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

[vsnet-grb-info 28760] GRB 210919A: Swift-BAT refined analysis
by GCN Circulars 22 Sep '21

22 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30863 SUBJECT: GRB 210919A: Swift-BAT refined analysis DATE: 21/09/22 22:04:47 GMT FROM: Sibasish Laha at GSFC <sibasish.laha(a)nasa.gov> S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tempa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210919A (trigger #1073893) (Tohuvavohu et al., GCN Circ. 30846). The BAT ground-calculated position is RA, Dec = 80.242, 1.286 deg which is RA(J2000) = 05h 20m 58.1s Dec(J2000) = +01d 17' 08.8" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 50%. The BAT light curve showed a short pulse of a duration ~ 1 sec. T90 (15-350 keV) is 0.16 +- 0.03 sec (estimated error including systematics). The time-averaged spectrum from T+0.05 to T+0.24 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.58 +- 0.27. The fluence in the 15-150 keV band is 8.8 +- 1.7 x 10^-08 erg/cm2. The 1-sec peak photon flux measured from T-0.35 sec in the 15-150 keV band is 1.5 +- 0.3 ph/cm2/sec. 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/1073893/BA/

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[vsnet-grb-info 28759] IceCube-210922A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 22 Sep '21

22 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30862 SUBJECT: IceCube-210922A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 21/09/22 19:45:10 GMT FROM: Dr. Massimiliano Lincetto at Ruhr-Universitaet Bochum <lincetto(a)astro.rub.de> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 2021-09-22 at 18:17:20.948 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_GOLD alert stream. The average astrophysical neutrino purity for Gold alerts is 50%. This alert has an estimated false alarm rate of 0.1472 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/135736_30987826.amon) more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 2021-09-22 Time: 18:17:20.948 RA: 60.73 (+0.96/-0.66 deg 90% PSF containment) J2000 Dec: -4.18 (+0.42/-0.55 deg 90% PSF containment) J2000 We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. There are no Fermi 4FGL or 3FHL catalog sources in the 90% uncertainty region. The nearest gamma-ray source in either catalog is 4FGL J0357.2-0319 / 3FHL J0357.3-0316 at RA: 59.32 deg, Dec: -3.32 deg (1.64 deg away from the best-fit event position). The source is classified as having a possible blazar origin. This neutrino candidate event has an estimated neutrino energy of ~750 TeV and an estimated signalness of >90%, making it one of the most interesting neutrino alerts issued in the last year. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu

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[vsnet-grb-info 28758] GRB 210912A: LBT optical observations
by GCN Circulars 22 Sep '21

22 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30861 SUBJECT: GRB 210912A: LBT optical observations DATE: 21/09/22 11:41:40 GMT FROM: Andrea Melandri at INAF-OAB <andrea.melandri(a)inaf.it> A. Rossi (INAF-OAS Bologna) report on behalf of the CIBO collaboration: We observed the field of GRB 210912A (Troja et al., GCN 30820) in the r' band with the LBC imager mounted on LBT (Mt Graham, AZ, USA). We obtained 10min of imaging at the midtime 11:20 UT on 2021-09-17 (~5 days after the burst trigger). We clearly detect the optical afterglow (Hu et al., GCN 30823; Pankov et al., GCN 30825; Kuin & Troja, GCN 30832; Kann et al. GCN 30834; Nicuesa Guelbenzu et al. GCN 30837) with the following preliminary AB magnitude: r = 22.73 +- 0.05 calibrated against Pan-STARRS field stars. It is likely that this flux is significantly affected by host galaxy contamination (Kann et al. GCN 30829). We acknowledge the excellent support from the LBTO and LBT-INAF staff, particularly A. Cardwell, J. Williams and D. Paris, in obtaining these observations.

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[vsnet-grb-info 28757] GRB 210919A: Lowell Discovery Telescope upper limits (correction to GCN 30859)
by GCN Circulars 21 Sep '21

21 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30860 SUBJECT: GRB 210919A: Lowell Discovery Telescope upper limits (correction to GCN 30859) DATE: 21/09/21 19:15:27 GMT FROM: Amy Gottlieb at UMD <Agottlieb7(a)gmail.com> This is the corrected version of GCN 30859 submitted as plain text instead of html. A.Gottlieb (UMD, NASA-GSFC), S.Dichiara (UMD, NASA-GSFC), S.B. Cenko (NASA-GSFC), E. Troja (UMD, NASA-GSFC), J.M. Durbak (UMD), A. Kutyrev (UMD, NASA-GSFC), S. Veilleux (UMD), report on behalf of a larger collaboration: We observed the field of the short GRB 210919A (Tohuvavohu et al., GCN Circ. 30846) using the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery Telescope (LDT) at Happy Jack, AZ. Observations started on September 21, 11:27:43 UT (2.46 days after the Swift trigger) taking 5 exposures of 200 s each with SDSS r filter. Observations were taken at an airmass of about 1.27 and seeing of about 1.5". We do not find any source inside the enhanced XRT position (Goad et al., GCN Circ. 30850) down to a 3-sigma limiting magnitude of r>23.6 AB mag. Magnitudes are calibrated against the SDSS catalog and not corrected for Galactic extinction. We thank the staff of the Lowell Discovery Telescope for assistance with these observations.

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[vsnet-grb-info 28756] GRB 210919a: Lowell Discovery Telescope upper limits
by GCN Circulars 21 Sep '21

21 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30859 SUBJECT: GRB 210919a: Lowell Discovery Telescope upper limits DATE: 21/09/21 15:25:55 GMT FROM: Amy Gottlieb at UMD <Agottlieb7(a)gmail.com> <html xmlns:o=3D"urn:schemas-microsoft-com:office:office" xmlns:w=3D"urn:sc= hemas-microsoft-com:office:word" xmlns:m=3D"http://schemas.microsoft.com/of= fice/2004/12/omml" xmlns=3D"http://www.w3.org/TR/REC-html40"><head><meta ht= tp-equiv=3DContent-Type content=3D"text/html; charset=3Dutf-8"><meta name= =3DGenerator content=3D"Microsoft Word 15 (filtered medium)"><style></style></head><body lang=3DEN-US style=3D'word-wrap:break-word'><div cl= ass=3DWordSection1>A.Gottlieb (UMD, NASA-GSFC), S.Dich= iara (UMD, NASA-GSFC),  S.B. Cenko<o:p></o:p>= (NASA-GSFC), E. Troja (UMD, NASA-GSFC), J.M. Durbak (UMD), A. Kutyrev <o:p>= </o:p>(UMD, NASA-GSFC), S. Veilleux (UMD), report = on behalf of a larger <o:p></o:p>collaboration:<o:= p></o:p> <o:p></o:p>= We observed the field of the short GRB 210919A (Tohuvavohu et al., <o:p></o= :p>GCN Circ. 30846) using the Large Monolithic Ima= ger (LMI) on the 4.3m <o:p></o:p>Lowell Discovery = Telescope (LDT) at Happy Jack, AZ. Observations <o:p></o:p>started on September 21, 11:27:43 UT (2.46 days after the Swift <o= :p></o:p>trigger) taking 5 exposures of 200 s each= with SDSS r filter. <o:p></o:p>Observations were = taken at an airmass of about 1.27 and seeing of <o:p></o:p>about 1.5". We do not find any source inside the enhanced <o:= p></o:p>XRT position (Goad et al., GCN Circ. 30850= ) down to a 3-sigma <o:p></o:p>limiting magnitude = of r>23.6 AB mag.<o:p></o:p>Magnitudes are cali= brated against the SDSS catalog and not <o:p></o:p>corrected for Galactic extinction.<o:p></o:p>&nbs= p;<o:p></o:p>We thank the staff of the Lowell Disc= overy Telescope for assistance <o:p></o:p>with the= se observations.<o:p></o:p> <o:p></o:p><p= class=3DMsoNormal><o:p> </o:p></div></body></html>

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[vsnet-grb-info 28755] GRB210919A: Keck NIRC2 Kp band upper limits
by GCN Circulars 21 Sep '21

21 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30858 SUBJECT: GRB210919A: Keck NIRC2 Kp band upper limits DATE: 21/09/21 06:58:23 GMT FROM: Jielai Zhang at Swinburne U. of Tech. <jielaizhangscience(a)gmail.com> GRB210919A: Keck NIRC2 Kp band upper limits Jielai Zhang (Swinburne University of Technology, Swinburne), Jeff Cooke (Swinburne), Gabriela Canalizo (University of California Riverside), Sara Marlene Doan (George Mason University), Shobita Satyapal (George Mason University), Thomas Bohn (University of California Riverside), Jeffrey Mckaig (George Mason University) We carried out follow-up observations of GRB210919A (A. Tohuvanohu et al. GCNC #30846) with Keck II, using the NIRC2 instrument with the wide camera. Observations began on September 19 at 13:48:32.649 UT , ~13.3 hours after the GRB trigger. We took 6 X 107s exposures using the Kp filter. No GRB IR counterpart was found in the NIRC2 data within the XRT error area (M. R. Goad et al. GCNC #30850). No GRB IR counterpart was found in the NIRC2 data within the XRT error area (M. R. Goad et al. GCNC #30850) to an upper limit of Kp > 21.5 mag (AB, with no Galactic extinction correction).

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[vsnet-grb-info 28754] GRB 210919A: Swift/UVOT Upper Limits
by GCN Circulars 20 Sep '21

20 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30857 SUBJECT: GRB 210919A: Swift/UVOT Upper Limits DATE: 21/09/21 02:35:14 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) and A. Tohuvavohu (U. Toronto) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210919A 100 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 30846). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 30850) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 100 249 147 >20.8 u_FC 312 561 246 >19.9 white 100 1193 343 >21.4 v 643 1244 70 >18.7 b 568 1342 63 >19.3 u 312 1318 304 >19.8 w1 693 1293 58 >19.7 m2 1248 1268 19 >19.0 w2 618 1044 39 >19.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.141 in the direction of the burst (Schlegel et al. 1998).

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[vsnet-grb-info 28753] GRB 210919A: LOAO and LSGT optical upper limits
by GCN Circulars 20 Sep '21

20 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30856 SUBJECT: GRB 210919A: LOAO and LSGT optical upper limits DATE: 21/09/20 08:00:38 GMT FROM: Sophia Kim at Seoul National U. <sophiak(a)astro.snu.ac.kr> GRB 210919A: LOAO and LSGT optical upper limits Sophia Kim (Seoul National University, SNU), Myungshin Im (SNU); Jeff Cooke (Swinburne University of Technology), Gu Lim (SNU); report on behalf of IMSNG & GECKO Collaboration We carried out follow-up observations of GRB210919A (A. Tohuvanohu et al. GCNC #30846) with the 1-m telescope at Mt. Lemon Optical Astronomy Observatory (LOAO) in US Arizona. Observations began on September 19 at 10:42:02 UT , ~10.23 hours after the GRB trigger. We took 19 X 180s exposures in Johnson R-band. We also observed the same field with the 0.43-meter (17 inch) Lee Sang Gak Telescope (LSGT) located at the Siding Spring Observatory (SSO) in Australia. Imaging began on the same day at 16:12:53 UT, ~15.73 hours after the GRB trigger. The observations were performed in a Sloan r-, i- and z-band sequences with 11 X 300s exposures in each band. No GRB optical counterpart was found in the LOAO and LSGT data within the XRT error area (M. R. Goad et al. GCNC #30850). This result is consistent with the optical observational results by other teams (V. Lipunov et al. GCNC #30847, Y.-D. Hu et al. GCNC #30848, R. Strausbaugh et al. GCNC #30849, M.R. Goad et al. GCNC #30850, N. Pankov et al. GCNC #30851, D. A. Perley et al. GCNC #30852, M. Perri et al. GCNC #30854 and Y.Takamatsu et al. GCNC #30855). The following is our observation results. We calibrated flux with the PS1 catalog and used AB magnitude system. (The magnitudes are not corrected for extinction.) #-------------------------------------------------------------------------------------------------------------- OBS/TEL DATE-OBS(UT) FILTER EXPT UL(3σ)[ABmag] UL(5σ)[ABmag] LOAO/1-m 2021-09-19T10:42:02 R 3420s >21.716 >21.162 SSO/LSGT 2021-09-19T16:12:53 r 3300s >20.160 >19.605 SSO/LSGT 2021-09-19T16:18:17 i 3300s >19.107 >18.553 SSO/LSGT 2021-09-19T16:23:53 z 3300s >18.674 >18.119 -------------------------------------------------------------------- Sophia Kim Graduate Course, Astronomy Program, Dept. of Physics & Astronomy, Seoul National University 56-1 San, Shillim-dong, Kwanak-gu, Seoul, KOREA mobile: *+82-10-2668-3783* e-mail : *sophiak(a)astro.snu.ac.kr <sophiak(a)astro.snu.ac.kr>*

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[vsnet-grb-info 28752] GRB 210919A: MITSuME Akeno optical upper limits
by GCN Circulars 19 Sep '21

19 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30855 SUBJECT: GRB 210919A: MITSuME Akeno optical upper limits DATE: 21/09/20 00:36:51 GMT FROM: Yutaka Takamatsu at Tokyotech <takamatsu(a)hp.phys.titech.ac.jp> Y. Takamatsu, R. Hosokawa, K. L. Murata, N. Ito, Y. Imai, M. Niwano, R. Noto, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration: We observed the field of GRB 210919A (A. Tohuvavohu et al. GCN Circular #30846, V. Lipunov et al. GCN Circular #30847, Y.-D. Hu et al. GCN Circular #30848, R. Strausbaugh et al. GCN Circular #30849, M.R. Goad et al. GCN Circular #30850, N. Pankov et al. GCN Circular #30851, D. A. Perley et al. GCN Circular #30852, M. Perri et al. GCN Circular #30854) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope Akeno. The observation with a series of 60 sec exposures started at 2021-09-19 15:22:32 UT (14.9 hours after Swift trigger). We stacked the images with good conditions. We did not detect any uncatalogued sources within the XRT error region (M.R. Goad et al. GCN Circular #30850). We obtained the 5-sigma limits of the stacked images as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits ------------------------------------------------------------------------------------------------ 17.3 2021-09-19 17:48:08.43 11160 g'>19.2, Rc>20.5, Ic>19.6 ------------------------------------------------------------------------------------------------ T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used PS1 catalog for flux calibration. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire)

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[vsnet-grb-info 28751] GRB 210919A: Swift-XRT refined Analysis
by GCN Circulars 19 Sep '21

19 Sep '21

TITLE: GCN CIRCULAR NUMBER: 30854 SUBJECT: GRB 210919A: Swift-XRT refined Analysis DATE: 21/09/19 15:57:30 GMT FROM: Phil Evans at U of Leicester <pae9(a)leicester.ac.uk> M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), J. D. Gropp (PSU), J.A. Kennea (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and A. Tohuvavohu report on behalf of the Swift-XRT team: We have analysed 1.5 ks of XRT data for GRB 210919A (Tohuvavohu et al. GCN Circ. 30846), from 105 s to 1.6 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 30850). We cannot determine at the present time whether the source is fading. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01073893. This circular is an official product of the Swift-XRT team.

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