//////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25283 SUBJECT: HAWC Alert 190806.56 Global MASTER-Net observations report DATE: 19/08/07 05:01:28 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias) D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the HAWC Alert 190806.56 (trigger No 957, 5h 13m 33.60s , + 6d 36m 36.00s, R=0.4) errorbox 47786 sec after trigger time at 2019-08-07 02:37:14 UT, with upper limit up to 18.3 mag. The observations began at zenit distance = 72 deg. The sun altitude is -35.5 deg. The galactic latitude b = -60 deg., longitude l = 98 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1098039 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 47877 | 2019-08-07 02:37:14 | MASTER-SAAO | ( 5h 13m 35.91s , + 6d 38m 30.89s) | C | 180 | 18.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [GCN PS NOTE(07aug19): Per author's request, the "IceCube" in the Subject-line and in the first sentence was changed to "HAWC".] //////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25284 SUBJECT: Alert from the HAWC Burst Monitor DATE: 19/08/07 21:14:38 GMT FROM: Hugo Ayala at Pennsylvania State University The HAWC Collaboration (http://www.hawc-observatory.org/collaboration/) reports: On August 6, 2019, at 13:20:48.00 UT, HAWC detected a burst signal from its GRB Monitoring. 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 100-second time window starting at the reported trigger time. The monitor system found that this alert has a false alarm rate of 0.83 event(s) per year. The position of the alert is (RA, Dec) = (78.125 deg, +6.589 deg) J2000 with a 90% containment radius of 0.4 deg (statistical only). The initial automated alert is recorded here: https://gcn.gsfc.nasa.gov/notices_amon_hawc/1008846_957.amon We strongly encourage follow-up observations of the HAWC alert region. 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. //////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25291 SUBJECT: HAWC Burst Alert 1008846_957: IceCube Neutrino Search DATE: 19/08/08 15:52:37 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 direction of HAWC Burst Alert 1008846_957 (GCN 25284) in a time window 12 hours in duration centered on the burst time (2019-08-06 07:20:48.0 UTC to 2019-08-06 19:20:48.0 UTC), during which IceCube was collecting good quality data. Zero track-like events are found in spatial coincidence with the location of the HAWC alert during this time period. Accordingly, the time-integrated muon-neutrino flux, multiplied by E^2, upper limit at the alert position assuming an E^-2 spectrum (E^2 dN/dE) at the 90% CL is 3.53 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 3 PeV. 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: 25306 SUBJECT: HAWC Burst Alert 1008846_957: Konus-Wind observations DATE: 19/08/09 14:26:22 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R.Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report: Konus-Wind (KW) was observing the whole sky at the time of the HAWC burst alert (2019-08-06 13:20:48.0 UTC, hereafter T0; The HAWC Collaboration GCN Circ. 25284). No triggered KW event happened in the +/- 1 day interval centered at T0. Using waiting-mode data (20-1500 keV) within the interval T0 +/- 2000 s, we have found a single 13 s-long event at ~30 minutes before T0 with a signal-to-noise ratio of ~4.5 sigma in the KW detector observing the HAWC event position. For the remaining part of the T0 +/- 2000 s interval we estimate an upper limit (90% conf.) on the 10 keV – 1.5 MeV fluence to 9.0x10^-7 erg/cm^2 for a burst lasting less than 2.944 s and having a typical KW short GRB spectrum (an exponentially cut off power law with alpha =-0.5 and Ep=500 keV). For a typical long GRB spectrum (the Band function with alpha=-1, beta=-2.5, and Ep=300 keV), the corresponding limiting peak flux is 2.2x10^-7 erg/cm^2/s (10 keV - 1.5 MeV, 2.944 s scale). All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25307 SUBJECT: HAWC-190806A: Swift-XRT observations DATE: 19/08/09 14:55:21 GMT FROM: Phil Evans at U of Leicester V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), B. Sbarufatti (PSU), D.N. Burrows (PSU), J. D. Gropp (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the HAWC-detected candidate GRB 19086A (GCN Circ. 25284) in a series of observations tiled on the sky. The total exposure time is 3.8 ks, distributed over 4 tiles; the maximum exposure at a single sky location was 2.6 ks. The data were collected between T0+25.6 ks and T0+32.8 ks, and are entirely in Photon Counting (PC) mode. Five uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Further observations are planned. Details of these sources are given below: Source 1: RA (J2000.0): 77.7590 = 05:11:2.16 Dec (J2000.0): +6.6677 = +06:40:03.6 Error: 8.5 arcsec (radius, 90% conf.) Count-rate: (9.6 [+5.2, -3.9])e-3 ct s^-1 Distance: 1339 arcsec from HAWC position. Source 2: RA (J2000.0): 78.0710 = 05:12:17.03 Dec (J2000.0): +6.4737 = +06:28:25.2 Error: 5.6 arcsec (radius, 90% conf.) Count-rate: 0.0102 [+0.0033, -0.0028] ct s^-1 Distance: 457 arcsec from HAWC position. Flux: (2.31 [+0.75, -0.62])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 3: RA (J2000.0): 78.0613 = 05:12:14.72 Dec (J2000.0): +6.2531 = +06:15:11.3 Error: 10.6 arcsec (radius, 90% conf.) Count-rate: (6.6 [+4.1, -2.9])e-3 ct s^-1 Distance: 1230 arcsec from HAWC position. Source 4: RA (J2000.0): 78.0233 = 05:12:5.59 Dec (J2000.0): +6.7577 = +06:45:27.9 Error: 12.7 arcsec (radius, 90% conf.) Count-rate: (3.9 [+2.2, -1.6])e-3 ct s^-1 Distance: 708 arcsec from HAWC position. Source 5: RA (J2000.0): 77.8911 = 05:11:33.86 Dec (J2000.0): +6.7469 = +06:44:48.9 Error: 6.1 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: 0.0102 [+0.0049, -0.0038] ct s^-1 Distance: 1011 arcsec from HAWC position. Flux: (3.7 [+1.8, -1.4])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00084. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25308 SUBJECT: HAWC-190806A: Upper limits from Fermi-GBM Observations DATE: 19/08/09 20:14:57 GMT FROM: Joshua Wood at MSFC/Fermi-GBM J. Wood (NASA/MSFC) and S. Poolakkil (UAH) report on behalf of the Fermi GBM Team: For HAWC-190806A, Fermi-GBM was observing the full localization region at event time. There was no Fermi-GBM onboard trigger around the event time of HAWC-190806A (GCN 25284). 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: 2.4 4.8 14. 1.024 s: 0.9 1.5 4.6 8.192 s: 0.4 0.7 1.7 //////////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 25309 SUBJECT: HAWC-190806A: upper limits from INTEGRAL SPI-ACS and IBIS prompt observation DATE: 19/08/09 22:44:12 GMT FROM: Volodymyr Savchenko at ISDC,U of Geneve 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, and following [1], we have performed a search for prompt gamma-ray counterparts of HAWC-190806A (GCN 25284). At the time of the event (2019-08-06 13:20:48 UTC, hereafter T0), INTEGRAL was operating in nominal mode. The event localization was at an angle of 33 deg with respect to thespacecraft pointing axis. This orientation implies a strongly suppressed(17% of optimal) response of ISGRI, a strongly suppressed (31% ofoptimal) response of IBIS/Veto, and a near-optimal (75% of optimal)response of SPI-ACS. This orientation implies a favorableresponse of IBIS/PICsIT. Thebackground within +/-300 seconds around  the event was ratherstable (excess variance 1.3, slightly higher than usual). We have performed a search for any impulsive events in INTEGRAL SPI-ACS (as described in [2]) data. We detect a marginal event (S/N 3.3) at a 3.5s time scale atT0-1.8s. The peak count rate of the signal in SPI-ACS is 713 cts/s, which corresponds to a flux between 1.2e-07 and 1.7e-07 erg/cm2/s, depending on thelocation within the source localization region, and assuming a typical short GRB spectrum (an exponentially cut offpower law with alpha=-0.5 and Ep=600 keV). This estimate does not take into account the uncertaintyrelated to the unknown event spectrum, the 20% systematic uncertainty on theresponse, or any dead-time correction. We derive preliminary estimate of the association FAP at the level of 0.011 (2.3 sigma). This tentatively indicates a random association. Further analysis, taking into account accurate FAR measured on the basis of the study ofthe background during days surrounding the event might be reported in aforthcoming circulars. In the IBIS/PICsIT analysis, we do not detect any relevant signal, despite an orientation favorable for this instrument. This disfavours a cosmic origin of the observed SPI-ACS excess. Otherwise, we estimate a 3-sigma upper limit on the 75-2000 keV fluence of 2e-07 erg/cm^2 for a burst lasting less than 1 s with a characteristic short GRB spectrum  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 ~1.7e-07 (6.9e-08) erg/cm^2/s at 1 s (8 s) time scale in 75-2000 keV energy range. In addition, we identify the following low-S/N excesses, which likely belong to thebackground: scale | T     | S/N | flux ( x 1e-7 erg/cm2/s) | FAP 2.9   | -135  | 3.8 | 1.9 ± 0.5 ± 0.8          | 0.2 2.7   | -238  | 4.2 | 2.1 ± 0.5 ± 0.8          | 0.231 0.1   | -9.26 | 4.2 | 10.6 ± 2.7 ± 4.4         | 0.248 0.8   | 92.7  | 4.1 | 3.6 ± 0.9 ± 1.5          | 0.341 0.5   | -113  | 3.9 | 4.5 ± 1.2 ± 1.8          | 0.786 1.1   | -275  | 3.9 | 3.0 ± 0.8 ± 1.2          | 0.896 Note that FAP estimates (especially at timescales above 2s) may be further affected by possibly 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: 25315 SUBJECT: HAWC-190806A: Upper limits from Insight-HXMT/HE observations DATE: 19/08/13 00:53:58 GMT FROM: YaoGuang Zheng at IHEP Y. G. Zheng, C. Cai, Q. Luo, S. Xiao, 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=2019-08-06T13:20:48.00 UTC) of HAWC-190806A event (GCN #25284), 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=78.125 deg, DEC=6.589 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: 1.8e-08 erg cm^-2 10 s: 1.8e-07 erg cm^-2 Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV): 1 s: 3.6e-08 erg cm^-2 10 s: 3.3e-07 erg cm^-2 Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV): 1 s: 1.8e-07 erg cm^-2 10 s: 1.2e-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.