//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22769 SUBJECT: GRB 180613A: Swift detection of a burst DATE: 18/06/13 15:53:16 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT A. Tohuvavohu (PSU), S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester), J.D. Gropp (PSU), J. A. Kennea (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU) and T. N. Ukwatta (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 15:36:18 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 180613A (trigger=840853). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 211.562, -43.076 which is RA(J2000) = 14h 06m 15s Dec(J2000) = -43d 04' 31" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual with an image trigger, the available BAT light curve shows no significant structure. The XRT began observing the field at 15:38:47.7 UT, 148.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 211.52004, -43.07158 which is equivalent to: RA(J2000) = 14h 06m 04.81s Dec(J2000) = -43d 04' 17.7" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 111 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 (6.50 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.5 (+3.67/-3.01) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 5.63e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 250 seconds with the U filter starting 154 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 19.2 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 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.09. Burst Advocate for this burst is A. Tohuvavohu (aaronb AT swift.psu.edu). 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: 22771 SUBJECT: GRB 180613A: Prompt enhanced Swift-XRT position DATE: 18/06/13 16:16:56 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Using promptly downlinked XRT event data for GRB 180613A, we find an enhanced XRT position of the afterglow: RA, Dec: 211.5204, -43.0722 which is equivalent to: RA (J2000) = 14 06 04.89 Dec (J2000) = -43 04 19.9 with an uncertainty of 2.0 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/840853. Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22772 SUBJECT: GRB 180613A: Possible host galaxy at XRT position, or star DATE: 18/06/13 16:20:33 GMT FROM: Alexander Kann at IAA-CSIC D. A. Kann and L. Izzo (HETH/IAA-CSIC) report: Inspection of archival DSS images of the enhanced XRT position (error radius 2.0", Evans, GCN #22771) of GRB 180613A (Tohuvavohu et al., GCN #22769) reveals a known source within the XRT error circle. This source is known in the USNO B1.0 catalog, and is also part of Gaia DR1/2 (source ID 6109389046377848320, with possible parallax of 0.98 +/- 0.62 mas, Gmag = 19.748). PS1 and SDSS do not cover this location. It is not possible to determine from the DSS2 image if this source is stellar or slightly extended. We suggest this source may be the host galaxy of this GRB, but it could also be a foreground star, as the stellar density of this field is quite high. [GCN OPS NOTE(13jun18): Per author's request, "Ecans" was changed to "Evans" in the second line.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22773 SUBJECT: GRB 180613A: Enhanced Swift-XRT position DATE: 18/06/13 21:08:20 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 615 s of XRT Photon Counting mode data and 1 UVOT images for GRB 180613A, 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 = 211.52057, -43.07237 which is equivalent to: RA (J2000): 14h 06m 4.94s Dec (J2000): -43d 04' 20.5" with an uncertainty of 4.9 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: 22774 SUBJECT: GRB 180613A: Swift-XRT refined Analysis DATE: 18/06/14 00:02:55 GMT FROM: Phil Evans at U of Leicester K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), P.A. Evans (U. Leicester) and A. Tohuvavohu report on behalf of the Swift-XRT team: We have analysed 8.3 ks of XRT data for GRB 180613A (Tohuvavohu et al. GCN Circ. 22769), from 155 s to 19.0 ks after the BAT trigger. The data comprise 95 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 22771). The light curve can be modelled with a power-law decay with a decay index of alpha=2.05 (+0.07, -0.06). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.04 (+0.17, -0.16). The best-fitting absorption column is 1.5 (+1.1, -0.9) x 10^21 cm^-2, consistent with the Galactic value of 6.5 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.45 (+0.20, -0.19) and a best-fitting absorption column of 2.0 (+1.1, -0.9) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.0 x 10^-11 (5.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.0 (+1.1, -0.9) x 10^21 cm^-2 Galactic foreground: 6.5 x 10^20 cm^-2 Excess significance: 2.5 sigma Photon index: 1.45 (+0.20, -0.19) If the light curve continues to decay with a power-law decay index of 2.05, the count rate at T+24 hours will be 2.9 x 10^-5 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.4 x 10^-15 (1.6 x 10^-15) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00840853. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22775 SUBJECT: GRB 180613A: Possible IR afterglow DATE: 18/06/14 01:45:46 GMT FROM: Antonio de Ugarte Postigo at IAA-CSIC C. C. Thoene (HETH/IAA-CSIC), N. Tanvir (Univ. of Leicester), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann, L. Izzo (both HETH/IAA-CSIC), G. Pugliese (API/U. Amsterdam), P. Schady (MPE) and D. Xu (NAO/CAS) report on behalf of the Stargate consortium: We observed the field of GRB 180613A (GCN 22769, Tohuvavohu et al.) with HAWKI at the VLT (ESO, Paranal, Chile) starting on June 13, 2018, at 22:51 UT (7.25 hours after the burst). Imaging observations were obtained in J, H and Ks filters with exposure times of 11-12 min under thin clouds but excellent seeing conditions (around 0.4 arcsec) and preliminary reductions provided by the observatory. The object reported in GCN 22772 (Kann & Izzo) is clearly detected and likely a foreground star. Inside the refined XRT error circle (GCN 22771, Evans) we detect a faint source in all three bands at the coordinates (errors +/-0.5 arcsec): RA 14:06:04.89 DEC -43:04:19.6 The source seems to be slightly extended to the NW and a point-like source at the SW end of it. This could possibly be the underlying host + afterglow. Further observations are needed to determine a possible fading of the source. Preliminary photometry gives J = 22.86 +/- 0.25 mag using aperture photometry centered on the point-like part of the source and compared to field stars from the 2MASS catalogue. We acknowledge the excellent support from ESO staff, in particular Frédéric Vogt, Ivan Aranda and Stephane Brillant and enjoyed the great new option to chat on Skype with the telescope during the observations. [GCN OPS NOTE(14jun18): Per author's request, the "days" in the 3rd line was changed to "hours".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22776 SUBJECT: GRB 180613A, Swift-BAT refined analysis DATE: 18/06/14 03:12:15 GMT FROM: Amy Lien at GSFC C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), 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+625 sec from the recent telemetry downlink, we report further analysis of BAT GRB 180613A (trigger #840853) (Tohuvavohu et al., GCN Circ. 22769). The BAT ground-calculated position is RA, Dec = 211.545, -43.082 deg which is RA(J2000) = 14h 06m 10.9s Dec(J2000) = -43d 04' 56.5" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%. The mask-weighted light curve shows some weak emission that starts at ~T+25 s and ends at ~T+80 s. T90 (15-350 keV) is 50.8 +- 8.4 sec (estimated error including systematics). Because this trigger occurred when BAT was in the process of resuming to normal operation from the recent reboot. The entire detector array had the lower level discriminators set to a value higher than the level of normal operations. Therefore, the standard spectral analyses are unavailable. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/840853/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22777 SUBJECT: GRB 180613A GROND observations DATE: 18/06/14 11:42:07 GMT FROM: Patricia Schady at MPE/Swift P. Schady, T. Schweyer, T.-W. Chen (all MPE Garching) and J. Bolmer (ESO Santiago) report: We observed the field of GRB 180613A (Swift trigger 840853; Tohuvavohu et al., GCN #22769) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile). Observations started at 23:30 UT on 2018-06-13, 7.9 hrs after the GRB trigger. They were performed at an average seeing of 1.5" and at an average airmass of 1.1. We do not detect the HAWKI source reported by Thoene et al. (GCN #2275). However, we note that the larger 4.9 arcsec uncertainty on the enhanced XRT position (Beardmore et al., GCN #22773) now includes two, brighter sources that are below the sensitivity of the DSS images. Source #1 lies at the SW edge of the enhanced XRT 90% error circle, at RA = 14:06:05.24 Dec = -43:04:21.6 with a preliminary magnitude r' = 23.1 +/- 0.1 mag. Source #2 lies at the NW edge of the enhanced XRT error circle, at RA = 14:06:05.24 Dec = -43:04:21.6 with r' = 22.9 +/- 0.1 mag. The above positions have an accuracy of 0.1" in both directions. Our g' band photometry is strongly affected by a nearby 5.6 mag star located SW of the GRB position, but source #1 is detected in all other GROND bands. Source #2 is detected in r', i' and z'. Our observations at the position of the XRT afterglow have preliminary 3 sigma upper limits of r' > 23.7 mag i' > 22.8 mag z' > 22.7 mag J > 21.5 mag H > 21.0 mag K > 20.4 mag All quoted magnitudes are in the AB system and are calibrated against GROND zeropoints and 2MASS field stars. They are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.08 in the direction of the burst (Schlafly & Finkbeiner 2011). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22778 SUBJECT: GRB 180613A GROND observations: correction DATE: 18/06/14 13:13:55 GMT FROM: Patricia Schady at MPE/Swift P. Schady (MPE, Garching) reports: We note a mistake in the position reported for source #2 in Schady et al. (GCN #22777), which should have been RA = 14:06:04.69 Dec = -43:04:17.7 There was also a mistake in our reference to Thoene et al. which should be GCN #22775, rather than GCN #2275. We apologise for any confusion that this error may have caused. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22779 SUBJECT: GRB 180613A: Swift/UVOT Upper Limits DATE: 18/06/14 19:10:11 GMT FROM: Mike Siegel at PSU/Swift MOC S. Sebzda (PSU) and A. Tohuvavohu (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 180613A 156 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 22769). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 22773) 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 u_FC 156 405 246 >20.4 v 461 24234 1434 >20.9 b 411 13230 1022 >99.0 u 156 18973 2109 >21.8 w1 510 18472 2212 >21.2 m2 486 24474 1627 >21.0 w2 1036 23321 1318 >20.1 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.09 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22820 SUBJECT: GRB 180613A: Afterglow confirmation and added photometry DATE: 18/06/21 14:47:01 GMT FROM: Christina Thoene at IAA-CSIC C.C. Thoene (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), N.R. Tanvir (Univ. of Leicester), D.A. Kann, L. Izzo (both HETH/IAA-CSIC), J.P.U. Fynbo (DAWN/NBI) and D.B. Malesani (DAWN/NBI, DARK/NBI) report on behalf of the Stargate consortium: We re-observed the field of GRB 180613A (Tohuvavohu et al., GCN 22769) with HAWK-I/VLT on 14 June 2018 at 23:37 UT (32.02 hr after the burst). The observation consisted of a combined exposure of 36 min in the J-band. The seeing of this observation was worse than during the first epoch (Thoene et al., GCN 22775) with an average value of 0.8", but the exposure time was significantly longer, allowing us to reach a deeper limit. In this second epoch we do not detect any more the source found by Thoene et al. (GCN 22775) down to a 3-sigma limit of J(Vega) > 24.2 mag. This implies that the source has faded, confirming that this source was indeed the afterglow of GRB 180613A. We also revise and provide the full photometry of our first HAWK-I epoch (GCN 22775, Thoene et al.) and obtain the following values: J(Vega)=23.24+/-0.26 or J(AB)=24.15+/-0.26 H(Vega)=22.23+/-0.22 or H(AB)=23.62+/-0.22 Ks(Vega)=21.04+/-0.27 or Ks(AB)=22.89+/-0.27 These values result in an IR spectral slope of 2.02 +/- 0.64, which would indicate a significant amount of extinction, explaining the faintness of the afterglow. Due to the lack of further data, we are not able to draw any definite conclusions in this matter. We acknowledge the continued excellent support from the ESO staff, in particular Frederic Vogt, Ivan Aranda and Eleonora Sani. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22841 SUBJECT: GRB 180613A: LCO Afterglow detection DATE: 18/06/25 11:26:35 GMT FROM: Antonino Cucchiara at UVI A. Cucchiara, D. Morris (U. Virgin Islands), C. Guidorzi, R. Martone (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), report report on behalf of a larger collaboration: "On June 13.84 UT (T_0 +4.5 hours) we began observing the center of the field of GRB 180613A (Tohuvavohu et al. GCN 22769, Beardmore et al. GCN 22773) using the Las Cumbres Observatory 1m telescope located South Africa Astronomical Observatory. We performed a series of 5x120s observations in SDSS-i' and SDSS-r' band for a total of 20 minutes on sky. In the full median stacked i'-band images we clearly identified the NIR counterpart reported by Thoene et al. (GCN #2275, #22820). This object is also marginally detected in our r' band stack. We estimate the following brightness for the optical counterpart: i' = 19.3 +- 0.6 We caution the usage of this measurement due to the high sky background near the GRB location caused by the presence of the nearby by a nearby 5.6 mag star (Schady et al. GCN #22777). This magnitude is calibrated against nearby UCAC4 sources, and is not corrected for Galactic extinction."