//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22850 SUBJECT: GRB 180626A: Swift detection of a burst with an optical counterpart DATE: 18/06/26 08:34:26 GMT FROM: Kim Page at U.of Leicester P. A. Evans (U Leicester), A. P. Beardmore (U Leicester), J.D. Gropp (PSU), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC) and K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift Observatory Team: At 08:21:16 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180626A (trigger=844615). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 243.567, +14.764 which is RA(J2000) = 16h 14m 16s Dec(J2000) = +14d 45' 52" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 50 sec. The peak count rate was ~3400 counts/sec (15-350 keV), at ~-2 sec after the trigger. The XRT began observing the field at 08:23:16.9 UT, 120.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 243.57544, 14.75598 which is equivalent to: RA(J2000) = 16h 14m 18.11s Dec(J2000) = +14d 45' 21.5" with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 41 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (3.47 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.2 (+2.28/-2.05) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 123 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 16:14:18.12 = 243.57551 DEC(J2000) = +14:45:25.5 = 14.75707 with a 90%-confidence error radius of about 0.81 arc sec. This position is 5.1 arc sec. from the center of the XRT error circle. The estimated magnitude is 20.71 with a 1-sigma error of about 0.23. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04. Burst Advocate for this burst is P. A. Evans (pae9 AT star.le.ac.uk). 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/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22851 SUBJECT: GRB 180626A: A long GRB detected by INTEGRAL DATE: 18/06/26 09:34:14 GMT FROM: Diego Gotz at CEA D.Gotz (CEA, Saclay), S.Mereghetti (IASF-Milano), C.Ferrigno, E. Bozzo, V.Savchenko (ISDC, Versoix), L. Ducci (IAAT/ISDC) and J.Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report: a gamma ray burst lasting about 40 s has been detected by IBAS in the IBIS/ISGRI data at 08:21:04 UT of June 26, 2018 The refined coordinates (J2000) are: R.A.= 243.5715 deg DEC.= 14.7486 deg with an uncertainty of 1.1 arcmin (90% c.l.). The burst had a measured peak flux of about 2.7 counts/cm2/s (20-200 keV, 1-s integration time) and a fluence in the same energy range of about 2e-6 erg/cm2. We note that both those values are lower limits, due to telemetry saturation at satellite level. This burst was also detected by the Swift/BAT, XRT and UVOT (Evans et al., GCN 22850), and the IBIS position is at 33 arc seconds from the UVOT one. A plot of the light curve will be posted at http://ibas.iasf-milano.inaf.it/IBAS_Results.html //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22852 SUBJECT: GRB 180626A: Enhanced Swift-XRT position DATE: 18/06/26 10:07:10 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 804 s of XRT Photon Counting mode data and 1 UVOT images for GRB 180626A, 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 = 243.57603, +14.75692 which is equivalent to: RA (J2000): 16h 14m 18.25s Dec (J2000): +14d 45' 24.9" with an uncertainty of 1.8 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: 22853 SUBJECT: GRB 180626A: ISON-MN optical observations DATE: 18/06/26 11:25:47 GMT FROM: Alexei Pozanenko at IKI, Moscow L. Elenin (KIAM), E. Mazaeva (IKI), A. Pozanenko (IKI), A. Volnova (IKI), I. Molotov (KIAM) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 180626A (Evans et al., GCN 22850) with ISON-NM observatory. Observation started 51 s after burst trigger. We do not find optical afterglow (Evans et al., GCN 22850) in a combined image of first 5 frames. Preliminary photometry of the filed is following. Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) 2018-06-26 08:22:07 0.00146 CR 5* 20 n/d n/d 17.3 The photometry is based on several nearby USNO-B1.0 stars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22854 SUBJECT: GRB 180626A: LCO Haleakala observations DATE: 18/06/26 12:13:43 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy R. Martone, C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), A. Cucchiara (U. of Virgin Islands) on behalf of a large collaboration report: The LCO 2-m unit at Haleakala Observatory (Hawaii), former FTN, began observing Swift and INTEGRAL GRB 180626A (Evans et al. GCN 22850; Gotz et al. GCN 22851) on June 26, 08:41:11 UT (20 min after the GRB trigger time) with the SDSS ri filters. The optical counterpart (Evans et al.) is clearly detected  with the following magnitudes: Mid Time since GRB    Exposure         Filter        Magnitude (hrs)                  (s) ------------------------------------------------------------------ 0.424                 5x120            SDSS-R        20.96 +- 0.12 0.617                 5x120            SDSS-I        20.53 +- 0.12 ------------------------------------------------------------------ as calibrated against nearby SDSS objects. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22855 SUBJECT: GRB 180626A: RATIR Optical Detection DATE: 18/06/26 12:36:12 GMT FROM: Eleonora Troja at GSFC Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jesus Gonzalez (UNAM), Carlos Roman-Zuniga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report: We observed the field of GRB 180626A (Evans, et al., GCN 22850) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronomico Nacional on Sierra San Pedro Martir from 2018/06 26.42 to 2018/06 26.43 UTC (1.61 to 2.06 hours after the BAT trigger), obtaining a total of 0.36 hours exposure in the r and i bands. For a source at the position of the UVOT counterpart, in comparison with the SDSS DR9 catalog, we obtain the following detections:   r    = 21.57 +/- 0.22   i    = 20.91 +/- 0.13 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. These magnitudes are fainter than the values reported by Martone et al. (GCN 22854) suggesting that the source is indeed the fading GRB afterglow. We thank the staff of the Observatorio Astronomico Nacional in San Pedro Martir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22857 SUBJECT: GRB 180626A: Swift/UVOT Detection DATE: 18/06/26 15:22:56 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (UCL-MSSL) and P. A. Evans (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 180626A 123 s after the BAT trigger (Evans et al., GCN Circ. 22850). A fading source consistent with the XRT position (Osborne et al. GCN Circ. 22852) and also seen by Martone et al. (GCN Circ. 22854) and Troja et al. (GCN Circ. 22855) is detected in the initial UVOT exposures. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the finding chart (FC) and early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 123 273 147 20.57 ± 0.22 white 633 1033 190 >21.4 v 665 6473 452 >20.2 b 591 5858 246 >20.4 u 336 6936 529 >20.7 w1 714 6882 432 >21.0 m2 5043 6677 393 >20.1 w2 641 6268 432 >21.3 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22859 SUBJECT: GRB 180626A: COATLI Optical Detection DATE: 18/06/26 17:10:10 GMT FROM: Alan M. Watson at Instituto de Astronomia UNAM Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), William H. Lee (UNAM), Carlos Román-Zúñiga (UNAM), Alexander Kutyrev (GSFC), and Eleonora Troja (GSFC) report: We observed the field of GRB 180626A (Evans et al., GCN 22850) with the COATLI 50-cm telescope and interim imager at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir (http://coatli.astroscu.unam.mx) from 2018-06-20 08:21:50.6 to 11:18:41.7 UTC (from 33.7 seconds after the trigger or 17.9 seconds after the alert to 2.95 hours after the trigger), obtaining a total of 7020 seconds of exposure in the w filter. Within the enhanced XRT error region (Osborne et al., GCN Circ. 22852), we detect the afterglow previously reported by Evans et al. (GCN Circ. 22850), Martone et al. (GCN Circ. 22854), and Breeveld et al. (GCN Circ. 22857) with w = 21.4 +/- 0.9 In our first set of 30 images each of 5 seconds of exposure, from 08:21:50.6 to 08:27:10.1 UTC, we do not detect the afterglow with a 10-sigma limiting magnitude of w > 19.2 These magnitudes are calibrated against the Pan-STARRS1 catalog and the USNO-B1 catalog (adjusted to an approximate AB system) and are not corrected for Galactic extinction in the direction of the GRB. We thank the COATLI technical team (Fernando Ãngeles, Oscar Chapa, Salvador Cuevas, Alejandro Farah, Jorge Fuentes, Rosalía Langarica, Fernando Quirós, and Carlos Tejada) and the staff of the Observatorio Astronómico Nacional. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22860 SUBJECT: GRB 180626A: Swift-XRT refined Analysis DATE: 18/06/26 18:28:59 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), S.L. Gibson (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), A. Tohuvavohu (PSU), S. J. LaPorte (PSU) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.6 ks of XRT data for GRB 180626A (Evans et al. GCN Circ. 22850), from 129 s to 22.4 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 22852). The light curve can be modelled with an initial power-law decay with an index of alpha=0.21 (+0.14, -0.15), followed by a break at T+2992 s to an alpha of 0.90 (+0.11, -0.10). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.01 (+/-0.11). The best-fitting absorption column is 2.2 (+/-0.4) x 10^21 cm^-2, in excess of the Galactic value of 3.5 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (4.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.2 (+/-0.4) x 10^21 cm^-2 Galactic foreground: 3.5 x 10^20 cm^-2 Excess significance: 8.0 sigma Photon index: 2.01 (+/-0.11) 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 0.028 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x 10^-12 (1.4 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00844615. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22861 SUBJECT: GRB 180626A: KAIT Optical Upper Limit DATE: 18/06/26 19:58:36 GMT FROM: Weikang Zheng at UC Berkeley WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to GRB 180626A (Evans et al., GCN 22850; Gotz et al., GCN 22851) starting at 08:23:31 UT, 135 s after the Swift/BAT trigger. Observations were performed with an automatic sequence in the clear (roughly R), V, and I filters, and the exposure time was 20 s per image. Since the INTEGRAL trigger was received earlier than the Swift trigger, KAIT responed to the INTEGRAL trigger first. Unfortunately the UVOT afterglow location (Evans et al., GCN 22850) is outside our field of view for the first few images. We later manually re-pointed to the UVOT afterglow location starting at 08:52:10 UT about 30 minutes after the Swift/BAT trigger, with the updated exposure time of 60 s per image. We do not detect the afterglow at the reported UVOT location (Evans et al., GCN 22850) in our single image, nor in the co-added images. The typical limiting magnitude of our single clear image is about 19.5 mag calibrated to the PS1 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22862 SUBJECT: GRB 180626A: Swift-BAT refined analysis DATE: 18/06/26 20:41:06 GMT FROM: Hans Krimm at NSF/NASA-GSFC H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), P. A. Evans (U Leicester), 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-239 to T+526 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180626A (trigger #844615) (Evans, et al., GCN Circ. 22850). The BAT ground-calculated position is RA, Dec = 243.569, 14.759 deg which is RA(J2000) = 16h 14m 16.6s Dec(J2000) = +14d 45' 32.8" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 35%. The mask-weighted light curve shows a multi-peaked structure. The first peak is from approximately T-10 to T+5 sec, with a second overlapping peak from T+5 to T+20 sec, followed by a weaker peak from T+20 to T+30 sec. T90 (15-350 keV) is 30.07 +- 1.42 sec (estimated error including systematics). The time-averaged spectrum from T-10.01 to T+25.59 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.64 +- 0.27, and Epeak of 47.7 +- 12.2 keV (chi squared 40.18 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 4.8 +- 0.2 x 10^-6 erg/cm2 and the 1-sec peak flux measured from T-3.69 sec in the 15-150 keV band is 4.1 +- 0.4 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.01 +- 0.06 (chi squared 46.26 for 57 d.o.f.). 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/844615/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22863 SUBJECT: IPN Triangulation of GRB 180626B (short) DATE: 18/06/26 21:01:58 GMT FROM: Dmitry Svinkin at Ioffe Institute K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova, and T. Cline on behalf of the Konus-Wind 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, and D. Palmer, 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 short-duration GRB 180626B was detected by Konus-Wind, Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), and Swift (BAT) at about 6441 s UT (01:47:21). 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: 214.555 (14h 18m 13s) +12.412 (+12d 24' 43") Corners: 212.075 (14h 08m 18s) +4.864 ( +4d 51' 52") 213.948 (14h 15m 48s) +11.502 (+11d 30' 08") 217.782 (14h 31m 08s) +21.164 (+21d 09' 51") 215.173 (14h 20m 42s) +13.338 (+13d 20' 17") --------------------------------------------- The error box area is 4.7 sq. deg, and its maximum dimension is 17.2 deg (the minimum one is 29 arcmin). The Sun distance was 109 deg. This box may be improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB180626_T06442/IPN/ The localization of this burst is inconsistent with that of the short burst GRB 180626C, which is being reported in the next GCN Circular. The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22864 SUBJECT: IPN Triangulation of GRB 180626C (short) DATE: 18/06/26 21:08:46 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, K. Hurley, on behalf of the IPN, 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, and S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team, report: The short-duration GRB 180626C was detected by Fermi (GBM; trigger 551697835), INTEGRAL (SPI-ACS), Konus-Wind, and Swift (BAT), at about 33831 s UT (09:23:51). 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: 278.579 (18h 34m 19s) +47.241 (+47d 14' 28") Corners: 290.010 (19h 20m 02s) +48.528 (+48d 31' 40") 290.186 (19h 20m 45s) +48.912 (+48d 54' 42") 265.423 (17h 41m 42s) +43.214 (+43d 12' 49") 264.736 (17h 38m 57s) +42.455 (+42d 27' 17") --------------------------------------------- The error box area is 6.85 sq. deg, and its maximum dimension is 18.81 deg (the minimum one is 22 arcmin). The Sun distance was 106 deg. This box may be improved. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB180626_T33832/IPN The localization of this burst is inconsistent with that of the short burst GRB 180626B, reported in GCN Circ. 22863. The time history and spectrum will be given in forthcoming GCN Circulars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22865 SUBJECT: GRB 180626A: RATIR Optical Observations DATE: 18/06/27 05:11:57 GMT FROM: Alan M. Watson at Instituto de Astronomia UNAM Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report: We observed the field of GRB 180626A (Evans, et al., GCN Circ. 22850) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2018/06 27.16 to 2018/06 27.20 UTC (19.60 to 20.46 hours after the BAT trigger), obtaining a total of 0.71 hours exposure in the r and i bands. For a source at the position of the UVOT counterpart, in comparison with the SDSS DR9 catalog, we obtain the following detections: r = 22.39 +/- 0.20 i = 21.92 +/- 0.15 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. The source flux has faded approximately as t^-0.35 since our previous observations (Troja et al., GCN Circ. 22855). We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22866 SUBJECT: Konus-Wind observation of GRB 180626B DATE: 18/06/27 13:26:58 GMT FROM: Anna Kozlova at Ioffe Institute A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The short-duration GRB 180626B (IPN Triangulation: Hurley et al., GCN Circ. 22863) triggered Konus-Wind at T0=6442.786 s UT (01:47:22.786). The burst light curve shows a single pulse which starts at ~T0-0.1 s and has a total duration of ~0.3 s. The emission is seen up to ~2 MeV. As observed by Konus-Wind, the burst had a fluence of 7.69(-1.24,+1.35)x10^-7 erg/cm2, and a 16-ms peak flux, measured from T0+0.004 s, of 7.35(-2.79,+3.01)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+0.192 s) is best fit in the 20 keV - 4 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.13(-0.54,+0.73) and Ep = 218(-43,+60) keV (chi2 = 23/26 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.7 (chi2 = 23/25 dof). The spectrum near the maximum count rate (measured from T0 to T0+0.064 s) is best fit in the 20 keV - 4 MeV range by a power law with exponential cutoff model with alpha = -0.08(-0.59,+0.87) and Ep = 294(-70,+116) keV (chi2 = 14/16 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.3 (chi2 = 14/15 dof). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180626_T06442/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22868 SUBJECT: Konus-Wind observation of GRB 180626C DATE: 18/06/28 11:22:16 GMT FROM: Anna Kozlova at Ioffe Institute A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The short-duration GRB 180626C (IPN triangulation: Svinkin et al., GCN 22864) triggered Konus-Wind at T0=33832.424 s UT (09:23:52.424). The burst light curve shows a single pulse which starts at T0-40 ms and has a total duration of ~340 ms. As observed by Konus-Wind, the burst had a fluence of 6.13(-1.15,+2.18)x10^-7 erg/cm2, and a 16-ms peak flux, measured from T0-0.032 s, of 7.87(-2.06,+3.15)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). Since the most intense part of the burst was detected before the trigger, the spectral analysis was performed using the KW 3-channel light curve data. Modeling the KW 3-channel time-integrated spectrum (from T0-0.04 s to T0+0.336 s) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -0.87 (-0.23,+0.31), and Ep = 406 (-113,+225) keV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180626_T33832/ All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22869 SUBJECT: Konus-Wind observation of GRB 180626A DATE: 18/06/29 10:49:02 GMT FROM: Anna Kozlova at Ioffe Institute A. Kozlova, S. Golenetskii, R.Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The long GRB 180626A (Swift-BAT trigger #844615: Evans et al., GCN 22850; Krimm et al., GCN 22862; INTEGRAL detection: Gotz et al., GCN 22851) was detected by Konus-Wind (KW) in the waiting mode. The burst light curve shows a single emission episode with a duration of ~ 36 s. As observed by KW, the burst had a fluence of 7.21(-0.79,+0.97)x10^-6 erg/cm2 and a 2.944-s peak flux, measured from ~T0(BAT)-3.841 s, of 3.92(-0.49,+0.58)x10^-7 erg/cm2/s (both in the 20 keV - 10 MeV energy range). Modeling the KW 3-channel time-integrated spectrum (from ~T0(BAT)-9.7 s to ~T0(BAT)+25.6 s) by a simple power-law model yields a power law index of -2.19(-0.04,+0.05), chi2 = 2.5/1 dof. The KW light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB180626A/ All the quoted errors are estimated at the 1 sigma confidence level. All the presented results are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22870 SUBJECT: GRB 180626A: TSHAO optical upper limit DATE: 18/06/29 16:09:33 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Pozanenko (IKI), A. Kusakin (FAPHI), I. Reva (FAPHI), A. Volnova (IKI), M. Krugov (FAPHI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 180626A (Evans et al., GCN 22850; Gotz et al., GCN 22851) with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory starting on June 26 (UT) 16:26:21. We obtained several images in R-filter. The optical afterglow (Evans et al., GCN 22850; Martone et al. GCN 22854; Troja et al. GCN 22855; Watson et al. GCN 22859) is not detected in a stacked image. Preliminary photometry of the field is following. Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) 2018-06-26 16:26:21 0.41918 R 99*120 n/d n/d 21.5 The photometry is based on several nearby SDSS-DR10 stars. Ref.stars SDSS-DR9_id R(Lupton) J161422.32+144433.2 15.113 J161357.84+144752.0 13.989 J161440.94+144745.0 13.136 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22871 SUBJECT: GRB 180626C: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 551697835) DATE: 18/06/30 03:46:01 GMT FROM: Michael Coughlin at Caltech/LIGO Michael W. Coughlin (Caltech), Leo P. Singer (NASA GSFC), Tomás Ahumada (UMD), S. Bradley Cenko (NASA GSFC), Shaon Ghosh (UWM), Mansi M. Kasliwal (Caltech), Eric C. Bellm (UW), V. Zach Golkhou (UW), Ludwig Rauch (DESY), Robert Stein (DESY), on behalf of the ZTF and GROWTH collaborations and the KPED team We observed the localization region of the short GRB 180626C (trigger 551697835) 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 r- and g-band images covering 275 square degrees beginning at 10:52 UT on 2018 June 26 (1:29 hours after the burst trigger time), corresponding to ~ 36% of the probability enclosed in the localization region. Using the IPN updated localization of GRB 180626C available the next day, we observed the new region with ZTF beginning at 05:01 UT on 2018 June 27 (19:43 hours after the trigger time). The observations covered 230 square degrees, corresponding to ~ 87% of the probability enclosed in the localization region. The images were processed through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts. 45 high-significance transient and variable candidates were identified by our pipeline in the area observed, all of which had previous detections with ZTF in the days and weeks prior to the GRB trigger time (e.g., supernovae, active galactic nuclei). Out of the 45 transients, only 1 transient was within the IPN localization region, but the object has previous detections at similar magnitudes. No viable optical counterparts were thus identified. We would like to highlight one interesting object discovered in the ZTF fields on the first night (it does not fall into the IPN localization region) and later followed up with the Kitt Peak EMCCD Demonstrator (KPED) on the Kitt Peak 84 inch telescope on June 27. Located at RA: 19:48:49.1 , DEC: +46:30:36.1, ZTF18aauebur was first detected by ZTF June 25.30 (1 day before the trigger); it is a rapidly evolving transient that has gone from g = 18.4 to g = 20.5 in 1.92 days. An underlying source is present at this location in Pan-STARRS DR1 and GALEX. Given the low Galactic latitude, it may be a stellar flare. The median 5 sigma upper limit for an isolated point source in our images was r > 20.9 and g > 20.9 mag for the observations made on June 26 and r > 21.2 and g > 21.0 mag for the observations made on June 27. ZTF is a project led by PI S. R. Kulkarni at Caltech (see ATEL #11266 ), and includes IPAC; WIS, Israel; OKC, Sweden; JSI/UMd, USA; UW, USA; DESY, Germany; NRC, Taiwan; UW Milwaukee, USA and LANL USA. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. Alert distribution service provided by DIRAC@UW. Alert filtering is being undertaken by the GROWTH marshal system, supported by NSF PIRE grant 1545949. [GCN OPS NOTE(01jul18): Per author's request, the "A"s in the Subject-line and in the two places in the first paragraph were changed to "C"s. And the Trigger number in the Subject-line was changed to 551697835.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22874 SUBJECT: GRB 180626C / Fermi trigger 551697835: MASTER inspection DATE: 18/06/30 16:18:31 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tiurina, A.Kuznetsov, V.Chazov, I. Gorbunov, D. Vlasenko, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov Lomonosov Moscow State University,SAI R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias A. Tlatov, V.Senik, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory R. Podesta, F. Podesta, C. Lopez, C.Francile Observatorio Astronomico Felix Aguilar (OAFA) H.Levato, Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) D. Buckley South African Astronomical Observatory O. Gres, N.M.Budnev , Yu.Ishmuhametova Irkutsk State University A. Gabovich, V. Yurkov, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) , located in Teyde Observatory (IAC, Spain), was pointed to the IPN (Svinkin et al. GCN22864, Kozlova et al. GCN22868) Triangulation GRB180626C / Fermi trigger 551697835 (GRB_Time 18/06/26 09:23:50.65UT; RA,Dec(2000)=19h 00m 14s +44d 49' 12" (GRB_ERROR: 8.21 deg radius, statistical only , see https://gcn.gsfc.nasa.gov/other/551697835.fermi) also inspected by ZTF (Coughlin et al. GCN22871) at 2018-06-26 21:37:30UT-22:53:48 with unfiltered mlim=19.1 (180s expositions); 2018-06-27 03:34:57-03:53:20 with mlim=19.7 on summary expositions (5sigma, exp=540s). The observations started on zenit distance = 41 degrees. The sun altitude was -17.66 degree. MASTER-SAAO robotic telescope located in South Africa started Fermi inspection 5834 sec after notice time and 37433 sec after trigger time at 2018-06-26 19:51:28 UT. The 5-sigma upper limit on our second (180s exposure) set is about 16.2mag. The observations started on zenit distance = 89 degrees, galaxy latitude b = 22 degree. The moon (98 % bright part) is 64 degrees above the horizon. The distance between moon and object is 69. The sun altitude was -52.2 degree. MASTER-Amur robotic telescope, located at BSPU, was pointed to Fermi trigger 551697835 on 2018-06-27 14:09:39UT, and observed till 14:57:32.584UT with mlim=18.0(180s exp) MASTER-Kislovodsk robotic telescope, located at Kislovodsk Solar Station of Pulkovo observatory, started Fermi trigger inspection at 2018-06-27 20:53:26 UT. The 5-sigma upper limit on our first (180s exposure) set is about 18.8mag . The observations started on zenit distance = 6 degrees, galaxy latitude b = 22 degree. The moon (100 % bright part) is 26 degrees above the horizon. The distance between moon and object is 68 .The sun altitude is -22.8 degree. New OT, that could be connected with GRB, wasn't found. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22878 SUBJECT: GRB 180626B : GOTO optical observations DATE: 18/07/01 21:14:54 GMT FROM: Danny Steeghs at U.of Warwick/GOTO J.Lyman, D.Steeghs, K.Ulaczyk, A.Levan, B.Gompertz (U. Warwick), N.Tanvir (U. Leicester), M.Dyer (U. Sheffield), K. Ackley, D.Galloway, E.Rol (Monash U.), G.Ramsay (Armagh O.), V.Dhillon (U. Sheffield), P.O'Brien (U. Leicester), S.Poshyachinda (NARIT), D.Pollacco (U. Warwick), E.Thrane (Monash U.) report on behalf of the GOTO collaboration: In response to the short-duration GRB 180626B (GCN 22863, 22866), the Gravitational-wave Optical Transient Observer (GOTO) observed the IPN triangulation region as reported in Hurley et al. (GCN 22863). Observations were spread over several telescope array pointings, beginning 2018-06-26T21:52 UT (20.1 hours after the burst) and employed sets of 3x120s exposures in our wide L filter (400-700nm). Approximately 83% of the IPN region was covered on-chip. These fields were repeated in subsequent nights to permit difference imaging analysis and typically achieved a 5 sigma limiting magnitude of V=19.9-20.1 (based on zeropoints derived from APASS crossmatching). We made use of the GLADE galaxy catalog to pay particular attention to possible source candidates near galaxies within 200 Mpc. No significant sources that could be credibly associated with the GRB were detected. GOTO is operated at the La Palma observing facilities of the University of Warwick on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT) and the Instituto de Astrofisica de Canarias (IAC) https://goto-observatory.org/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22879 SUBJECT: GRB 180626C : GOTO optical observations DATE: 18/07/01 21:15:44 GMT FROM: Danny Steeghs at U.of Warwick/GOTO J.Lyman, D.Steeghs, K.Ulaczyk, A.Levan, B.Gompertz (U. Warwick), N.Tanvir (U. Leicester), M.Dyer (U. Sheffield), K. Ackley, D.Galloway, E.Rol (Monash U.), G.Ramsay (Armagh O.), V.Dhillon (U. Sheffield), P.O'Brien (U. Leicester), S.Poshyachinda (NARIT), D.Pollacco (U. Warwick), E.Thrane (Monash U.) report on behalf of the GOTO collaboration: In response to the short-duration GRB 180626C (GCN 22864, 22868, 22871, 22874), the Gravitational-wave Optical Transient Observer (GOTO) observed the IPN triangulation region as reported in Svinkin et al. (GCN 22864). Observations were spread over several telescope array pointings, beginning 2018-06-26T22:21 UT (13 hours after the burst) and employ sets of 3x120s exposures in our wide L filter(400-700nm). Approximately 95% of the IPN region was covered on-chip. These fields were repeated in subsequent nights to permit difference imaging analysis and typically achieved a 5 sigma limiting magnitude of V=20.1-20.3 (based on zeropoints derived from APASS crossmatching). We made use of the GLADE galaxy catalog to pay particular attention to possible source candidates near galaxies within 200 Mpc. Similar to the searches reported in Coughlin et al. (GCN 22871) and Lupinov et al. (GCN 22874), we find no significant sources that could be credibly associated with the GRB. GOTO is operated at the La Palma observing facilities of the University of Warwick on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT) and the Instituto de Astrofisica de Canarias (IAC) https://goto-observatory.org/