//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11473 SUBJECT: GRB 101219B: Swift detection of a burst with an optical afterglow DATE: 10/12/19 16:52:57 GMT FROM: Scott Barthelmy at NASA/GSFC J. M. Gelbord (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), M. M. Chester (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 16:27:53 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 101219B (trigger=440635). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 12.257, -34.532 which is RA(J2000) = 00h 49m 02s Dec(J2000) = -34d 31' 53" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). This is an image trigger so as is typical, the BAT lightcurve does not show anything. The XRT began observing the field at 16:30:19.8 UT, 146.3 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 12.2306, -34.5662 which is equivalent to: RA(J2000) = 00h 48m 55.34s Dec(J2000) = -34d 33' 58.3" with an uncertainty of 5.6 arcseconds (radius, 90% containment). This location is 145 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. UVOT took a finding chart exposure of 150 seconds with the White filter starting 156 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 00:48:55.35 = 12.23061 DEC(J2000) = -34:33:59.5 = -34.56652 with a 90%-confidence error radius of about 0.62 arc sec. This position is 1.2 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.84 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. Burst Advocate for this burst is J. M. Gelbord (jgelbord AT astro.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: 11475 SUBJECT: GRB 101219B: Swift-BAT refined analysis DATE: 10/12/19 21:59:06 GMT FROM: Scott Barthelmy at NASA/GSFC J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), N. Gehrels (GSFC), J. M. Gelbord (PSU), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+766 sec from recent telemetry downlinks, we report further analysis of BAT GRB 101219B (trigger #440635) (Gelbord, et al., GCN Circ. 11473). The BAT ground-calculated position is RA, Dec = 12.259, -34.556 deg which is RA(J2000) = 00h 49m 01.9s Dec(J2000) = -34d 33' 21.6" with an uncertainty of 3.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 7%. The mask-weighted light curve shows a broad peak starting at ~T+20 sec and ending at ~T+60 sec. However, given that there was a pre-planned slew ending just before T_zero, we can not rule out that was actvitity before this source came into the BAT FoV. T90 (15-350 keV) is 34 +- 5 sec (estimated error including systematics). The time-averaged spectrum from T+10 to T+60 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.56 +- 0.16. The fluence in the 15-150 keV band is 2.1 +- 0.4 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+26.84 sec in the 15-150 keV band is 0.6 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11477 SUBJECT: GRB 101219B: Fermi GBM observation DATE: 10/12/20 03:12:52 GMT FROM: Alexander van der Horst at NASA/MSFC A.J. van der Horst (USRA) reports on behalf of the Fermi GBM Team: "At 16:28:13.12 UT on 19 December 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 101219B (trigger 314468895 / 101219686), which was also detected by the Swift/BAT (GCN 11473). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 59 degrees. The GBM light curve consists of one peak with a duration (T90) of 51 +/- 2 s (50-300 keV). The time-averaged spectrum from T0-4.1 s to T0+47.1 s is best fit by a Band function with Epeak = 70 +/- 8 keV, alpha = 0.33 +/- 0.36, and beta = -2.12 +/- 0.12. The event fluence (10-1000 keV) in this time interval is (5.5 +/- 0.4)E-6 erg/cm^2. The 1-sec peak photon flux measured starting from T0+5.6 s in the 10-1000 keV band is 2.0 +/- 0.2 ph/s/cm^2. The temporal and spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11478 SUBJECT: GRB 101219B: GROND Detection of the Optical/NIR Afterglow DATE: 10/12/20 03:48:24 GMT FROM: Felipe Olivares Estay at MPE F. Olivares E. (MPE Garching), A. Rossi (TLS Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 101219B (Swift trigger 440635; Gelbord et al., GCN #11473) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla Observatory (Chile). Observations started during twilight at 00:33 UT on December 20, 8.1 hours after the GRB trigger, and were performed at an average seeing of 1" and an average airmass of 1.05. We confirm the optical afterglow candidate reported by Gelbord et al.(GCN #11473). The afterglow faded, however, it is well detected in all seven GROND optical/NIR bands. Based on 141 s of total exposure in g'r'i'z' and 240 s in JHK, taken at 00:36 UT mid-time, we estimate preliminary magnitudes (all in the AB system) of: g' = 20.4 +/- 0.1 r' = 20.0 +/- 0.1 i' = 20.0 +/- 0.2 z' = 19.6 +/- 0.1 J = 19.2 +/- 0.1 H = 18.8 +/- 0.1 and K = 18.6 +/- 0.1 A second epoch was obtained at 03:10 UT mid-time, with total exposure time of 1500 s in in g'r'i'z' and 1200 s seconds in JHK. The afterglow has faded by ~0.3 mag in the r' and J bands, which yields a temporal decay index of alpha = 1.0 between our two epochs. Given magnitudes are calibrated against GROND zero points and 2MASS field stars. The error in the optical bands is dominated by the zero-point uncertainty. Magnitudes are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E(B-V)=0.02 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11480 SUBJECT: GRB 101219B: Enhanced Swift-XRT position DATE: 10/12/20 11:56:31 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 2429 s of XRT Photon Counting mode data and 4 UVOT images for GRB 101219B, 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 = 12.23064, -34.56688 which is equivalent to: RA (J2000): 00h 48m 55.35s Dec (J2000): -34d 34' 00.8" with an uncertainty of 1.6 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: 11481 SUBJECT: GRB 101219B: Swift-XRT refined Analysis DATE: 10/12/20 16:57:06 GMT FROM: Jonathan Gelbord at PSU/Swift J.M. Gelbord (PSU) reports on behalf of the Swift-XRT team: We have analysed 17 ks of XRT data for GRB 101219B (Gelbord et al. GCN Circ. 11473), from 136 s to 65.2 ks after the BAT trigger. The data comprise 415 s in Windowed Timing (WT) mode (the first 9 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 Beardmore et al. (GCN. Circ 11480). The light curve (from T0+425 s) can be modelled with a series of power-law decays. The decay from T+425 s is steep, with an index of alpha=4.16 (+2.3, -0.50). At T+638 s the decay flattens to an alpha of 2.35 (+0.31, -0.46). Another break at T+4.7 ks is followed by a flatter decay of alpha = 0.23 (+/-0.15). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.68 (+/- 0.04). The best-fitting absorption column is consistent with the Galactic value of 3.14 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 1.69 (+0.12, -0.11) 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 4.1 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.1 (+0.9, -3.1) x 10^20 cm^-2 Galactic foreground: 3.14 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.69 (+0.12, -0.11) If the light curve continues to decay with a power-law decay index of 0.23, the count rate at T+24 hours will be 0.0060 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x 10^-13 (1.3 x 10^-13) erg cm^-2 s^-1. The count rate at T+48 hours would be 0.0051 count s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00440635. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11482 SUBJECT: GRB 101219B: Swift/UVOT refined analysis DATE: 10/12/21 00:09:32 GMT FROM: Paul Kuin at MSSL N.P.M. Kuin (MSSL/UCL) and J.M. Gelbord (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 101219B 156 s after the BAT trigger (Gelbord et al., GCN Circ. 11473). The optical afterglow is at 7 arcsec distance of a 16th magnitude star. Special care has been taken to subtract the estimated contribution of the neghboring star. The data suggest that after an initial brightening, there was a dimming around T+550s followed by a second brightening. Preliminary magnitudes of the GRB, using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) exposure and some selected subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag Mag_err white_FC 156 306 147.4 17.87 0.06 white 768 788 19.5 17.59 0.10 white 6686 6886 196.6 18.58 0.06 v 820 840 19.5 17.55 0.27 v 7097 7296 196.6 18.39 0.15 b 570 590 19.5 18.79 0.30 b 744 764 19.4 18.00 0.19 u 718 738 19.5 17.25 0.18 u 1298 1318 19.5 17.26 0.18 uvw1 1446 1465 19.4 17.43 0.28 uvw1 16352 16861 501 18.40 0.11 uvm2 7301 7392 89.6 18.15 0.24 uvm2 51175 52075 856 19.54 0.16 uvw2 6892 7092 197 18.04 0.13 uvw2 56901 57801 886 20.21 0.20 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11516 SUBJECT: GRB 101219B: After 2 weeks still detected by Swift/UVOT DATE: 11/01/03 23:31:29 GMT FROM: Jonathan Gelbord at PSU/Swift N.P.M. Kuin (MSSL/UCL) and J.M. Gelbord (PSU) report on behalf of the Swift/UVOT team: As reported earlier (Gelbord et al., GCN Circ. 11473; Kuin et al., GCN Circ. 11482), Swift/UVOT observations of GRB 101219B detected an optical afterglow in all its bands with initial magnitudes of about 18 mag. The optical afterglow has been unusually slow to decay, and is around 23 mag at present in the u and uv bands. The UVOT has obtained a good light curve in all bands up to about 300ks, with continuing detections through 1000ks in u, uvw1, uvm2, and uvw2 (v and b measurements after 300ks are significantly affected by the PSF wings of a B = 15.5 mag star located 7 arcsec to the SW). The light curve still appears to be decaying and there is some indication that this decay may not be smooth. GRB 101219B is further interesting because the UVOT light curve exhibits an early decay to about 600 seconds after the trigger time T, after which a second brightness rise to a maximum around T+850s occurs. A corresponding break is found in the X-ray light curve, in that the decay observed by XRT flattens approximately at T+700s. The only constraint on the redshift of this burst is an upper limit around 1.5 implied by the detection in uvw2, as there have not been any spectroscopic observations announced to date. However, if this burst is bright because it is close, then we might detect a supernova bump in the coming days. We consider this an interesting burst and would like to bring this to the attention of the community as an opportunity for further observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11549 SUBJECT: GRB 101219b. Possible radio afterglow detection. DATE: 11/01/10 08:26:41 GMT FROM: Dale A. Frail at NRAO Dale A. Frail (NRAO) reports on behalf of a larger collaboration: "We responded to a request (GCN#11516) for further observations of the long-lived optical afterglow of GRB 101219B. The Expanded Very Large Array (EVLA) observed a field toward this GRB (GCN#s 11473, 11482) on 2011 January 7.03 UT at a center frequency of 8.46 GHz. In a preliminary reduction of the data, we detect a weak radio source (Flux=71+/-15 uJy) at RA(J2000)=00:48:55.40 (+/-0.01) and Dec(J2000)=-34:34:00.1 (+/-0.7) that may be the afterglow of GRB 101219B. No further observations are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11575 SUBJECT: GRB 101219B: Likely the GRB host emission dominates now in the uvw2 filter DATE: 11/01/17 19:14:00 GMT FROM: Paul Kuin at MSSL N.P.M. Kuin (MSSL/UCL) and J.M. Gelbord (PSU) report on behalf of the Swift/UVOT team: Observations of GRB 101219B from 0.86Ms to 2.45Ms after the BAT trigger (T) continued in the u and uvw2 filter. The uvw2 light curve has been flat since T+1Ms. The late time uvw2 image obtained by summing the late time data in uvw2 shows that the likely host is offset from the GRB position by 1.2" with an estimated distance error (90% confidence) of 0.5". The host position is: RA = 00h 48m 54.37s Dec = -34d 33m 58.3s (J2000), which is (12.23069, -34.56620) in decimal degrees. The host magnitude is uvw2 = 23.4 +/- 0.3, which corresponds to a flux density at 1.477 x 10^15 Hz of (3.4 +/- 1.0)x10^(-4) mJy. In the u band (1.477 x 10^15 Hz) the observations terminated earlier than the in the uvw2. However, the u band data obtained between T+0.86Ms and T+1.8Ms give a 3-sigma upper limit of u > 23.3 with a corresponding flux density < 6.4 x 10^(-4) mJy. Observation in the uvw2 filter limits the redshift z < 1.4. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11576 SUBJECT: GRB 101219B: correction DATE: 11/01/17 20:59:43 GMT FROM: Paul Kuin at MSSL N.P.M. Kuin (MSSL/UCL) reports on behalf of the Swift/UVOT Team A typographical error slipped into the sexagesimal position given for the possible host in GCN 11575. The position should read: RA = 00h 48m 55.37s DEC = -34d 33m 58.3s (J2000) The position given in degrees was correct. Thanks go to Daniele Malesani for pointing this out. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11578 SUBJECT: GRB 101219B: GROND detection of a SN signature DATE: 11/01/19 16:57:31 GMT FROM: Felipe Olivares Estay at MPE F. Olivares E., P. Schady, T. Kruehler, J. Greiner (all MPE Garching), S. Klose, and D. A. Kann (Tautenburg Observatory) report on behalf of the GROND team: GROND continues to observe the field of the Swift GRB 101219B (Gelbord et al., GCN #11473) simultaneously in g'r'i'z'JHK. The light curve of the optical transient associated with this GRB (Olivares E. et al., GCN #11478, Kuin & Gelbord, GCNs 11482, 11516, 11575, 11576) started as a single power-law decay, but flattens at around day five at a preliminary AB magnitude of r' ~ 22.7. In addition there is a clear color change associated with the flattening. Starting at day 15, the light curve again decreases in all optical bands to a magnitude of r' ~ 23.7 at 27 days after the burst. This light curve shape is typical for GRB/SN events (e.g., Zeh et al. 2004, ApJ, 609, 952), and we hence interpret these observational features as signatures of an emerging and decaying supernova underlying the afterglow emission of GRB 101219B. Assuming a luminosity equal to that of SN 1998bw for the SN component, as well as negligible dust extinction along the line of sight, a conservative redshift range of 0.4 < z < 0.7 is derived for GRB 101219B. We note that the peak time rather short (around 14 days after burst, see Ferrero et al. 2006, A&A, 457, 857), which further suggests a low redshift for this GRB. We stress that at this stage, a possible host contribution and the SN component cannot be accurately disentangled and all results should be considered preliminary. Photometric and in particular spectroscopic observations with larger aperture telescopes aiming at the detection of the fading SN and/or host galaxy are highly encouraged. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 11579 SUBJECT: GRB 101219B: tentative redshift and spectroscopic supernova detection DATE: 11/01/19 18:33:31 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst Antonio de Ugarte Postigo (DARK/NBI), Paolo Goldoni (APC/Univ. Paris 7 and SAp/CEA), Bo Milvang-Jensen, Daniele Malesani, Martin Sparre, Johan P.U. Fynbo, Giorgos Leloudas (DARK/NBI), Stefano Covino (INAF/OABr), Hector Flores (GEPI/Obs. de Paris), Valerio D'Elia (ASI/ASDC and INAF/Roma), Andrew Levan (Univ. Warwick), report on behalf of the X-shooter GTO GRB collaboration: We observed the afterglow of GRB 101219B (Gelbord et al., GCN 11473) with the X-shooter spectrograph mounted on the ESO-VLT UT2. Observations were taken on two epochs, 2010 Dec 20.17 and 2011 Jan 5.09 UT (11.6 hr and 16.4 days after the burst, respectively). Exposure times were 80 and 120 min, respectively. In the first-epoch spectrum, the afterglow is detected over the full spectral range from about 3200 to 22,000 AA. A careful analysis provides a tentative redshift z=0.5519 based on detection of weak Mg II and Mg I. No other clear features can be found at the same redshift either in absorption or emission. The second-epoch spectrum was taken 16.4 days after the GRB, which corresponds to 10.6 days in the rest frame at z=0.55. The continuum is again detected, over the wavelength range 3500 to 22,000 AA, and is substantially redder. No narrow emission lines can be distinguished, but broad SN-like undulations are apparent, particularly around 8000 AA. We carried out a comparison of our spectrum with those of SN 1998bw (Patat et al. 2001, ApJ, 555, 900) transformed at various redshifts. We find a convincing match at z~0.55 after comparing with a spectrum taken on 1998 May 4 (i.e., 12 days after the GRB). The observed flux is consistent assuming a roughly equal contribution from a SN as bright as SN 1998bw and an underlying host galaxy. The match of the spectral shape, brightness, and spectral epoch together strenghten both the redshift determination and the existence of a SN associated with GRB 101219B. Our findings are in good agreement with the GROND observations reported by Olivares et al. (GCN 11578). Further observations are planned. We acknowledge the assistence of the ESO observing staff at Paranal, in particular Dimitri Gadotti, Leonel Rivas, Thomas Rivinius, Maja Vuckovic, and Thomas Szeifert.