//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25766 SUBJECT: Alert from the HAWC Burst Monitor HAWC-190917A DATE: 19/09/17 02:28:54 GMT FROM: Hugo Ayala at Pennsylvania State University The HAWC Collaboration (http://www.hawc-observatory.org/collaboration/) reports:On September 17, 2019, at 01:14:19 UT, HAWC detected a burst signal from its Burst Monitoring named HAWC-190917A. This monitor system looks for excesses above the expected background in time windows of 0.2, 1, 10 and 100 seconds. This event was found in the 1-second time window starting at the reported trigger time. The position of the alert is RA (J200): 321.84 deg Dec (J2000): 30.97 deg Location uncertainty (68% containment): 0.8 deg (statistical only). The monitor system found that this alert has a false alarm rate of 7.78 alert(s) per year. We strongly encourage follow-up observations of the HAWC alert region. The initial automated alert is recorded in here: https://gcn.gsfc.nasa.gov/notices_amon_hawc/18941_372.amon. HAWC is a very-high-energy gamma-ray observatory operating in Central Mexico at latitude 19 deg. north. Operating day and night with over 95% duty cycle, HAWC has an instantaneous field of view of 2 sr and surveys 2/3 of the sky every day. It is sensitive to gamma rays from 300 GeV to 100 TeV. [GCN OPS NOTE(22sep19): Per author's request, in the SUBJECT-line the "190916A" was changed to "190917A"; the date in the first sentence was changed from "September 16" to September 17", and the ID name was changed from "HAWC-190916A" to "HAWC-190917A".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25768 SUBJECT: Correction on the Trigger Date HAWC-190916A --> HAWC-190917A DATE: 19/09/17 03:10:18 GMT FROM: Hugo Ayala at Pennsylvania State University The HAWC Collaboration reported recently a HAWC Burst alert. The reported date has a mistake. The trigger time should be: September 17 2019, 01:14:19 UT First circular: https://gcn.gsfc.nasa.gov/gcn3/25766.gcn3 Hugo Ayala, In behalf of the HAWC collaboration. [GCN OPS NOTE(22sep19): "--> HAWC-190917A" was added to the SUBJECT-line.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25769 SUBJECT: HAWC-190916A: DDOTI Optical Observations DATE: 19/09/17 04:39:42 GMT FROM: Alan M Watson at UNAM Alan M. Watson (UNAM), Nat Butler (ASU), Eleonora Troja (GSFC/UMD), Rosa L. Becerra (UNAM), Simone Dichiara (GSFC/UMD), Diego Gonzalez (UNAM), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Margarita Pereyra (UNAM), and Tanner Wolfram (ASU) report: We observed the field of HAWC-190916A (Ayala, GCN Circ 25766, 25768) with the DDOTI wide-field imager at the Observatorio Astronomico Nacional on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) from 2019-09-17 03:14 to 2019-09-17 04:17 UTC (2.0 to 3.1 hours after the trigger). We obtained a total of 2340 seconds of exposure in the w filter. We calibrated our images against the APASS catalog. Our 10-sigma limiting magnitude is w = 19.5. Comparing our 10-sigma detections against the USNO-B1 catalog, we detect no reliable uncataloged sources with significant fading within 1.7 degrees of the nominal coordinates. We thank the staff of the Observatorio Astronomico Nacional in San Pedro Martir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25772 SUBJECT: HAWC-190916A: Upper limits from Fermi-GBM Observations DATE: 19/09/17 17:50:53 GMT FROM: Joshua Wood at MSFC/Fermi-GBM J. Wood (NASA/MSFC) reports on behalf of the Fermi GBM Team: For HAWC-190916A, Fermi-GBM was observing the full localization region at event time. There was no Fermi-GBM onboard trigger around the event time of HAWC-190916A (GCN 25766 and 25768). An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM also identified no counterpart candidates. The GBM targeted search, the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around trigger time, and also identified no counterpart candidates. We therefore set upper limits on impulsive gamma-ray emission. Using the representative soft, normal, and hard GRB-like templates described in arXiv:1612.02395, we set the following 3 sigma flux upper limits over 10-1000 keV (in units of 10^-7 erg/s/cm^2): Timescale Soft Normal Hard ------------------------------------ 0.128 s: 1.5 2.3 4.9 1.024 s: 0.6 0.9 1.9 8.192 s: 0.2 0.4 0.7 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25774 SUBJECT: HAWC-190916A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation DATE: 19/09/17 20:13:17 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group Antonio Martin-Carrillo (UCD), Francesca Onori V. Savchenko, C. Ferrigno (ISDC/UniGE, Switzerland) J. Rodi (IAPS-Roma, Italy) A. Coleiro (APC, France) S. Mereghetti (INAF IASF-Milano, Italy) on behalf of the INTEGRAL multi-messenger collaboration: https://www.astro.unige.ch/cdci/integral-multimessenger-collaboration Using INTEGRAL/SPI-ACS realtime data (following [1]) we have performed a search for a prompt gamma-ray counterpart of HAWC-190916A (GCN 25766, 25768). At the time of the event (2019-09-17 01:14:19 UTC, hereafter T0), INTEGRAL was operating in nominal mode. The peak of the event localization probability was at an angle of 114 deg with respect to the spacecraft pointing axis. This orientation implies strongly suppressed (5.8% of optimal) response of ISGRI, strongly suppressed (32% of optimal) response of IBIS/Veto, and somewhat suppressed (55% of optimal) response of SPI-ACS. The background within +/-300 seconds around the event was very stable (excess variance 1.2). We have performed a search for any impulsive events in INTEGRAL SPI- ACS (as described in [2]) data. We do not detect any significant counterparts and estimate a 3-sigma upper limit on the 75-2000 keV fluence of 3.3e-07 erg/cm^2 (within the 50% probability containment region of the source localization) for a burst lasting less than 1 s with a characteristic short GRB spectrum (an exponentially cut off power law with alpha=-0.5 and Ep=600 keV) occurring at any time in the interval within 300 s around T0. For a typical long GRB spectrum (Band function with alpha=-1, beta=-2.5, and Ep=300 keV), the derived peak flux upper limit is ~2.9e-07 (8.8e-08) erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range. We report for completeness and in order of FAP, all excesses identified in the search region. We find: 2 likely background excesses: scale | T | S/N | flux ( x 1e-06 erg/cm2/s) | FAP 0.65 | 80.8 | 4 | 0.52 +/- 0.134 +/- 0.189 | 0.417 0.75 | 184 | 4.2 | 0.523 +/- 0.124 +/- 0.191 | 0.646 Note that FAP estimates (especially at timescales above 2s) may be possibly further affected by enhanced non-stationary local background noise. This list excludes any excesses for which FAP is close to unity. All results quoted are preliminary. This circular is an official product of the INTEGRAL Multi-Messenger team. [1] Savchenko et al. 2017, A&A 603, A46 [2] Savchenko et al. 2012, A&A 541A, 122S //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25775 SUBJECT: HAWC-190916A: IceCube neutrino search DATE: 19/09/18 03:22:35 GMT FROM: Alex Pizzuto at ICECUBE/U of Wisconsin The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search for track-like muon neutrino events arriving from the position of HAWC-190916A (GCN 25766, 25768) in a time window 12 hours in duration centered on the burst time (2019-09-16 19:14:19.000 UTC to 2019-09-17 07:14:19.000 UTC). 1 track-like event is found in spatial coincidence with HAWC-190916A during this time period. This represents a p-value of 0.044 (1.7 sigma) with respect to an atmospheric background only hypothesis. Accordingly, this event would represent a time-integrated muon-neutrino flux normalization upper limit assuming an E^-2 spectrum (E^2 dN/dE) at the 90% CL of 5.2 x 10^-5 TeV cm^-2 for this observation period. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum are between approximately 1 TeV and 500 TeV. 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@icecube.wisc.edu. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25776 SUBJECT: HAWC-190916A: Upper limits from Insight-HXMT/HE observations DATE: 19/09/18 15:03:30 GMT FROM: Shuo Xiao at IHEP S. Xiao, Y. G. Zheng, C. Cai, Q. Luo, Q. B. Yi, Y. Huang, C. K. Li, G. Li, X. B. Li, J. Y. Liao, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team: Insight-HXMT was taking data normally around the trigger time (T0=2019-09-16T01:14:19 UTC) of HAWC-190916A event (GCN #25766), which was monitored without any occultation by the Earth. Within T0 +/- 100 s, no significant excess events (SNR > 3 sigma) are found in a search of the Insight-HXMT/HE raw light curves. Assuming the counterpart GRB with three typical GRB Band spectral models, two typical duration timescales (1 s, 10 s) from the center of the position of the alert is (RA=321.84 deg, DEC=30.97 deg), the 5-sigma upper-limits fluence (0.2 - 5 MeV, incident energy) are reported below: Band model 1 (alpha=-1.9, beta=-3.7, Ep=70 keV): 1 s: 3.1e-07 erg cm^-2 10 s: 1.2e-06 erg cm^-2 Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV): 1 s: 3.9e-07 erg cm^-2 10 s: 1.5e-06 erg cm^-2 Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV): 1 s: 3.0e-07 erg cm^-2 10 s: 1.4e-06 erg cm^-2 All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the spacecraft. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information could be found at: http://www.hxmt.org. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25779 SUBJECT: Correction on name for HAWC-190916A to HAWC-190917A DATE: 19/09/18 20:28:20 GMT FROM: Hugo Ayala at Pennsylvania State University Due to the reported correction on the trigger time of the HAWC Burst Alert to September 17 2019, 01:14:19 UT, the HAWC collaboration decided to change the name of the event to be in accordance with the UTC date. The name will be now HAWC-190917A. First circular: https://gcn.gsfc.nasa.gov/gcn3/25766.gcn3 Second circular: https://gcn.gsfc.nasa.gov/gcn3/25768.gcn3 Related circulars that followed-up the alert: https://gcn.gsfc.nasa.gov/gcn3/25769.gcn3 https://gcn.gsfc.nasa.gov/gcn3/25772.gcn3 https://gcn.gsfc.nasa.gov/gcn3/25774.gcn3 https://gcn.gsfc.nasa.gov/gcn3/25775.gcn3 https://gcn.gsfc.nasa.gov/gcn3/25776.gcn3 Hugo Ayala, On behalf of the HAWC Collaboration