///////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21193 SUBJECT: Swift Trigger 755873: a possible GRB DATE: 17/06/04 22:00:29 GMT FROM: David Palmer at LANL K. L. Page (U Leicester), S. D. Barthelmy (GSFC), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC) and D. M. Palmer (LANL) report on behalf of the Swift Team: At 21:30:52 UT, the Swift Burst Alert Telescope (BAT) triggered on a possible GRB (trigger=755873). Swift slewed immediately to the location. The BAT on-board calculated location is RA, Dec 200.808, +64.198, which is RA(J2000) = 13h 23m 14s Dec(J2000) = +64d 11' 52" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a large (~2000 cnts/sec) ramp up to the trigger time, then several overlapping peaks lasting ~50 sec with a maximum of ~4000 cnts/sec. There is also a 3000 cnt/sec drop at T+80 sec. This plus an anomalously large ratio in the rate-trigger significance and the image significance makes this event uncertain. The XRT began observing the field at 21:32:52.9 UT, 120.5 seconds after the BAT trigger. No source was detected in 990 s of promptly downlinked data. We are waiting for the full dataset to detect and localise the XRT counterpart. UVOT took a finding chart exposure of 150 seconds with the White filter starting 124 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 25% of the BAT 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 BAT 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 0.02. This event occurred as Swift was on the fringes of the SAA, and the intensities of the apparent BAT lightcurve and image strength are not in simple agreement. Due to the non-detection of an afterglow by the XRT, we cannot confidently determine whether this is an astrophysical event. Final determination of the reality of this event will require the full downlinked dataset. Burst Advocate for this burst is K. L. Page (klp5 AT leicester.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: 21194 SUBJECT: Swift Trigger 755873: D50 optical limits DATE: 17/06/04 22:54:26 GMT FROM: Martin Jelinek at Astro.Inst-AVCR,Ondrejov Martin Jelinek, Jan Strobl and Rene Hudec (ASU CAS, Ondrejov, CZ) report: We observed the location of the possible GRB (Swift tigger 755873, Page et al., GCNC 21193) with the 0.5m robotic telescope D50 located in Ondrejov, Czech Republic. The unfiltered CCD observations started 61s after the trigger. No new or variable object is detected within and in the close proximity of the BAT errorbox. The limiting magnitude of our unfiltered 24x10s combined image, which has the mean exposure time 21:40:09UT, i.e. 8.5min post GRB, is R>19.6. ///////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21199 SUBJECT: Swift Trigger 755873: MASTER Net optical observations DATE: 17/06/05 10:40:54 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs O. Ershova Irkutsk State University V. Lipunov, V.Kornilov, N.Tyurina, E.Gorbovskoy, D.Kuvshinov, A.V.Krylov, I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias O.Gres, N.M.Budnev Irkutsk State University D.Buckley South African Astronomical Observatory A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory A.Gabovich, V.Yurkov, Yu.Sergienko Blagoveschensk Educational State University, Blagoveschensk R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA), National University of San Juan, Argentina H. Levato, C. Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina MASTER Kislovodsk was observed Swift Trigger 755873 since 62 sec to 2957 sec after trigger time in SWIFT error box (K.L. Page et al., GCN # 21193). MASTER -IAC and MASTER-Kislovodsk had credible conditions for observations. MASTER-Kislovodsk was pointed to the Swift Trigger 755873 12 sec after notice time and 62 sec after trigger time at 2017-06-04 21:31:54 UT. On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box. The 5-sigma upper limit has been about 16.9mag . This limit in agreement with Jelinek et al. (GCN #21194) The observations made on zenit distance = 38 degrees, galaxy latitude b = 53 degree. The moon (81 % bright part) is 20 degrees above the horizon. The distance between moon and object is 69. The sun altitude is -23.5 degree. The object can be observed till sunrise at 2017-06-05 01:28:56 . MASTER-IAC robotic telescope located in IAC was pointed to the Swift Trigger 755873 1001 sec after notice time and 1051 sec after trigger time at 2017-06-04 22:05:58 UT. The 5-sigma upper limit has been about 20.2 mag The observations made on zenit distance = 36 degrees, galaxy latitude b = 53 degree. The moon (82 % bright part) is 56 degrees above the horizon. The distance between moon and object is 69 The sun altitude is -23.6 degree. The object can be observed till sunrise at 2017-06-05 06:07:42. All our observations are in agreement with Ondrejov Robotic Telescope Limit (Jelinek et al. GCN #21194 ). This message cab be cited. ///////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 21202 SUBJECT: Swift trigger 755873: Swift BAT and XRT refined analysis DATE: 17/06/05 15:12:53 GMT FROM: Amy Lien at GSFC S. D. Barthelmy (GSFC), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), and D. M. Palmer (LANL) report on behalf of the Swift team: We report further analysis of the Swift/BAT trigger #755873 (Page et al., GCN Circ. 21193) using data from the recent telemetry downlink. The BAT ground analysis uses the data set from T-240 to T+962 sec. The BAT image significance is only 1.9 sigma. Also, the mask-weighted light curve does not show anything significant. XRT collected 4.5 ks of Photon Counting mode data between 134 s and 13.1 ks after the BAT trigger. No X-ray was detected within the 90% BAT error circle, to an 3-sigma upper limit of 3.1x10^-3 count s^-1. We therefore conclude that this trigger is due to noise fluctuation. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/755873/BA/ /////////////////////////////////////////////////////////////////////////