//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32213 SUBJECT: Swift GRB220618.38: Global MASTER-Net observations report DATE: 22/06/18 09:18:34 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (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 (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-OAGH robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) was pointed to the Swift GRB220618.38 (trigger No 1110821,02h 35m 51.84s , +55d 12m 50.4s, R=0.05) errorbox 19 sec after notice time and 50 sec after trigger time at 2022-06-18 09:11:20 UT, with upper limit up to 12.1 mag. The observations began at zenith distance = 73 deg. The sun altitude is -29.4 deg. The galactic latitude b = -4 deg., longitude l = 138 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2009312 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 56 | MASTER-OAGH | C | 10 | 12.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32214 SUBJECT: GRB 220618A: Swift detection of a burst DATE: 22/06/18 09:25:56 GMT FROM: Kim Page at U.of Leicester E. Troja (NASA/GSFC/UMCP), C. Gronwall (PSU), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 09:10:29 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 220618A (trigger=1110821). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 38.966, +55.214 which is RA(J2000) = 02h 35m 52s Dec(J2000) = +55d 12' 49" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak structure with a duration of about 40 sec. The peak count rate was ~800 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 09:12:53.1 UT, 143.2 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 38.98802, 55.21543 which is equivalent to: RA(J2000) = 02h 35m 57.12s Dec(J2000) = +55d 12' 55.5" with an uncertainty of 4.3 arcseconds (radius, 90% containment). This location is 45 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 https://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 (4.74 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 8.9 (+7.86/-6.18) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 6.79e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 151 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 large, but uncertain, extinction expected. Burst Advocate for this burst is E. Troja (nora.gsfc AT gmail.com). 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: 32216 SUBJECT: GRB 220618A: Enhanced Swift-XRT position DATE: 22/06/18 13:14:20 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 345 s of XRT Photon Counting mode data and 1 UVOT images for GRB 220618A, 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 = 38.98602, +55.21568 which is equivalent to: RA (J2000): 02h 35m 56.65s Dec (J2000): +55d 12' 56.4" with an uncertainty of 2.2 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: 32218 SUBJECT: GRB 220618A: Swift/UVOT Upper Limits DATE: 22/06/18 15:40:50 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and E. Troja (NASA/GSFC/UMCP) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 220618A 151 s after the BAT trigger (Troja et al., GCN Circ. 32214). No optical afterglow consistent with the XRT position (Troja et al. GCN Circ. 32214) 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 151 301 147 >19.8 u_FC 309 559 246 >18.9 white 151 609 167 >19.8 v 641 649 8 >17.4 b 565 585 19 >17.9 u 309 559 246 >18.9 w2 617 637 19 >18.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.391 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32219 SUBJECT: GRB 220618A: BOOTES-5/JGT early optical upper limit DATE: 22/06/18 17:16:46 GMT FROM: Youdong HU at IAA-CSIC Y.-D. Hu, E. Fernandez-Garcia, I. Perez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia, R. Sanchez-Ramirez (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar and I. Carrasco (UMA), I. H. Park (SKKU) on behalf of a larger collaboration, report: Following the detection of GRB 220618A by Swift (Troja et al. GCNC 32214), the BOOTES-5/JGT 0.6m robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) observed the GRB location starting on Jun 18, 09:10:39 UT (~10 s after trigger). In the early co-added image (20 x 10 s exposures in the clear filter), no optical afterglow is detected within the Swift/XRT error region (Osborne et al. GCNC 32216) down to 19.5 mag. This non-detection is consistent with the UVOT results (Kuin et al. GCNC 32218) and MASTER results (Lipunov et al. GCNC 32213). We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for their excellent support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32221 SUBJECT: GRB 220618A: Swift-XRT refined Analysis DATE: 22/06/18 18:35:19 GMT FROM: Phil Evans at U of Leicester M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester) and E. Troja report on behalf of the Swift-XRT team: We have analysed 6.0 ks of XRT data for GRB 220618A (Troja et al. GCN Circ. 32214), from 131 s to 28.0 ks after the BAT trigger. The data comprise 235 s in Windowed Timing (WT) mode (the first 10 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 32216). The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=2.1 (+/-0.4). At T+399 s the decay steepens to an alpha of 4.6 (+3.4, -0.7) before breaking again at T+1148 s to a final decay with index alpha=0.26 (+0.52, -0.26). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.62 (+/-0.11). The best-fitting absorption column is 5.9 (+0.6, -0.5) x 10^21 cm^-2, in excess of the Galactic value of 4.7 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 3.0 x 10^-11 (8.4 x 10^-11) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 5.9 (+0.6, -0.5) x 10^21 cm^-2 Galactic foreground: 4.7 x 10^21 cm^-2 Excess significance: 3.7 sigma Photon index: 2.62 (+/-0.11) If the light curve continues to decay with a power-law decay index of 0.26, the count rate at T+24 hours will be 6.9 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.1 x 10^-13 (5.8 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/01110821. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32238 SUBJECT: GRB 220618A: iTelescope T-19 upper limit DATE: 22/06/21 00:48:42 GMT FROM: Takanori Sakamoto at AGU Y. Koyanagi, K. Hasuda, E. Kiuchi, N. Shimizu, T. Sakamoto (AGU) We observed the field of GRB 220618A detected by Swift (Troja et al., GCN Circ. 32214) with the iTelescope.Net (http://www.itelescope.net) T19 (Planewave 17" CDK) telescope located at the New Mexico Skies Observatory (NM, USA). We took 10 images of 120 sec exposures in the Red filter starting from June 18 at 09:46:36 (UT), about 0.6 hours after the trigger and stopped at 10:09:40 (UT). We do not detect the optical afterglow in the individual images and the stacked image at the XRT position (Osborne et al., GCN Circ. 32216). The estimated five sigma upper limits of the combined image (total exposure of 1200 sec) is 17.8 using the USNO-B1 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32239 SUBJECT: GRB 220618A: Swift-BAT refined analysis DATE: 22/06/21 12:26:59 GMT FROM: Tyler Parsotan at UMBC/GSFC/CRESST II D. M. Palmer (LANL), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), 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 220618A (trigger #1110821) (Troja, et al., GCN Circ. 1110821). The BAT ground-calculated position is RA, Dec = 38.986, 55.218 deg which is RA(J2000) = 02h 35m 56.6s Dec(J2000) = +55d 13' 05.0" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 21%. The BAT light curve showed a single peak structure with a duration of about 40 sec. T90 (15-350 keV) is 96.00 +- 65.97 sec (estimated error including systematics). The time-averaged spectrum from -15.264 to 128.736 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.26 +- 0.85, and Epeak of 65.0 +- 16.9 keV (chi squared 53.40 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 2.2 +- 0.3 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+8.24 sec in the 15-150 keV band is 0.8 +- 0.4 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.61 +- 0.16 (chi squared 63.41 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/1110821/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 32241 SUBJECT: GRB 220618A: Fermi GBM detection DATE: 22/06/21 16:48:36 GMT FROM: Suraj Poolakkil at UAH S. Poolakkil (UAH) and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 09:10:19.59 UT on 18 June 2022, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 220618A (trigger 677236224 / 220618382) which was also detected by the Swift/BAT (Troja et al. 2022, GCN 32214). The angle from the Fermi LAT boresight at the GBM trigger time is 35 degrees. The GBM light curve consists of a single peak followed by some extended emission with a duration (T90) of about 44 s (50-300 keV). The time-averaged spectrum from T0-4.096 s to T0+24.576 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.30 +/- 0.13 and the cutoff energy, parameterized as Epeak, is 126 +/- 8 keV. The event fluence (10-1000 keV) in this time interval is (3.6 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+10.05 s in the 10-1000 keV band is 2.3 +/- 0.2 ph/s/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/"