//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24553 SUBJECT: GRB 190515B: Swift detection of a burst DATE: 19/05/15 16:17:18 GMT FROM: Michael Moss at George Washington U M. J. Moss (George Washington University), C. Gronwall (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 16:04:21 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 190515B (trigger=903845). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 98.840, +52.295 which is RA(J2000) = 06h 35m 22s Dec(J2000) = +52d 17' 41" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 20 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 16:05:43.7 UT, 82.4 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 98.84892, 52.31725 which is equivalent to: RA(J2000) = 06h 35m 23.74s Dec(J2000) = +52d 19' 02.1" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 82 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. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.27 x 10^21 cm^-2 (Willingale et al. 2013). The initial flux in the 2.5 s image was 7.78e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 92 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 84% 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 expected extinction corresponding to E(B-V) of 0.09. Burst Advocate for this burst is M. J. Moss (mikejmoss3 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/) [GCN OPS NOTE(15may19): Per author's request, the GRB name "190515A" was changed to "190515B" in the Subject lines in the first paragraph.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24554 SUBJECT: GRB 190515B: Prompt enhanced Swift-XRT position DATE: 19/05/15 16:35:25 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 190515B, we find an enhanced XRT position of the afterglow: RA, Dec: 98.8489, 52.3168 which is equivalent to: RA (J2000) = 06 35 23.73 Dec (J2000) = +52 19 00.4 with an uncertainty of 2.2 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/903845. 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. [GCN OPS NOTE(15may19): Per author's request, the GRB name was changed from "190515A" to "190515B" in the Subject line and the first sentence.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24555 SUBJECT: Correction to GRB name for Swift trigger 903845 DATE: 19/05/15 18:40:04 GMT FROM: Michael Moss at George Washington U M. J. Moss (GWU) reports on behalf of the Swift team: The GRB name reported in M. J. Moss et al. GCN Circ. #24553 (Swift trigger number: 903845) should be GRB 190515B. We apologize for any confusion caused. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24556 SUBJECT: GRB 190515B: Kitab Observatory optical upper limit DATE: 19/05/15 18:43:38 GMT FROM: Alexei Pozanenko at IKI, Moscow S. Belkin (IKI), A. Novichonok (KIAM), A. Pozanenko (IKI), E. Mazaeva (IKI), A. Volnova (IKI), I. Molotov (KIAM) report on behalf of larger IKI GRB FuN collaboration: We observed the field of the Swift GRB 190515B (Moss et al., GCN 24553) with RC-36 0.36-m telescope of Kitab Observatory starting on May 15 (UT) 16:13:02 in Clear filter. We do not find any optical source neither in the first image, nor in a stacked image within prompt enhanced Swift-XRT position (Evans et al., GCN 24554). Preliminary photometry of the field is following. Date UT start t-T0 Filter Exp. OT Err. UL(3sigma) (mid, days) (s) 2019-05-15 16:13:02 0.00655 CR 1*90 n/d n/d 18.6 2019-05-15 16:13:02 0.02686 CR 40*90 n/d n/d 20.3 The photometry is based on the nearby USNO-B1 (R2) star: USNO-B1.0_id R2 1422-0205150 15.02 The closest object which is not presented in any catalogs marginally detected in our stacked image has coordinates (J2000) 06:35:24.07 +52:19:12.4 with uncertainty of 1 arcsec in both coordinates and brightness of 20.4m (S/N =2). The position of the object is 12 arcsec apart from the the center of prompt enhanced Swift-XRT position (Evans et al., GCN 24554). At this time we cannot say about variability of the object. [GCN OPS NOTE(15may19): The GRB anme "190515A" was changed to "190515B" in the Subject line and in the first sentence.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24557 SUBJECT: GRB 190515B: Enhanced Swift-XRT position DATE: 19/05/15 19:51:47 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 611 s of XRT Photon Counting mode data and 1 UVOT images for GRB 190515B, 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 = 98.84772, +52.31665 which is equivalent to: RA (J2000): 06h 35m 23.45s Dec (J2000): +52d 18' 59.9" with an uncertainty of 2.3 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: 24558 SUBJECT: GRB 190515B: Optical observations from OSN DATE: 19/05/15 22:22:55 GMT FROM: Antonio de Ugarte Postigo at IAA-CSIC A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), M. Blazek, L. Izzo, C.C. Thoene, D.A. Kann, K. Bensch (all HETH/IAA-CSIC), A. Sota (IAA-CSIC) report: We observed the field of GRB 190515B (Moss et al. GCN 24553) with the 1.5m OSN telescope, at Sierra Nevada Observatory (Granada, Spain). The observation started at 21:13 UT (5.15 hr after the burst) when clouds over the observatory allowed, at an airmass of 2, and consisted of 3x300s exposures in I-band. No new object is detected within the refined XRT error circle (Osborne et al. GCN 24557) down to a 3-sigma limit of I(AB) = 20.5 mag, as compared to stars of the PanSTARRS catalogue. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24561 SUBJECT: GRB 190515B: Swift-XRT refined Analysis DATE: 19/05/16 02:38:48 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore (U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A. Tohuvavohu (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team: We have analysed 6.3 ks of XRT data for GRB 190515B, from 88 s to 27.5 ks after the BAT trigger. The data comprise 66 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 24557). The light curve can be modelled with an initial power-law decay with an index of alpha=3.85 (+0.26, -0.23), followed by a break at T+296 s to an alpha of 0.38 (+0.11, -0.12). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 3.26 (+0.33, -0.30). The best-fitting absorption column is 2.1 (+0.6, -0.5) x 10^21 cm^-2, in excess of the Galactic value of 1.3 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.06 (+0.24, -0.15) and a best-fitting absorption column consistent with the Galactic value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.3 (+0.6, -0.0) x 10^21 cm^-2 Galactic foreground: 1.3 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 2.06 (+0.24, -0.15) If the light curve continues to decay with a power-law decay index of 0.38, the count rate at T+24 hours will be 0.027 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.0 x 10^-13 (1.2 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/00903845. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24564 SUBJECT: GRB 190515B: Swift-BAT refined analysis DATE: 19/05/16 13:28:03 GMT FROM: Amy Lien at GSFC H. A. Krimm (NSF), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), M. J. Moss (GWU), 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+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 190515B (trigger #903845) (Moss et al., GCN Circ. 24553). The BAT ground-calculated position is RA, Dec = 98.826, 52.322 deg which is RA(J2000) = 06h 35m 18.3s Dec(J2000) = +52d 19' 17.6" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 67%. The mask-weighted light curve shows a single-pulse structure that starts at ~T-30 s, peaks at ~T0, and ends at ~T+30 s. T90 (15-350 keV) is 46.4 +- 12.3 sec (estimated error including systematics). The time-averaged spectrum from T-30.84 to T+31.02 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.74 +- 0.15. The fluence in the 15-150 keV band is 1.6 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.39 sec in the 15-150 keV band is 1.1 +- 0.2 ph/cm2/sec. 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/903845/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24567 SUBJECT: GRB 190515B: BOOTES-4/MET and 2.2m CAHA optical limits DATE: 19/05/17 03:26:28 GMT FROM: Alberto J. Castro-Tirado at IAA-CSIC Y.-D. Hu, X.-Y. Li, E. Fernandez-Garcia, A. Ayala, A. J. Castro-Tirado (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), S. Guziy (Univ. of Nikolaev), D. Xiong, Y. Fan, X. Zhao, J. Bai, C. Wang, Y. Xin, J. Mao (Yunnan Nacional Astronomical Observatory), A. Fernandez and I. Hermelo (CAHA), on behalf of a larger collaboration, report: Following the detection of GRB 190515B by Swift (Moss et al. GCNC 24553), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) automatically responded gathering 9 frames (g’ filter, 30s exposures) starting at 16:10:44UT (0.11 hr after trigger). In addition, 23 frames at the 2.2m Calar Alto telescope equipped with CAFOS (I-band, 120s exposures) were taken starting at 20:45:41 UT (4.69 h post burst). On the co-added images, no optical afterglow is found down to 18.9 mag (g-band) or 22.1 (I-band) respectively at the enhaced XRT position (Evans et al. GCNC 24554), in agreement with Belkin et al. (GCNC 24556) and de Ugarte Postigo et al. (GCNC 24558). Particularly the Calar Alto co-add I-band frame does not detect the marginal object reported in GCNC 24556. We thank the CAHA staff for excellent support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 24568 SUBJECT: GRB 190515B: Swift/UVOT Upper Limits DATE: 19/05/17 03:44:52 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and M. J. Moss (George Washington University) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 190515B 93 s after the BAT trigger (Moss et al., GCN Circ. 24553). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 24557) 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 93 242 147 >19.9 u_FC 305 555 246 >19.4 white 93 605 167 >20.0 v 636 4442 216 >18.9 b 561 754 39 >18.7 u 305 730 265 >19.5 w1 685 4722 88 >18.9 m2 661 4647 216 >19.6 w2 612 4237 216 >19.0 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).