September 2021 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 28790] GRB 210927A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 654396242)
by GCN Circulars 28 Sep '21

28 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30893 SUBJECT: GRB 210927A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 654396242) DATE: 21/09/28 20:28:28 GMT FROM: Shreya Anand at GROWTH Caltech <sanand(a)caltech.edu> Shreya Anand (Caltech), Tomas Ahumada (UMD), Harsh Kumar (IITB), Michael Coughlin (UMN), Ana Sagues-Carracedo (OKC), Mansi M. Kasliwal (Caltech), Erik Kool (OKC), �Simeon Reusch (DESY), Robert Stein (DESY), Igor Andreoni (UMD), Varun Bhalerao (IITB), Albert Kong (NTHU), Leo Singer(NASA/GSFC), Jannis Necker (DESY), and Sven Weimann (DESY) on behalf of the Zwicky Transient Facility (ZTF) collaboration We observed the localization region of the short GRB 210927A (trigger 654396242) detected by the Gamma-Ray Burst Monitor (GBM) on the Fermi satellite with the Palomar 48 inch telescope equipped with the 47 square degree Zwicky Transient Facility (ZTF) camera. We obtained a series of g- and r-band images covering 470 square degrees beginning at 02:32 UT on 2021 Sept. 27 (1:38 hours after the burst trigger time) and repeating the same observing plan the next night. This corresponds to ~44% of the probability enclosed in the Earth-occultation corrected GRB localization map (GCN 30885). Each exposure was 240 seconds, reaching g-band and r-band median depths of 22.1 mag and 21.9 mag respectively for the first night and 21.4 mag and 21.3 mag for the second night. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC (Masci et al. 2019). We queried the ZTF alert stream using Kowalski (Duev et al. 2019). We required at least 2 detections separated by at least 15 minutes to select against moving objects. Furthermore, we cross-match our candidates with the Minor Planet Center to flag known asteroids, reject stellar sources (Tachibana and Miller 2018), and apply machine learning algorithms (Mahabal et al. 2019). We require that no spatially coincident ZTF alerts were issued before the detection time of the GBM trigger. We also require sources to fade faster than 0.3 mag/day to be of interest. The candidates within the 90% probability contour of the GRB localization map that pass these selection criteria as well as human vetting are presented in the table below. The filter, magnitude and MJD columns correspond to the ZTF first alert, while the Decline Rate (D.R) is in [mag/day]. The first four of these candidates also passed the ZTF Realtime Search and Triggering pipeline (Andreoni et al. 2021), which identifies rapidly-evolving candidates in the ZTF alert stream. +----------------------------------------------------------------------------------------------------------------------+ | ZTF Name | IAU Name | RA (deg) | DEC (deg) �| �r-band Mag | magErr �| D.R. [mag/day] | Notes � �| +----------------------------------------------------------------------------------------------------------------------+ ZTF21acdvumo | AT2021zwo | 244.806185 | 10.4431253 | 21.40 | 0.12 | D.R. g-band = 0.38 | (a)(1) ZTF21acdvuvw | AT2021zwp | 234.359624 | 21.0864387 | 21.10 | 0.14 | D.R. r-band = 0.43 | (a)(2) ZTF21acdvwoe | AT2021zwq | 249.160939 | 11.5012227 | 21.15 | 0.13 | D.R. r-band = 0.35 | (b) ZTF21acdwbpx | AT2021zwr | 258.470967 | 7.9687908 �| 20.85 | 0.13 | D.R. r-band = 0.73 | (b) ZTF21acdwctm | AT2021zws | 267.270437 | -3.3173181 | 20.95 | 0.10 | D.R. r-band = 0.37 | (c) +----------------------------------------------------------------------------------------------------------------------+ Notes: (a) offset from a galaxy (b) PSF-like based on Legacy Survey (LS) DR9 classification (c) hostless; low galactic latitude b=12.26; D.R. obtained with GROWTH-India telescope photometry (1) LS phot-z = 0.253 +/- 0.099 (2) LS phot-z = 0.116 +/- 0.217 ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski (Duev et al. 2019). GROWTH India telescope is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA). GROWTH-India project is supported by SERB and administered by IUSSTF, under grant number IUSSTF/PIRE Program/GROWTH/2015-16 and IUCAA.

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[vsnet-grb-info 28789] GRB 210925B: AstroSat CZTI detection
by GCN Circulars 28 Sep '21

28 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30892 SUBJECT: GRB 210925B: AstroSat CZTI detection DATE: 21/09/28 13:24:23 GMT FROM: Gaurav Waratkar at IIT,Bombay <gauravwaratkar(a)iitb.ac.in> V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed detection of a long GRB 210925B for which the IPN triangulation (Hurley et al., GCN 30890) was reported. The source was clearly detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2021-09-25 01:20:09.75 UT. The measured peak count rate associated with the burst is 887 (+190, -97) cts/s above the background in the combined data of four quadrants, with a total of 1482 (+214, -230) cts. The local mean background count rate was 471 (+5, -9) cts/s. Using cumulative rates, we measure a T90 of 6.3 (+1.9, -2.0) s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

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[vsnet-grb-info 28788] IceCube-210922A: SMA observation for the JCMT candidate
by GCN Circulars 28 Sep '21

28 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30891 SUBJECT: IceCube-210922A: SMA observation for the JCMT candidate DATE: 21/09/28 07:10:02 GMT FROM: Kuiyun Huang at CYCU <kuiyun(a)gmail.com> Y. Urata, G. Petitpas on behalf of a larger collaboration We observed the JCMT source (GCN 30882) using SMA. The SMA 230GHz observation was started at 2021 Sep 27, 15:21 (UT). The JCMT source was clearly identified at 04h02m05.304s -04d24m28.14s (0.5”) with ~17 mJy/beam. The position is consistent with the cataloged IR source (WISEA J040205.29-042428.5). The radio source, NVSS J040205-042434 is also counterpart when we consider the margin of position error. Further detailed multi-wavelength investigations are encouraged. We would like to thank SMA staff.

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[vsnet-grb-info 28787] IPN triangulation of GRB 210925B
by GCN Circulars 27 Sep '21

27 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30890 SUBJECT: IPN triangulation of GRB 210925B DATE: 21/09/27 18:08:46 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, A. Ridnaia, S. Golenetskii, D. Frederiks, D. Svinkin, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi-GBM team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report: The long-duration GRB 210925B was detected by Fermi (GBM trigger 654225613), Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), and Swift-BAT at about 4809 s UT (01:20:09). The burst was outside the coded field of view of the BAT. We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 48.817 (03h 15m 16s) -52.863 (-52d 51' 45") Corners: 47.551 (03h 10m 12s) -53.723 (-53d 43' 21") 50.006 (03h 20m 01s) -52.058 (-52d 03' 29") 50.027 (03h 20m 06s) -51.978 (-51d 58' 41") 47.579 (03h 10m 19s) -53.644 (-53d 38' 39") --------------------------------------------- The error box area is 335 sq. arcmin, and its maximum dimension is 2.3 deg (the minimum one is 2.5 arcmin). The Sun distance was 113 deg. This box may be improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB210925_T04810/IPN/ The time history and spectrum will be given in forthcoming GCN Circulars.

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[vsnet-grb-info 28786] GRB 210926A: AstroSat CZTI detection
by GCN Circulars 27 Sep '21

27 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30889 SUBJECT: GRB 210926A: AstroSat CZTI detection DATE: 21/09/27 13:36:09 GMT FROM: Gaurav Waratkar at IIT,Bombay <gauravwaratkar(a)iitb.ac.in> P. Sawant (IUCAA), G. Waratkar (IITB), V. Prasad (IUCAA), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed detection of a long GRB 210926A, which was also detected by GECAM (C. Zheng et al., GCN 30886). The source was clearly detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2021-09-26 20:52:27.5 UT. The measured peak count rate associated with the burst is 250 (+51, -16) cts/s above the background in the combined data of four quadrants, with a total of 3971 (+446, -463) cts. The local mean background count rate was 480 (+3, -3) cts/s. Using cumulative rates, we measure a T90 of 26 (+6, -5) s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2021-09-26 20:52:30.9 UT. The measured peak count rate is 262 (+73, -38) cts/s above the background in the combined Veto data of four quadrants, with a total of 3091 (+703, -866 cts. The local mean background count rate was 1512 (+5, -4) cts/s. We measure a T90 of 25 (+14, -10) s from the cumulative Veto light curve. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.

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[vsnet-grb-info 28785] GRB 210919A: iTelescope T-11 upper limits
by GCN Circulars 27 Sep '21

27 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30888 SUBJECT: GRB 210919A: iTelescope T-11 upper limits DATE: 21/09/27 09:23:47 GMT FROM: Takanori Sakamoto at AGU <tsakamoto(a)phys.aoyama.ac.jp> K. Hasuda, T. Sakamoto (AGU) We observed the field of GRB 210919A detected by Swift (Tohuvavohu et al., GCN Circ. 30846) with the iTelescope.Net (http://www.itelescope.net) T11 (Planewave 20" CDK) telescope located at the New Mexico Skies Observatory (NM, USA). 59 images of 60 sec exposures were taken in the R filter starting from September 21 on 10:04:47 (UT) about 2.4 days after the trigger and stopped on 11:26:12 (UT). We further obtained 60 images of 60 sec exposures in the R filter starting from September 22 on 10:01:34.4 (UT) and stopped on 11:27:50 (UT). We do not detect the optical afterglow both in the individual images and the stacked image at the XRT position (Goad et al., GCN Circ. 30850). The estimated five sigma upper limits of the combined image of the first observation (total exposure of 3540 sec) and the second observation (total exposure of 3600 sec) are 17.8 and 19.1 using the USNO-B1 catalog.

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[vsnet-grb-info 28784] IceCube-210926A: No neutrino counterpart candidates in ANTARES search
by GCN Circulars 27 Sep '21

27 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30887 SUBJECT: IceCube-210926A: No neutrino counterpart candidates in ANTARES search DATE: 21/09/27 08:32:10 GMT FROM: Antoine Kouchner at ANTARES Collaboration <kouchner(a)apc.in2p3.fr> Alexis Coleiro (APC/Universite de Paris) and Damien Dornic (CPPM/CNRS) on behalf of the ANTARES Collaboration. Using data from the ANTARES detector, we have performed a follow-up analysis of the recently reported cascade event IceCube-210926A (<https://gcn.gsfc.nasa.gov/notices_amon_icecube_cascade/135747_58376130.amon>). At the time of the alert, the reconstructed origin was -70.6 degrees below the horizon for ANTARES. No up-going muon neutrino candidate events were recorded within the 90% error box of the IceCube event during a +/- 1h time-window centered on the IceCube event time, and over which the potential source remained visible all time. This leads to a preliminary 90% confidence level upper limit on the muon-neutrino fluence from a point source of 21 GeV.cm^-2 over the energy range 2.3 TeV – 3.2 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and 30 GeV.cm^-2 (380 GeV - 240 TeV) for an E^-2.5 spectrum. A search over an extended time window of +/- 1 day has also yielded no detection (73% visibility). ANTARES <http://antares.in2p3.fr/> is the largest undersea neutrino detector (Mediterranean Sea) and it is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range. At 10 TeV, the median angular resolution for muon neutrinos is about 0.5 degrees. In the range 1-100 TeV ANTARES has a competitive sensitivity to this position in the sky.

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[vsnet-grb-info 28783] GRB 210926A: GECAM detection
by GCN Circulars 26 Sep '21

26 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30886 SUBJECT: GRB 210926A: GECAM detection DATE: 21/09/27 05:09:38 GMT FROM: Chao Zheng at IHEP <zhengchao97(a)ihep.ac.cn> C. Zheng, S. L. Xiong, X. Y. Zhao, Y. Huang, C. Cai, Z. W. Guo, C. Y. Li, S. Xiao, S. L. Xie, W. C. Xue, Q. B. Yi, Y. Zhao, Y. Q. Zhang, J. C. Liu, X. Y. Song, X. B. Li, P. Wang, J. Wang, Q. Luo, W. Chen, J. J. He, H. Wu, X. L. Zhang, C. W. Wang, P. Zhang, W. X. Peng, R. Qiao, D. Y. Guo, X. Ma, S. J. Zheng, G. Y. Zhao, Y. Q. Du, J. Liang, Z. 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 in-flight by a long burst, GRB 210926A, at 2021-09-26T20:52:28.250 UTC (denoted as T0). This burst consists of two episodes, with the first one triggered by Fermi/GBM (trigger ID: 654382283). Both episodes were triggered by GECAM-B with the on-ground pipeline. 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 multiple pulses with duration of about 90 s. The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB_210926A.png GECAM-B localized this burst to the following position (J2000): Ra: 351.51 deg Dec: -18.21 deg Err: 2.86 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 preliminary location could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/210926Aloc.png This location is consistent with Fermi/GBM position within the error. 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).

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[vsnet-grb-info 28782] GRB 210927A: Fermi GBM Final Real-time Localization
by GCN Circulars 26 Sep '21

26 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30885 SUBJECT: GRB 210927A: Fermi GBM Final Real-time Localization DATE: 21/09/27 00:54:10 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely SHORT GRB At 00:43:57 UT on 27 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210927A (trigger 654396242.858592 / 210927031). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 252.1, Dec = 0.0 (J2000 degrees, equivalent to J2000 16h 48m, 0d 00'), with a statistical uncertainty of 20.8 degrees. The angle from the Fermi LAT boresight is 28.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210927031/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210927031/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210927031/…

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[vsnet-grb-info 28781] GRB 210919A OSN 1.5m Source Confirmation
by GCN Circulars 26 Sep '21

26 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30884 SUBJECT: GRB 210919A OSN 1.5m Source Confirmation DATE: 21/09/26 23:01:27 GMT FROM: Alexander Kann at IAA-CSIC <kann(a)iaa.es> D. A. Kann (HETH/IAA-CSIC), A. Rossi (INAF-OAS), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), and F. Aceituno (IAA) report: We obtained observations of the enhance XRT position (Goad et al., GCN 30850) of the Swift short GRB 210919A (Tohuvavohu et al., GCN #30846) with the 1.5m telescope of OSN, Granada, Spain. We obtained 35 x 120 s images in the Rc band, starting at 03:28:22 UT on September 19, under good observing conditions. We obtained a second epoch, with 41 x 120 s images, the following night, starting at 2:59:51 UT on September 20. The source detected by Kann et al. (GCN #30883) is very faintly detected in the first epoch. Using the same comparison stars from the PanSTARRS catalog as used by Kann et al. (GCN #30883) (transformed to Rc via the Lupton equations, then transformed back to AB magnitudes), we measure: Rc = 24.47 +/- 0.53 mag @ 0.14944 d after trigger (AB mag). The source is undetected in the second epoch, but it is shallower, with Rc > 23.6 mag (AB) @ 1.13649 d after the GRB. We note this detection is also fainter than the upper limits listed in Kann et al. (GCN #30883).

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