//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18000 SUBJECT: Swift trigger 648437: A GRB or a burst from 1RXS J125754.7+141850 DATE: 15/07/10 00:56:43 GMT FROM: David Palmer at LANL M. G. Bernardini (INAF-OAB), S. D. Barthelmy (GSFC), P. D'Avanzo (INAF-OAB), A. Melandri (INAF-OAB), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 00:28:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located a short burst consistent with the location of the ROSAT faint source 1RXS J125754.7+14185 (trigger=648437). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 194.497, +14.305 which is RA(J2000) = 12h 57m 59s Dec(J2000) = +14d 18' 18" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single spike structure with a duration of about 0.25 sec. The peak count rate was ~8000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 00:28:51.6 UT, 49.2 seconds after the BAT trigger. Using promptly downlinked data we find an X-ray source with an enhanced position: RA, Dec 194.4710, 14.3183 which is equivalent to: RA(J2000) = 12h 57m 53.03s Dec(J2000) = +14d 19' 05.8" with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 102 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. We cannot determine whether the source is fading at the present time. This position is 28.6 arcseconds from that of a known X-ray source: 1RXS J125754.7+141850 in the ROSAT RASSFSC catalogue. UVOT took a finding chart exposure of 150 seconds with the White filter starting 53 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 none of the XRT error circle. 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 0.03. This source location is consistent with the source 1RXS J125754.7+141850, an object in the ROSAT RASSFSC. This catalog has 106k sources, and so the possibility of a chance coincidence cannot be ruled out. This burst is comparable in hardness and other aspects to a typical short GRB. For this reason, we cannot confirm whether this burst comes from the previously-known source or a new sGRB with the immediately-available data. The complete downlinked dataset and further observations will be required to determine the nature of this source. Burst Advocate for this burst is M. G. Bernardini (grazia.bernardini AT brera.inaf.it). 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: 18001 SUBJECT: GRB 150710A: RATIR Observations DATE: 15/07/10 04:58:33 GMT FROM: Nat Butler at Az State U Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We observed the field of possible GRB 150710A (trigger 648437; Bernardini, et al., GCN 18000) 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 2015/07 10.16 to 2015/07 10.20 UTC (3.47 to 4.31 hours after the BAT trigger), obtaining a total of 0.71 hours exposure in the r, i, and z bands. For a source within the Swift-XRT error circle, in comparison with the SDSS DR9 catalog, we obtain the following upper limits (3-sigma): r > 23.4 i > 23.2 z > 19.4 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the possible GRB. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. Further observations are ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18002 SUBJECT: GRB 150710A: Swift-BAT refined analysis DATE: 15/07/10 13:52:31 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), M. G. Bernardini (INAF-OAB), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), 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-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 150710A (trigger #648437) (Bernardini, et al., GCN Circ. 18000). The BAT ground-calculated position is RA, Dec = 194.484, 14.309 deg, which is RA(J2000) = 12h 57m 56.3s Dec(J2000) = +14d 18' 32.3" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows two, possibly 4, overlapping peaks. T90 (15-350 keV) is 0.15 +- 0.06 sec (estimated error including systematics). The time-averaged spectrum from T+0.02 to T+0.22 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.63 +- 0.20. The fluence in the 15-150 keV band is 7.1 +- 0.9 x 10^-8 erg/cm2. The 1-sec peak photon flux measured from T-0.38 sec in the 15-150 keV band is 0.7 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level. These results are entirely consistant with a short GRB. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/648437/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18003 SUBJECT: Konus-Wind observation of GRB 150710A (Swift trigger 648437) DATE: 15/07/10 13:58:12 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The short-duration GRB 150710A (Swift trigger 648437: Bernardini, et al., GCN Circ. 18000) triggered Konus-Wind at T0=1681.682 s UT (00:28:01.682). The burst light curve shows a short, double-peaked pulse with a total duration of ~0.1 s. As observed by Konus-Wind, the burst had a fluence of (3.7 ± 0.7)x10^-7 erg/cm2, and a 16-ms peak flux, measured from T0-0.048 s, of (7.6 ± 1.5)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). Since the bulk of the burst emission was detected before the trigger, the spectral analysis was performed using the KW 3-channel light curve data. Modeling the 3-channel time-integrated spectrum (from T0-0.048 s to T0+0.048 s) by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -0.28 ± 0.54, and Ep = 308 ± 70 keV. The K-W light curve of this burst is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB150710_T01681/ Following Bernardini, et al. (GCN Circ. 18000), we note, that the burst, as observed by Konus-Wind, is comparable in hardness and other aspects to a typical short GRB from the KW sample. The figure showing the GRB 150710A position in the hardness-duration diagram (logT50-logHR32) of 1143 KW bright GRBs is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB150710_T01681/HR32vsT50.png The contours denote the 1, 2, and 3 sigma confidence regions for two-dimensional Gaussian distributions. The vertical dashed line at T50=0.6 s marks the boundary between short and long KW GRBs. All the quoted errors are estimated at the 1 sigma confidence level. All the presented results are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18005 SUBJECT: Swift-XRT observations of GRB 150710A DATE: 15/07/10 18:09:11 GMT FROM: Maria Grazia Bernardini at INAF/Brera M.G. Bernardini, P. D'Avanzo, A. Melandri, S. Campana, G. Tagliaferri (INAF-OAB), D. Burrows (PSU), K. Page and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: We analyzed the full dataset of Swift-XRT observations of the Swift trigger 648437 (Bernardini et al., GCN Circ. 18000), classified as short GRB 150710A (Barthelmy et al., GCN Circ. 18002, Golenetskii et al. GCN Circ. 18003), comprising 11.2 ks in Photon Counting (PC) mode. One X-ray source has been detected within the BAT error circle at the following position: RA (J2000.0): 194.47045 = 12:57:52.91 Dec (J2000.0): 14.31807 = +14:19:05.0 Error: 2.8 arcsec (radius, 90% conf.) This position is consistent with the location of a ROSAT faint source 1RXS J125754.7+14185. In an initial 0.98 ks observation carried out between T+57s and T+1056s, the source has an initial count-rate of (3.22E-02 ± 6.3E-03) ct/s. Then in a subsequent 10 ks observation, carried out between T+4.9 ks and T+34.5 ks, it is no longer detected down to a 3sigma UL of 1.3E-3 ct/s. The source is near the edge of the Virgo cluster, but the non-detection of any host galaxy by RATIR (Butler et al., GCN Circ. 18001) argues against the possibility of this being a giant SGR flare from a galaxy in the Virgo cluster. Given the observed fading, we propose this source as the X-ray counterpart of GRB 150710A. We also note the possible presence of a second source at the following position: RA (J2000.0): 194.4810088073 = 12:57:55.44 Dec (J2000.0): 14.317574983 = +14:19:03.3 Error: 6.0 arcsec (radius, 90% conf.) also consistent with the location of 1RXS J125754.7+14185. The source is detected at a low significance, and it is not possible with present data to assess if is real or not. Further observation can confirm if this second source is real and if it is possibly related to 1RXS J125754.7+14185. Otherwise, we cannot exclude that the observed X-ray emission from Source #1 is due to a brightening from 1RXS J125754.7+14185. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18006 SUBJECT: GRB 150710A: host galaxy for Swift XRT second candidate DATE: 15/07/10 19:18:38 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov (Lomonosov Moscow State University) There is SDSS9 galaxy at second XRT candidate postion (Bernardini et al., GCN 18005) J125755.36+141905.7 . Rmag = 22.1, gmag = 24 That is correspond to z ~ 1 for big galaxy like to Milky Way. The follow up observation for redshift is needed. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18008 SUBJECT: GRB 150710A: Swift/UVOT Upper Limits DATE: 15/07/10 20:15:24 GMT FROM: Massimiliano de Pasquale at IASF-Palermo M. De Pasquale (UCL-MSSL) and M.G. Bernardini (INAF/OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150710A 54 s after the BAT trigger (Bernardini et al., GCN Circ. 18000). No optical afterglow consistent with the position of the XRT sources (Bernardini et al., GCN Circ 18005) 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 54 204 147 >20.6 u_FC 266 516 246 >19.9 white 54 1017 334 >21.1 v 595 1050 41 >18.1 b 521 714 39 >19.1 u 266 516 285 >20.0 uw1 645 837 39 >18.5 um2 620 812 39 >18.2 uw2 571 1043 58 >19.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).