//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28783 SUBJECT: Swift GRB201026.94: Global MASTER-Net observations report DATE: 20/10/26 22:55:24 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, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), 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-IAC robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Spain (IAC Teide Observatory) was pointed to the Swift GRB201026.94 (trigger No 1002103,13h 06m 39.36s , +83d 45m 39.6s, R=0.05) errorbox 665 sec after trigger time at 2020-10-26 22:48:39 UT, with upper limit up to 16.9 mag. The observations began at zenith distance = 68 deg. The sun altitude is -58.5 deg. The galactic latitude b = 34 deg., longitude l = 122 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1469722 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 731 | MASTER-IAC | C | 130 | 16.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28784 SUBJECT: GRB 201026A: Swift detection of a burst DATE: 20/10/26 22:56:15 GMT FROM: David Palmer at LANL S. B. Cenko (GSFC), S. D. Barthelmy (GSFC), M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), S. Laha (GSFC/UMBC/CRESST), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), M. J. Moss (GWU), D. M. Palmer (LANL) and T. Sbarrato (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 22:37:34 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 201026A (trigger=1002103). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 196.664, +83.761 which is RA(J2000) = 13h 06m 39s Dec(J2000) = +83d 45' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex peak structure with a duration of about 30 sec. The peak count rate was ~1700counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 22:38:53.0 UT, 78.8 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 196.7408, 83.7849 which is equivalent to: RA(J2000) = 13h 06m 57.79s Dec(J2000) = +83d 47' 05.6" with an uncertainty of 4.8 arcseconds (radius, 90% containment). This location is 91 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 7.01e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 87 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 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.18. Burst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28785 SUBJECT: GRB 201026A: NOT optical upper limits DATE: 20/10/27 00:31:29 GMT FROM: Daniele B Malesani at DTU Space L. Izzo (DARK/NBI), D. B. Malesani (DTU Space), T. Kuutma (NOT), report on behalf od a larger collaboration: We observed the optical afterglow of GRB 201026A (Cenko et al., GCN 28784) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC imaging camera. A set of 2x300 s and 5x200 s images was secured in the SDSS r and z bands, respectively. The mid time of the observation was Oct 26.968 (36.2 min after the GRB). Observations were conducted at high airmass under moderate seeing conditions (1.4"). No new object is detected consistent with the XRT position, down to a limiting magnitude r= 21.5, z = 21.4 AB (3 sigma), calibrated against nearby stars from the Pan-STARRS catalog. We note the presence of a faint, possibly extended object visible in the archival Pan-STARRS images, at a position consistent (RA = 13:06:58.71, Dec = +83:46:58.5) with that of the X-ray afterglow. This object could be the host galaxy of GRB 201026A, but we caution that the currently available uncertainty radius of the XRT position is still relatively large (3.9"), hence the association not robust. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28786 SUBJECT: GRB 201026A: NanShan/NEXT-0.6m optical upper limit DATE: 20/10/27 01:11:02 GMT FROM: Dong Xu at NAOC/CAS Z.P. Zhu (NAOC, HUST), S.Y. Fu, X. Liu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report: We observed the field of GRB 201026A (Cenko et al., GCN 28784) using the NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. Observations automatically started at 22:49:35 UT on 2020-10-26, i.e., 12 min after the BAT trigger. We obtained 3x40 s, 4x60 s and 12x90 s frames in the Sloan r-filter. No new optical source is detected in our stacked image at the XRT position, down to a limiting magnitude of r = 20.5, calibrated with the nearby Pan-STARRS field. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28790 SUBJECT: GRB 201026A: FRAM-ORM optical detection limit DATE: 20/10/27 08:33:15 GMT FROM: Martin Jelinek at Astro.Inst-AVCR,Ondrejov Martin Jelinek and Jan Strobl (ASU CAS Ondrejov, CZ), Sergey Karpov, Martin Masek, Petr Janecek, Jakub Jurysek, Jan Ebr, Ronan Cunniffe, Petr Travnicek and Michael Prouza (Institute of Physics, Prague, CZ) report: The 25cm robotic telescope FRAM-ORM at La Palma (Spain) reacted robotically to the alert of GRB201026A (Cenko et al GCNC 28784), obtaining a series of 20 s unfiltered images starting at 22:50:58.9 UT, i.e. 13.4 min post trigger. We do not detect any new source within or near the XRT errorbox neither in single images (3-sigma limit R>~17.1, (Vega), calibrated by the Atlas catalog) nor in a combined 15x20s frame (mean exp time 21.15 min post trigger, 3-sigma limit R>~18.5) similarly to Lipunov et al. (GCNC 28783), Izzo et al. (GCNC 28785) and Zhu et al. (GCNC 28786) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28791 SUBJECT: GRB 201026A: Enhanced Swift-XRT position DATE: 20/10/27 09:21:54 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 466 s of XRT Photon Counting mode data and 1 UVOT images for GRB 201026A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 196.74662, +83.78196 which is equivalent to: RA (J2000): 13h 06m 59.19s Dec (J2000): +83d 46' 55.0" with an uncertainty of 1.9 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28793 SUBJECT: GRB 201026A: Swift/UVOT Upper Limits DATE: 20/10/27 14:17:32 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (UCL-MSSL) and S. B. Cenko (GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 201026A 88 s after the BAT trigger (Cenko et al., GCN Circ. 28784). No optical afterglow consistent with the XRT position (Goad et al., GCN Circ. 28791) 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 88 238 147 >20.6 white 88 904 210 >20.9 u_FC 300 550 246 >20.1 v 630 823 39 >18.3 b 563 749 32 >19.2 u 300 724 265 >20.2 w1 680 873 39 >18.5 w2 4139 4518 197 >19.3 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.18 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28796 SUBJECT: GRB 201026A: Swift-XRT refined Analysis DATE: 20/10/27 22:56:03 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (ASDC), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), K.L. Page (U. Leicester) and S.B. Cenko report on behalf of the Swift-XRT team: We have analysed 3.2 ks of XRT data for GRB 201026A (Cenko et al. GCN Circ. 28784), from 85 s to 46.3 ks after the BAT trigger. The data comprise 361 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 28791). The light curve can be modelled with a power-law decay with a decay index of alpha=0.90 (+1.12, -0.13). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.82 (+/-0.03). The best-fitting absorption column is 4.84 (+0.22, -0.21) x 10^21 cm^-2, in excess of the Galactic value of 1.1 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.4 x 10^-11 (6.4 x 10^-11) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 4.84 (+0.22, -0.21) x 10^21 cm^-2 Galactic foreground: 1.1 x 10^21 cm^-2 Excess significance: 29.0 sigma Photon index: 1.82 (+/-0.03) If the light curve continues to decay with a power-law decay index of 0.90, the count rate at T+24 hours will be 5.6 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.5 x 10^-13 (3.6 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01002103. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28797 SUBJECT: GRB 201026A: Fermi GBM detection DATE: 20/10/28 00:03:33 GMT FROM: Rachel Hamburg at UAH R. Hamburg (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 22:37:33.06 UT on 26 October 2020, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 201026A (trigger 625444658 / 201026943), which was initially misclassified as a distant particle event by the GBM flight software. GRB 201026A was also detected by the Swift/BAT and the Swift/XRT (Cenko et al. 2020, GCN 28784). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 58 degrees. The GBM light curve shows a main pulse with a duration (T90) of about 35 s (50-300 keV). There is also later emission extending to approximately T0+280 s. We cannot conclusively confirm it is related to the main emission episode with GBM data alone; however, similar late-time emission can be seen in the Swift-XRT lightcurve (Evans et al. 2020, GCN 28796). The time-averaged spectrum of the main pulse from T0-16 s to T0+23 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.83 +/- 0.10 and the cutoff energy, parameterized as Epeak, is 68 +/- 3 keV. A Band function fits the spectrum equally well with Epeak = 63 +/- 5 keV, alpha = -0.73 +/- 0.14 and beta = -2.84 +/- 0.34. The event fluence (10-1000 keV) in this time interval is (3.96 +/- 0.14)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1.47 s in the 10-1000 keV band is 3.04 +/- 0.22 ph/s/cm^2. For the later emission episode, the time-averaged spectrum from T0+188 s to T0+237 s is best fit by a simple power law function with index -1.84 +/- 0.04. The event fluence (10-1000 keV) in this time interval is (4.51 +/- 0.29)E-06 erg/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html 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: 28800 SUBJECT: GRB 201026A: Swift-BAT refined analysis DATE: 20/10/29 01:11:22 GMT FROM: Sibasish Laha at GSFC GRB 201026A: Swift-BAT refined analysis S. D. Barthelmy (GSFC), S. B. Cenko (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), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-60 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 201026A (trigger #1002103) (S. B. Cenko et al., GCN Circ. 28784). The BAT ground-calculated position is RA, Dec = 196.696, 83.807 deg which is RA(J2000) = 13h 06m 47.0s Dec(J2000) = +83d 48' 24.3" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 46%. The BAT light curve showed a complex structure. There are two prominent peaks, at ~ T+0 sec and T+210 sec with a duration of about 50 sec and 60 sec respectively. There is a small peak at T+140 to T+170 sec, and possibly a precursor at T-60 to T-40 sec. T90 (15-350 keV) is 135.38 +- 120.84 sec (estimated error including systematics). The time-averaged spectrum from T-13 to T+146 sec and T+165 to T+230 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.94 +- 0.09. The fluence in the 15-150 keV band is 5.6 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+1.05 sec in the 15-150 keV band is 2.2 +- 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/1002103/BA/