C. W. Wang, Q. B. Yi, B. X. Zhang, W. X. Peng, R. Qiao, D. Y. Guo, X. B. Li, X. Ma, L. M. Song, P. Wang, J. Wang, Z. Zhang, S. J. Zheng, W. Chen, J. J. He, G. Y. Zhao, Y. Q. Du, H. Wu, J. Liang, Q. Luo, X. L. Zhang, H. M. Zhang, Z. H. An, M. Gao, K. Gong, B. Li, C. Li, J. H. Li, X. Q. Li, Y. G. Li, X. H. Liang, X. J. Liu, Y. Q. Liu, X. L. Sun, Y. L. Tuo, J. Z. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, S. Yang, C. Y. Zhang, D. L. Zhang, Fan Zhang, Fei Zhang, X. Zhou, F. J. Lu, S. N. Zhang (IHEP) report on behalf of GECAM team: During the commissioning phase, GECAM-B was triggered in-flight by a bright short burst from SGR J1555.2-5402 at 2022-01-06T13:33:47.500 UTC (T0). According to the GECAM-B light curves in about 15-65 keV, this burst mainly consists of a single pulse with a duration about 100 ms. The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_95175227.png GECAM-B localized this burst to the following position (J2000): Ra: 261.9 deg Dec: -46.7 deg Err: 13.4 deg (1-sigma, statistical only) The current systematic error of location is estimated to be several degrees which could be minimized by the ongoing calibration. The location given by GECAM-B alone is consistent with SGR J1555.2-5402 within the error. In addition, according to our multiple-mission joint analysis system (ETJASMIN, S. Xiao et al., submitted to MNRAS, S. Xiao et al., 2021, ApJ, 920 43) using GECAM-B and Fermi/GBM public data, this burst is localized to an annulus which is very consistent with SGR J1555.2-5402. The GECAM-GBM joint location could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/SGR20220106T133347.500-JointLoc.png Please note that all GECAM results here are preliminary. The final analysis will be published in journal papers or GECAM online catalog. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time), which was funded by the Chinese Academy of Sciences (CAS).