//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15139 SUBJECT: GRB 130831A: Swift detection of a burst with an optical counterpart DATE: 13/08/31 13:21:11 GMT FROM: David Palmer at LANL L. M. Z. Hagen (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC), D. Grupe (PSU), J. A. Kennea (PSU), V. Mangano (PSU), F. E. Marshall (NASA/GSFC), C. J. Mountford (U Leicester), P. T. O'Brien (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), E. Troja (NASA/GSFC/UMCP) and B.-B. Zhang (UAH) report on behalf of the Swift Team: At 13:04:16 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130831A (trigger=568849). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 358.649, +29.448 which is RA(J2000) = 23h 54m 36s Dec(J2000) = +29d 26' 53" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 50 sec. The peak count rate was ~10000 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 13:06:22.3 UT, 125.8 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 358.62398, 29.42849 which is equivalent to: RA(J2000) = 23h 54m 29.76s Dec(J2000) = +29d 25' 42.6" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 105 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 consistent with the Galactic value of 4.80 x 10^20 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 8.87e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 250 seconds with the U filter starting 190 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 23:54:29.89 = 358.62453 DEC(J2000) = +29:25:46.2 = 29.42950 with a 90%-confidence error radius of about 0.74 arc sec. This position is 5.8 arc sec. from the center of the XRT error circle. The estimated magnitude is 14.56 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04. Burst Advocate for this burst is L. M. Z. Hagen (lea.zernow.hagen 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/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15140 SUBJECT: GRB 130831A: Faulkes Telescope North and South optical afterglow DATE: 13/08/31 13:38:30 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), A. Melandri (INAF-OAB) on behalf of a large collaboration report: The 2-m Faulkes Telescopes North and South automatically began observing GRB 130831A (Hagen et al. GCN Circ. 15139) on August 31 2013 at 13:09:01 UT (~4.7 min after the burst trigger). We clearly detect the fading optical afterglow reported by Swift/UVOT with R=14.1 +- 0.1 mag at 4.75 minutes since the BAT trigger time, calibrated against nearby USNOB-1 catalogue stars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15142 SUBJECT: GRB 130831A: Weihai optical observations DATE: 13/08/31 14:29:36 GMT FROM: Dong Xu at DARK/NBI D. Xu (DARK/NBI), C. M. Zhang, C. Cao, S. M. Hu (SDU) report: We observed the field of GRB 130831A (Hagen et al., GCN 15139) using the 1m telescope located in Weihai, Shandong Province, China, and 2x600s SDSS r'-band frames were obtained. The optical afterglow is well detected at the UVOT position in each of the two images with rather fast decaying rate. Following photometry is calibrated with nearby SDSS stars: Mag MagErr MeanTime(T-Ttrigger, hr) 14.35 0.04 0.3356 15.66 0.05 0.6575 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15143 SUBJECT: GRB 130831A: MITSuME Akeno Optical observation DATE: 13/08/31 15:03:11 GMT FROM: Taketoshi Yoshii at Tokyo Tech T. Yoshii, K. Ito, Y. Saito, Y. Yano, R. Usui, Y. Tachibana, S. Kurita, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 130831A (L. M. Z. Hagen et al., GCNC 15139) with the optical three color (g, Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. And we continue observing . The observation started on 2013-08-31 13:06:14 UT ( 118 sec after the burst). And we detected the previously reported afterglow . But weather condition was not so good. The measured magnitudes were listed below. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic ------------------------------------------------------------------------------------------------------------------------------ ~118 13:07:41 300 15.40+/-0.23 15.16+/-0.33 analyzing ------------------------------------------------------------------------------------------------------------------------------ (The photon flux were calibrated against GSC2.3 catalog.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15144 SUBJECT: GRB 130831A: Gemini-North Redshift DATE: 13/08/31 15:37:32 GMT FROM: Antonino Cucchiara at UCSC/UCO Lick A. Cucchiara (UCSC/UCO Lick Observatory), D. Perley (Caltech) report on behalf of a larger collaboration: "We observed the afterglow of GRB 130831A (Hagen et al. GCN 15139, Guidorzi et al. GCN 15140) with the GMOS spectrograph on Gemini-North, beginning approximately 50 min after the BAT trigger. We obtained 2x900s exposure spectra under exquisite conditions using the B600 grism, covering the 3860-6649 Angstrom wavelength range. In our preliminary analysis we detect MgII2796,2803 doublet and MgI2853 absorption lines at z=0.4791. No other strong features are detected in absorption or in emission, therefore we suggest this as the redshift of GRB 130831A. We thank the Gemini-N staff, in particular Adam Smith and Anthony Matulonis, for their support." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15145 SUBJECT: Konus-Wind observation of GRB 130831A DATE: 13/08/31 18:50:31 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The long-duration soft-spectrum GRB 130831A (Swift-BAT trigger 568849: Hagen, et al., GCN 15139) triggered Konus-Wind at T0=47062.044 s UT (13:04:22.044) The light curve shows a smooth pulse peaked at ~T0+1.6 s followed by a weaker emission till ~T0+35~s. The emission is seen up to ~6 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB130831_T47062/ As observed by Konus-Wind, the burst had a fluence of (7.6 ± 0.4)x10-6 erg/cm2, and a 64-ms peak flux, measured from T0+1.600 s, of (2.5 ± 0.3)x10-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum (measured from T0 to T0+24.832 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.61 ± 0.06, the high energy photon index beta = -3.3 ± 0.3, the peak energy Ep = 55 ± 4 keV, chi2 = 118/97 dof. The spectrum at the maximum count rate (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.51 ± 0.10, the high energy photon index beta = -2.8 ± 0.1, the peak energy Ep = 67 ± 4 keV, chi2 = 91/96 dof. Assuming Gemini-North redshift z=0.4791 (Cucchiara & Perley, GCN 15144), and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, and Omega_Lambda = 0.73, we estimate the following rest-frame parameters of GRB 130831A: the isotropic energy release E_iso is (4.6 ± 0.2)x10^51 erg, the peak luminosity (L_iso)_max is (2.7 ± 0.3)x10^51 erg/s, and the rest-frame peak energy Ep,i = (81 ± 6) keV All the quoted results are preliminary. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15146 SUBJECT: GRB 130831A : Xinglong 60cm optical observation DATE: 13/08/31 19:39:25 GMT FROM: L.P. Xin at NAOC L. P. Xin, X. H. Han, Y. L. Qiu, J. Y. Wei, J. Wang, J. S. Deng and C. Wu on behalf of EAFON report: We began to observe GRB 130831A (Hagen et al. GCN 15139) with Xinglong 60cm telescope at 15:42:00 (UT), about 2.7 hours after the burst. A series of white and R-band images were obtained. The OT reported by (Hagen et al. GCN 15139, Guidorzi et al. GCN 15140, Xu et al. GCN 15142; Yoshii et al. GCN 15143, Cucchiara et al. GCN 15144) was detected in all images. The brightness of this OT was about R=16.6 mag at 2.7 hours after the burst, calibrated by USNO B1.0 R2 mag. This message may be cited.//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15147 SUBJECT: GRB 130831A: Enhanced Swift-XRT position DATE: 13/08/31 20:40:42 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 2474 s of XRT Photon Counting mode data and 3 UVOT images for GRB 130831A, 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 = 358.62461, +29.42990 which is equivalent to: RA (J2000): 23h 54m 29.91s Dec (J2000): +29d 25' 47.6" with an uncertainty of 1.7 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: 15148 SUBJECT: GRB 130831A: Skynet/PROMPT-SSO detections DATE: 13/08/31 21:08:52 GMT FROM: Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet A. Trotter, J. Haislip, A. LaCluyze, J. Moore, N. Frank, D. Reichart, T. Berger, H. T. Cromartie, R. Egger, A. Foster, K. Ivarsen, M. Maples, M. Nysewander, and J. A. Crain report: Skynet observed the Swift/BAT localization of GRB 130831A (Hagen et al., GCN 15139, Swift trigger #568849) with four 17" telescopes of the newly-commissioned PROMPT array at Siding Spring Observatory, NSW, Australia. Starting at 2013-08-31, 13:39 UT and continuing until 17:41 UT (t=35.5m-4.65h post-trigger), it took 615 80-s exposures in the BVRI bands. We detect a bright fading afterglow in all four bands at RA 23:54:29.8, Dec 29:25:46.4 (J2000.0), within the error circle of the Enhanced Swift-XRT localization (Evans et al., GCN 15147). A preliminary light curve is at: http://skynet.unc.edu/grb/grb130831a.png Magnitudes are in the Vega system, calibrated to 6 APASS stars in the field, and have not been corrected for the modest expected line-of-sight Milky Way dust extinction E(B-V)=0.046 (Schlegel et al. 1998). Skynet observations are ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15150 SUBJECT: GRB 130831A: Montarrenti Observatory optical observations DATE: 13/09/01 01:07:49 GMT FROM: Simone Leonini at Monarrenti Obs Simone Leonini, G. Guerrini, P. Rosi and L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy) report: We observed the optical afterglow of GRB 130831A (Swift trigger 568849, Hagen et al., GCN Circ. 15139) and slow fading over the four hours span of observations with the automatic 0.53m RC telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88). The observations were started at 2013-08-31 20:18:04 UT (approximately 7 hours post-burst) and continued to 00:29:36 UT on 2013-09-01 stacking 2 unfiltered CCD exposures of 60s for each run. The OT was detected in all frames. The resulting time-series are as follows: 2013 Aug 31.84588 UT R=18.22 +/- 0.21 2013 Aug 31.90427 UT R=18.55 +/- 0.21 2013 Aug 31.94019 UT R=18.47 +/- 0.22 2013 Aug 31.96977 UT R=18.63 +/- 0.23 2013 Aug 31.99955 UT R=18.95 +/- 0.22 2013 Sep 01.02056 UT R=19.09 +/- 0.21 Magnitudes were obtained using Astrometrica software using USNO-B1 catalogue for positions and photometry. An ensemble between 38 and 66 stars were used for the magnitude comparison. The position of the GRB (within the error box given by Swift) is the following: RA (J2000.0) 23h 54m 29.90s +/-0.13 Decl. (J2000.0) +29° 25' 46.8" +/-0.14 The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15151 SUBJECT: GRB 130831A: Swift-XRT refined Analysis DATE: 13/09/01 01:21:03 GMT FROM: Phil Evans at U of Leicester B. Sbarufatti (INAF-OAB/PSU), V. Mangano (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and L.M.Z. Hagen report on behalf of the Swift-XRT team: We have analysed 6.2 ks of XRT data for GRB 130831A (Hagen et al. GCN Circ. 15139), from 115 s to 23.9 ks after the BAT trigger. The data comprise 73 s in Windowed Timing (WT) mode (the first 10 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 Evans et al. (GCN. Circ 15147). The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=3.0 (+0.4, -0.6). At T+239 s the decay flattens to an alpha of -0.1 (+0.3, -0.6) before breaking again at T+783 s to a final decay with index alpha=1.09 (+0.09, -0.07). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.53 (+0.12, -0.11). The best-fitting absorption column is consistent with the Galactic value of 4.8 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 1.78 (+0.12, -0.08) and a best-fitting absorption column of 5.2 (+2.8, -0.4) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (4.4 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 5.2 (+2.8, -0.4) x 10^20 cm^-2 Galactic foreground: 4.8 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.78 (+0.12, -0.08) If the light curve continues to decay with a power-law decay index of 1.09, the count rate at T+24 hours will be 0.024 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.5 x 10^-13 (1.1 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/00568849. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15152 SUBJECT: GRB 130831A: Optical Observations via Virtual Telescope DATE: 13/09/01 01:54:33 GMT FROM: Gianluca Masi at Bellatrix Astronomical Obs G. Masi (Ceccano, Italy) and F. Nocentini (Frosinone, Italy) report: On Sept 1.0599 2013 UT, we imaged the field around GRB 130831A (GCN 15139) remotely using the the 0.43m-f/6.8 robotic unit part of the Virtual Telescope robotic facility in Italy, about 12 hours after the burst. The source is visible on 300 seconds unfiltered CCD images following coordinates (J2000.0): R.A. = 23 54 29.89 Decl. +29 25 46.6 We also performed photometry, assuming R-mags from UCAC-4 for the stars in the field, getting an estimate for the magnitude of 19.1 (CR). Observations are ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15153 SUBJECT: GRB 130831A: optical observations DATE: 13/09/01 01:56:19 GMT FROM: Luca Izzo at ICRA L. Izzo and L. D'Avino report: We have observed the optical afterglow of GRB 130831A using a 0.32m = f/9.3 Ritchey-Chretien telescope of the iTelescope network, at Siding = Spring =96 Australia. We have detected the afterglow in the R and V, but not in the B band. = After an ensemble photometry, using nearby SDSS stars, and correction = from SDSS to V and R filters, we have obtained the following = magnitudes: R =3D 15.58 +- 0.09 (78 min post-trigger =96 240s exposure) V =3D 16.89 +- 0.09 (92 min post-trigger =96 180 s exposure) The R-composite image can be seen at http://blacksabburst.files.wordpress.com/2013/08/r_median.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15155 SUBJECT: GRB 130831A, Swift-BAT refined analysis DATE: 13/09/01 04:15:22 GMT FROM: Tilan Ukwatta at MSU S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), L. M. Z. Hagen (PSU), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-61 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 130831A (trigger #568849) (Hagen, et al., GCN Circ. 130831A). The BAT ground-calculated position is RA, Dec = 358.635, 29.431 deg which is RA(J2000) = 23h 54m 32.4s Dec(J2000) = +29d 25' 51.4" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 28%. BAT mask-weighted light curve shows a bright peak starting from ~T-1 sec peaking around T+3 sec and ending at ~T+12 sec. Two more very weak emission can be seen around T+20 sec and T+32 sec. T90 (15-350 keV) is 32.5 +- 2.5 sec (estimated error including systematics). The time-averaged spectrum from T-1.86 to T+41.38 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.93 +- 0.05. The fluence in the 15-150 keV band is 6.5 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+2.30 sec in the 15-150 keV band is 13.6 +- 0.6 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/568849/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15156 SUBJECT: GRB 130831A: THO optical observation DATE: 13/09/01 06:48:23 GMT FROM: Veli-Pekka Hentunen at Taurus Hill Obs,A95 Veli-Pekka Hentunen, Markku Nissinen, Harri Vilokki and Tuomo Salmi (Taurus Hill Observatory, Varkaus, Finland) report: We have detected GRB 130831A optical afterglow at Taurus Hill Observatory A95 (Varkaus, Finland). We used 0.35m C-14 OTA telescope (f =3910 mm), NextGen 0.5X, Paramount ME and SBIG ST-8XME CCD camera. The observation was started 6.65 hours after the Swift trigger. Six unfiltered images with 600 sec exposure time were made. The afterglow was detected at following position RA 23 54 29.7 and DEC +29 25 46.6. The following magnitude was obtained from the observation using NOMAD1 1194-0619856 (R=16.240) as the comparison: Tmid(h)+T0 Filter Exp. time Mag Mag err. 7.218 unfiltered 6x600 18.01CR 0.08 A png preview of the observation showing the position of the afterglow is available at this URL: www.kassiopeia.net/wp-content/uploads/2013/09/GR130831A_comparison.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15159 SUBJECT: GRB 130831A: CARMA mm upper limit DATE: 13/09/01 16:58:42 GMT FROM: Ashley Zauderer at CfA B. A. Zauderer, T. Laskar , and E. Berger (Harvard) report on behalf of the CARMA Key Project, "A Millimeter View of the Transient Universe" and a larger collaboration: "We observed the position of the optically bright GRB 130831A (Hagen et al. GCN 15139; Xu et al. GCN 15142) with the Combined Array for Research in Millimeter Astronomy (CARMA) beginning 2013 September 1.30 (dt = 0.76 d). At a mean frequency of 90 GHz, in marginal weather conditions, we obtain a 3-sigma upper limit of 0.78 mJy. We thank the CARMA observers and staff for their support." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15161 SUBJECT: GRB 130831A: T100 observations DATE: 13/09/01 19:05:58 GMT FROM: Eda Sonbas at NASA/GSFC E. Sonbas (Adiyaman Univ.), U. Temiz (Cukurova Univ.), T. Guver (Sabanci Univ.), Z. Eker (Akdeniz Univ.), S. Kaynar (TUG), E. Gogus (Sabanci Univ.), H. Kirbiyik (TUG) report on behalf of a larger collaboration We observed the field of Swift GRB 130831A (Hagen et al. GCN#15139) with the 1.0 meter T100 telescope (TUBITAK National Observatory, Antalya - Turkey), starting August, 31; 18:27:23 UT (~ 5.4 hours after the trigger). Observations were carried out in the R filter under moderate weather conditions. We detected a new source in 300 s R band image at a position that is consistent with Swift/UVOT (Hagen et al. GCN#15139) Using USNO-B1 star USNO-B1 1193-0589854 (RA= 23:54:29.226, Dec= +29:23:08.41) in the field, the magnitude of the OT were estimated as; t-t0 (hr) exp.(s) filt mag err (+/-) 5.38 300 R 17.98 0.034 5.48 300 R 17.99 0.035 Further observations using the same filter are ongoing. We are grateful to the TUBITAK National Observatory staff for promptly scheduling the observations and their technical support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15162 SUBJECT: GRB 130831A: VLA Observations DATE: 13/09/01 21:36:31 GMT FROM: Tanmoy Laskar at Harvard U T. Laskar, A. Zauderer, and E. Berger (Harvard) report: "We observed the position of GRB 130831A (Hagen et al; GCN 15139) with the VLA beginning on 2013 September 1.19 UT (0.64 days after the burst). No significant radio emission is detected at the enhanced Swift-XRT position or the optical position, to a three-sigma upper limit of 38 uJy at 5.8 GHz and 71 uJy at 21.8 GHz." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15164 SUBJECT: GRB 130831A: Continued Skynet/PROMPT-SSO, PROMPT-CTIO and Yerkes-41 detections DATE: 13/09/02 01:57:04 GMT FROM: Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet A. Trotter, J. Haislip, D. Reichart, A. LaCluyze, J. Moore, N. Frank, V. Hoette, D. Harper, R. Kron, K. Cudworth, E. Struble, R. Russell, T. Berger, H. T. Cromartie, R. Egger, A. Foster, K. Ivarsen, M. Maples, M. Nysewander, and J. A. Crain report: Skynet continued observing the Swift-XRT localization of GRB 130831A (Hagen et al., GCN 15139, Swift trigger 568849) with the four 17" telescopes of the PROMPT array at Siding Spring Observatory, NSW, Australia, four 16" telescopes of the PROMPT array at Cerro Tololo, Chile, and the 41" telescope of Yerkes Observatory in Wisconsin, USA. Starting at 2013-08-31, 13:39 UT and continuing until 2013-09-01, 17:40 UT (t=35.5m-28.2h post-trigger), Skynet took a total of 2,227 exposures of 60-160s in the BVRI (PROMPT) and g'i' bands (Yerkes). As we reported in Trotter et al. (GCN 15148), we detect a bright fading afterglow in all bands at RA 23:54:29.8, Dec 29:25:46.4 (J2000.0), within the error circle of the Enhanced Swift-XRT localization (Evans et al., GCN 15147). We continue to detect a fading afterglow in stacked images, with R~20 mag at t~15h, and R~20.6 mag at t~25h. A preliminary light curve that includes our first-day PROMPT-CTIO and Yerkes data, and our second-day PROMPT-SSO data is at: http://skynet.unc.edu/grb/grb130831a_2.png BVRI magnitudes are in the Vega system, and g'i' magnitudes are in the AB system, calibrated to 3 APASS stars in the field. Photometry has not been corrected for the modest expected line-of-sight Milky Way dust extinction E(B-V)=0.046 (Schlegel et al. 1998). Skynet observations are ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15165 SUBJECT: GRB 130831A: RATIR Optical and NIR Observations DATE: 13/09/02 02:52:18 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 (UCSC), 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 GRB 130831A (Hagen, et al., GCN 15139) 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 2013/09 1.16 to 2013/09 1.49 UTC (14.65 to 22.73 hours after the BAT trigger), obtaining a total of 5.16 hours exposure in the r' and i' bands and 2.09 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-XRT error circle (Evans et al., GCN 15147), in comparison with SDSS DR9 and 2MASS, we obtain the following detections: r' 20.64 +/- 0.03 i' 20.38 +/- 0.03 Z 20.20 +/- 0.07 Y 19.69 +/- 0.07 J 19.87 +/- 0.09 H 19.88 +/- 0.14 These magnitudes are in the AB system and not corrected for Galactic extinction in the direction of the GRB. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15166 SUBJECT: GRB 130831A: Optical Observations via Virtual Telescope, follow-up DATE: 13/09/02 11:21:46 GMT FROM: Gianluca Masi at Bellatrix Astronomical Obs G. Masi (Ceccano, Italy) and F. Nocentini (Frosinone, Italy) report: On Sept 1.9197 2013 UT, we imaged the field around GRB 130831A (GCN 15139) remotely using the the 0.43m-f/6.8 robotic unit part of the Virtual Telescope robotic facility in Italy, about 33 hours after the burst. We co-added 12, 300-seconds unfiltered CCD images and detected the afterglow at the same position we gave in GCN 15152. We performed photometry, assuming R-mags from UCAC-4 for the stars in the field, getting an estimate for the magnitude of 20.7 (CR). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15167 SUBJECT: GRB 130831A: Montarrenti Observatory optical follow-up DATE: 13/09/02 12:43:02 GMT FROM: Simone Leonini at Monarrenti Obs Simone Leonini, G. Guerrini, P. Rosi and L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy) report: We continue to observe and detect the fading optical afterglow of GRB 130831A (Swift trigger 568849, Hagen et al., GCN Circ. 15139) with the automatic 0.53m RC telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88). We stacked 4 unfiltered CCD exposures of 60s each and we detect the very faint OT at the same position previously measured (GCN 15150) obtaining the following photometry at t~34h : 2013 Sep. 01.95733 UT R=20.46 +/- 0.24 Magnitudes were obtained using Astrometrica software using USNO-B1 catalogue for positions and photometry. An ensemble of 66 stars were used for the magnitude comparison. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15168 SUBJECT: GRB 130831A: Swift/UVOT Observations DATE: 13/09/02 14:17:51 GMT FROM: Margaret Chester at PSU M. M. Chester (PSU) and L.M.Z. Hagen (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130831A (Hagen et al., GCN Circ. 15139) 191 seconds after the BAT trigger. A source consistent with the enhanced XRT position (Evans et al., GCN Circ. 15147) is detected in the initial UVOT exposures. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposures and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag v 498 818 58 14.4 +/- 0.1 v 10802 11709 885 18.0 +/- 0.1 v 46801 47000 196 > 18.9 b 448 767 58 14.9 +/- 0.1 b 23522 23925 393 19.2 +/- 0.2 b 40193 41100 885 20.1 +/- 0.2 u_FC 191 441 246 14.6 +/- 0.1 u 572 742 39 13.9 +/- 0.1 u 16594 23517 1645 18.3 +/- 0.1 w1 548 849 40 13.9 +/- 0.1 w1 15688 16588 886 18.1 +/- 0.1 m2 673 843 39 13.6 +/- 0.1 m2 11714 12387 663 17.5 +/- 0.1 w2 474 494 19 14.8 +/- 0.1 w2 9896 10796 886 17.5 +/- 0.1 w2 41107 46795 1009 19.3 +/- 0.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15174 SUBJECT: GRB 130831A: JCMT SCUBA-2 sub-mm observation DATE: 13/09/04 02:01:33 GMT FROM: Ian Smith at Rice U I.A. Smith (Rice U.), R.P.J. Tilanus (Leiden Observatory), N.R. Tanvir (U. of Leicester), D.A. Frail (NRAO) report: We observed the location of GRB 130831A (Hagen et al., GCN Circ. 15139) using the SCUBA-2 sub-millimeter continuum camera on the James Clerk Maxwell Telescope. The observation started at 14:13 UT on 2013-08-31, corresponding to 69 minutes after the burst trigger. Exposures totaling 2.0 hours were made in good weather conditions. No source was detected, with a preliminary RMS of 1.4 mJy/beam at 850 microns and 13.7 mJy/beam at 450 microns. We thank Callie McNew for the prompt support of these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15179 SUBJECT: GRB 130831A: RATIR Optical and NIR Upper Limits DATE: 13/09/04 18:43:54 GMT FROM: Owen Littlejohns at Az State U Alan M. Watson (UNAM), Owen Littlejohns (ASU), Nat Butler (ASU), 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 (UCSC), Eleonora Troja (GSFC), 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 again observed the field of GRB 130831A (Hagen, et al., GCN 15139) 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 2013/09 4.32 to 2013/09 4.34 UTC (90.60 to 91.04 hours after the BAT trigger), obtaining a total of 0.36 hours exposure in the r' and i' bands and 0.15 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-XRT error circle (Evans et al., GCN 15147), in comparison with SDSS DR9 and 2MASS, we obtain the following upper limits (3-sigma): r' > 22.84 i' > 22.94 Z > 20.76 Y > 20.23 J > 20.09 H > 19.49 In comparison with earlier RATIR observations (Butler et al., GCN 15165) the source has faded by 2.2 magnitudes in the r' band and 2.6 magnitudes in the i' band. This implies a power-law decay steeper than t^-1.7. The upper limits obtained in the Z, Y, J, and H bands are also consistent with such a steep decay index. These magnitudes are in the AB system and not corrected for Galactic extinction in the direction of the GRB. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15185 SUBJECT: GRB 130831A: ISON-UAFO optical observations DATE: 13/09/07 23:20:51 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), A. Matkin (UAFO, ISON), A. Stepura (UAFO, ISON), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the afterglow (Hagen et al., GCN 15139; Guidorzi et al., GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with SANTEL-650 (0.65m) and VT-50 (0.5m) telescopes of UAFO/ISON-Ussuriysk observatory starting on Aug. 31 (UT) 13:14:32, i.e. 10.3 minutes after burst trigger. We took unfiltered images of 120s and 30s exposures ending observations at (UT) 19:20:53. In each initial frames we clearly detect afterglow. A preliminary photometry of the afterglow in the initial frames are following T_start T0+ Filter, Exposure, OT, OT_err (UT) (mid, d) (s) 2013-08-31T13:14:32 0.00782 none 120 13.86 0.02 2013-08-31T13:l6:40 0.00931 none 120 13.75 0.02 2013-08-31T13:18:49 0.01080 none 120 13.78 0.02 The photometry is based on reference stars SDSS-DR9, (R mag, transformation by Lupton 2005) N SDSS id R(Lupton)errR 1 J235443.71+292539.3 13.491 0.016 2 J235438.60+292547.3 14.136 0.015 3 J235423.64+292452.8 17.120 0.016 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15186 SUBJECT: GRB 130831A: optical observation in Gissar AO DATE: 13/09/07 23:43:47 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), N. Minikulov (Institute of Astrophysics), M.Gulyamov (Institute of Astrophysics), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the afterglow (Hagen et al., GCN 15139; Guidorzi et al., GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with AZT-8 (0.7m) telescope of Gissar observatory in R filter starting on Aug. 31 (UT) 17:47:54. A preliminary photometry of combined image is based on SDSS DR9 stars T_start T0+ Filter, Exposure, OT, OT_err (UT) (mid, d) (s) 2013-08-31T17:47:54 0.21932 R 57x60 18.28 0.04 Reference stars SDSS-DR9, (R mag, transformation by Lupton 2005) N SDSS id R(Lupton)errR 1 J235443.71+292539.3 13.491 0.016 2 J235438.60+292547.3 14.136 0.015 3 J235423.64+292452.8 17.120 0.016 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15188 SUBJECT: GRB 130831A: ISON-Kislovodsk optical observations DATE: 13/09/07 23:52:12 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), V. Linkov (ISON), K. Polyakov (ISON), D. Ivanov (ISON), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the afterglow (Hagen et al., GCN 15139; Guidorzi et al., GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with SANTEL-400AN telescope of ISON-Kislovodsk observatory starting on Aug. 31 (UT) 19:12:30. We took several unfiltered images. Preliminary photometry of combined images is following T_start T0+ Filter, Exposure, OT, OT_err (UT) (mid, d) (s) 2013-08-31T19:12:30 0.26113 none 840 18.32 0.08 2013-08-31T19:28:20 0.27212 none 840 18.44 0.10 2013-08-31T19:47:24 0.29470 none 1760 18.47 0.13 The photometry is based on reference stars SDSS-DR9, (R mag, transformation by Lupton 2005) N SDSS id R(Lupton)errR 1 J235443.71+292539.3 13.491 0.016 2 J235438.60+292547.3 14.136 0.015 3 J235423.64+292452.8 17.120 0.016 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15189 SUBJECT: GRB 130831A: optical observation in Chuguev AO DATE: 13/09/07 23:56:01 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), Yu. Krugly (IA KhNU), I. Slyusarev (IA KhNU), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the afterglow (Hagen et al., GCN 15139; Guidorzi et al., GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with AZT-8 (0.7m) telescope of Institute of Astronomy, Kharkiv National University in R filter starting on Sep. 01 (UT) 19:37:49. A preliminary photometry of combined images is based on SDSS DR9 stars T_start T0+ Filter, Exposure, OT, OT_err (UT) (mid, d) (s) 2013-09-01T19:37:49 1.29474 R 28x120 21.26 0.07 Reference stars SDSS-DR9, (R mag, transformation by Lupton 2005) N SDSS id R(Lupton)errR 1 J235443.71+292539.3 13.491 0.016 2 J235438.60+292547.3 14.136 0.015 3 J235423.64+292452.8 17.120 0.016 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15190 SUBJECT: GRB 130831A: Maidanak optical observations DATE: 13/09/08 00:17:41 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), A. Volnova (IKI), B. Hafizov (UBAI), O. Burhonov (UBAI) report on behalf of larger GRB follow-up collaboration: We observed the afterglow (Hagen et al., GCN 15139; Guidorzi et al., GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with AZT-22 telescope equipped with SNUCAM of Maidanak observatory in R filter. A preliminary photometry of combined images is based on SDSS stars (see at the bottom): T_start T0+ Filter, Exposure, OT (UT) (mid, d) (s) 2013-09-02T13:58:23 2.0410 R 1x600 22.20 +/- 0.10 2013-09-04T18:47:13 4.2555 R 5x600 22.53 +/- 0.07 2013-09-05T18:57:03 5.2658 R 6x600 22.90 +/- 0.07 A preliminary lc of the afterglow GRB 130831A based on our GCNs ##15185, 15186, 15188, 15189 and reported in this circular can be found in http://grb.rssi.ru/GRB130831A/grb130831A_lc_preliminary.PNG A power-law decay of the lc between 0.1 days and 2 days after trigger is -1.68 +/- 0.06 and marginally consistent with power-law decay reported by Watson (GCN 15179). Reference stars N SDSS id R(Lupton)errR 1 J235443.71+292539.3 13.491 0.016 2 J235438.60+292547.3 14.136 0.015 3 J235423.64+292452.8 17.120 0.016 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15237 SUBJECT: GRB 130831A: Maidanak optical observations, possible emerging Supernova DATE: 13/09/21 12:04:06 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), A. Volnova (IKI), B. Hafizov (UBAI), O. Burhonov (UBAI) report on behalf of larger GRB follow-up collaboration: We continue observation of the afterglow (Hagen et al., GCN 15139; Guidorzi et al., GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with AZT-22 telescope equipped with SNUCAM at Maidanak observatory. A preliminary photometry of combined images obtained on Sep. 16 is following: T_start T0+ Filter, Exposure, OT (UT) (mid, d) (s) 2013-09-16T19:00:13 16.28 R 14x300 22.77 +/- 0.07 The photometry is based on SDSS stars (see GCN 15190). This is brighter than we obtained on Sep. 9 (23.11 +/- 0.06) and on Sep. 15 (22.87 +/- 0.08). We suggest the observed re-brightening is an emerging Supernova associated with GRB 130831A. A preliminary lc of the afterglow+SN of GRB 130831A can be found in http://grb.rssi.ru/GRB130831A/grb130831A_lc_preliminary.PNG //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15242 SUBJECT: GRB 130831A: RATIR Confirmation of NIR/Optical Afterglow Flattening DATE: 13/09/22 15:05:22 GMT FROM: Nat Butler at Az State U William H. Lee (UNAM), Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), 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 again observed the field of GRB 130831A (Hagen, et al., GCN 15139) 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 2013/09 22.11 to 2013/09 22.31 UTC (21.57 to 21.77 days after the BAT trigger), obtaining a total of 6.40 hours exposure in the r and i bands and 2.60 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-XRT error circle (Evans et al., GCN 15147), in comparison with SDSS DR9 and 2MASS, we obtain the following detections and upper limits (3-sigma): r 23.02 +/- 0.14 i 22.78 +/- 0.13 Z > 22.87 Y > 22.35 J 21.62 +/- 0.19 H > 21.75 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. The flux levels are consistent with our prior upper limits measured 4 days after the GRB (Butler et al., GCN 15179) and with the measurements reported by Pozanenko et al. (GCN 15237), confirming a flattening of the afterglow light curve. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15244 SUBJECT: GRB 130831A: RTT150 optical observations DATE: 13/09/23 12:08:11 GMT FROM: Rodion Burenin at IKI, Moscow G. Khorunzhev, R. Burenin, M. Pavlinsky, R. Sunyaev (IKI), I. Bikmaev, N. Sakhibullin (KFU/AST), I. Khamitov, H. Kirbiyik (TUG) report: The optical afterglow of GRB 130831A (GCN 15139, D. Palmer) was observed with 1.5-m Russian-Turkish Telescope RTT150 at Bakyrlytepe (TUBITAK National Observatory, Turkey). The observation started at 2013-09-01 00:42:03 UT, appr. 12 hours after the burst. Two images each with exposure 300 seconds were obtained in R-band: 1. UT = 00:42:03.678; t-t0 = 11.630h; m_R = 19.57 +- 0.02 2. UT = 00:48:35.373; t-t0 = 11.739h; m_R = 19.62 +- 0.03 Images are calibrated using stars proposed by Pozanenko et al. (GCN 15190). The magnitudes are not corrected for the Galactic extinction. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15274 SUBJECT: GRB 130831A: Continued RATIR Optical and NIR Observations DATE: 13/09/30 16:17:13 GMT FROM: Nat Butler at Az State U William H. Lee (UNAM), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), Nat Butler (ASU), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), 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 GRB 130831A (Hagen, et al., GCN 15139) 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 2013/09 30.12 to 2013/09 30.49 UTC (29.58 to 29.94 days after the BAT trigger), obtaining a total of 6.27 hours exposure in the r and i bands and 2.65 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-XRT error circle (Evans et al., GCN 15147), in comparison with 2MASS, we obtain the following detections and upper limits (3-sigma): r 23.84 +/- 0.18 i 23.23 +/- 0.15 Z > 23.04 Y > 22.53 J > 22.37 H > 21.72 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. The source has faded relative to our last measurement (t~21.5 days; Lee et al., GCN 15242) by about 0.8 magnitudes in r and J and 0.5 magnitudes in i. Our measurements (see, also, Watson et al., GCN 15179; Butler et al., GCN 15165) are consistent with a bump or re-brightening in the lightcurve at t~10 days (see, Pozanenko et al., GCN 15237), followed by continued fading. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15320 SUBJECT: GRB 130831A: VLT/FORS2 spectroscopic detection of a supernova DATE: 13/10/09 09:54:39 GMT FROM: Sylvio Klose at TLS Tautenburg S. Klose, A. Nicuesa Guelbenzu (both TLS Tautenburg), T. Kruehler (ESO), J. Greiner, D. A. Kann, A. Rau, V. Sudilovsky (all MPE Garching), F. Olivares E. (UNAB, MCSS, Chile), and S. Schulze (PUC, MCSS, Chile), on behalf of a larger collaboration report: We observed the optical transient following GRB 130831A (e.g., Hagen et al. 2013, GCN 15139; Guidorzi et al. 2013, GCN 15140; Xu et al. 2013, GCN 15142; Yoshii et al. 2013, GCN 15143) with VLT/FORS2 equipped with the 300V grism on Sep 29 and Sep 30, 2013, between 28.5 and 29.5 days after the burst under excellent sky conditions with mean seeing around 0.6". The total exposure time of the spectrum was 1.53 hr and covers the spectral range between approximately 440 and 920 nm. In the combined spectrum, we detect the optical emission over the full spectral range. The spectrum peaks at about 800 nm and shows broad absorption features, very much reminiscent of the spectrum of, e.g., GRB 031203 / SN 2003lw (z=0.1055; Malesani et al. 2004, ApJ 609, L5), and the recent GRB 120714B / SN 2012eb (z=0.40; Klose et al. 2012, GCN 13613), GRB 130215A / SN 2013ez (z=0.597; de Ugarte Postigo et al., GCN 14303), GRB 130427A / SN 2013cq (z=0.34; Xu et al. 2013, ApJ 776, 98), and GRB 130702 / SN 2013dx (z=0.145; Schulze et al. 2013, GCN 14994), all obtained around SN maximum light. We conclude that we have spectroscopically discovered the appearence of a broad-line SN following GRB 130831A at z=0.4791 (Cucchiara et al. 2013, GCN 15144), confirming the conclusion of Pozanenko et al. (GCN 15237) based on the optical light curve. [GCN OPS NOTE(12oct13): Per author's request, VS was added to the author list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 15321 SUBJECT: GRB 130831A: Continued RATIR Optical and NIR Observations DATE: 13/10/09 21:22:00 GMT FROM: Alan M. Watson at Instituto de Astronomia UNAM William H. Lee (UNAM), Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), 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 GRB 130831A (Hagen, et al., GCN 15139) 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 2013/10 9.10 to 2013/10 9.47 UTC (925.41 to 934.19 hours after the BAT trigger), obtaining a total of 6.08 hours exposure in the r and i bands and 2.61 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-XRT error circle, in comparison with 2MASS, we obtain the following upper limits (3-sigma): r > 24.14 i > 23.63 Z > 22.94 Y > 22.45 J > 22.23 H > 21.74 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. As compared with our previous RATIR observations (Lee et al., GCN 15274) we confirm the fading in r and i by at least 0.3 and 0.4 and magnitudes, respectively. The upper limits in Z, Y, J, and H are also consistent with fading. Overall our measurements (Butler et al. GCN 15165, Watson et al. GCN 15179, Lee et al., GCN 15242, 15274) are consistent with the re-brightening due to a SN, as reported by Pozanenko et al. (GCN 15237) and spectroscopically by Klose et al. (GCN 15320), and fading. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18673 SUBJECT: GRB 130831A: MASTER early OT detection and LC DATE: 15/12/07 14:17:09 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E.Gorbovskoy, V. Lipunov, N.Tyurina, V.Kornilov, P.Balanutsa, A.Kuznetsov, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University After this observation night there was no electricity at the Tunka observatory for a few days . Therefore, the data were not immediately available. We forgot to check the follow-up after power is restored and rediscovered this source as optical transient during the data reprocessing of the present time. MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka was pointed to the GRB130831A 58 sec after trigger time at 2013-08-31 13:05:14 UT. On our second (20s exposure 120 sec after trigger) set we found 1 optical transient within SWIFT error-box (ra=23 54 36 dec=+29 27 00 r=0.05) brighter then 15.1. T-Tmid Date Time Expt. Ra Dec Mag -------|-----------|----------|-------|-----------------|-----------------|------- 130 2013-08-31 13:06:16 20 23h 54m 29.82s +29d 25m 47.1s 14.34 The 5-sigma upper limit has been about 15.1mag The automatic reduction data are below: date time coord2000 Exp. Polaroid mag err UT s 2013-08-31 13:05:13 - - 10 P/ >15.4 2013-08-31 13:05:14 - - 10 P\ >15.5 2013-08-31 13:06:14.969 23h 54m 29.77s +29d 25m 46s.5 20 P/ 14.19 0.13 2013-08-31 13:06:16.09 23h 54m 29.82s +29d 25m 47s.1 20 P\ 14.34 0.15 2013-08-31 13:07:37.707 23h 54m 29.94s +29d 25m 46s.6 40 P 13.70 0.07 2013-08-31 13:07:38.411 23h 54m 29.89s , +29d 25m 46s.3 40 P 14.08 0.08 2013-08-31 13:09:21.157 23h 54m 29.87s , +29d 25m 46s.5 60 P 13.96 0.06 2013-08-31 13:09:22.329 23h 54m 29.86s , +29d 25m 46s.3 60 P 14.17 0.06 2013-08-31 13:11:11.731 23h 54m 29.87s , +29d 25m 46s.8 80 P 13.96 0.05 2013-08-31 13:11:12.656 23h 54m 29.87s , +29d 25m 46s.4 80 P 14.05 0.04 2013-08-31 13:13:26.831 23h 54m 29.87s , +29d 25m 46s.4 110 P 13.14 0.02 2013-08-31 13:13:26.904 23h 54m 29.87s , +29d 25m 46s.7 110 P 13.23 0.01 2013-08-31 13:16:22.741 23h 54m 29.88s , +29d 25m 46s.4 140 P 12.76 0.01 2013-08-31 13:16:23.769 23h 54m 29.89s , +29d 25m 46s.7 140 P 12.79 0.01 2013-08-31 13:19:48.725 23h 54m 29.88s , +29d 25m 46s.5 180 P 13.10 0.01 2013-08-31 13:19:49.319 23h 54m 29.89s , +29d 25m 46s.6 180 P 13.03 0.01 2013-08-31 13:23:42.166 23h 54m 29.89s , +29d 25m 46s.6 180 P 13.44 0.01 2013-08-31 13:23:43.007 23h 54m 29.89s , +29d 25m 46s.6 180 P 13.40 0.01 2013-08-31 13:27:40.436 23h 54m 29.90s , +29d 25m 46s.5 180 P 13.80 0.01 2013-08-31 13:27:41.309 23h 54m 29.89s , +29d 25m 46s.7 180 P 13.79 0.01 2013-08-31 13:31:39.264 23h 54m 29.88s , +29d 25m 46s.7 180 P 14.08 0.02 2013-08-31 13:31:39.957 23h 54m 29.88s , +29d 25m 46s.8 180 P 14.12 0.01 2013-08-31 13:36:03.651 23h 54m 29.89s , +29d 25m 46s.4 180 P 14.44 0.02 2013-08-31 13:36:04.486 23h 54m 29.89s , +29d 25m 46s.5 180 P 14.51 0.02 2013-08-31 13:39:59.065 23h 54m 29.88s , +29d 25m 46s.6 180 P 14.55 0.02 2013-08-31 13:39:59.918 23h 54m 29.89s , +29d 25m 46s.7 180 P 14.53 0.02 2013-08-31 13:44:00.574 23h 54m 29.89s , +29d 25m 46s.7 180 P 14.72 0.02 2013-08-31 13:44:01.425 23h 54m 29.89s , +29d 25m 46s.6 180 P 14.78 0.03 2013-08-31 13:48:10.668 23h 54m 29.91s , +29d 25m 46s.5 180 P 14.94 0.03 2013-08-31 13:48:11.488 23h 54m 29.87s , +29d 25m 46s.5 180 P 14.95 0.02 2013-08-31 13:52:19.736 23h 54m 29.89s , +29d 25m 46s.3 180 P 14.97 0.03 2013-08-31 13:52:20.267 23h 54m 29.88s , +29d 25m 46s.3 180 P 14.99 0.03 2013-08-31 13:56:25.283 23h 54m 29.89s , +29d 25m 46s.7 180 P 15.11 0.03 2013-08-31 13:56:25.394 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.05 0.03 2013-08-31 14:00:30.776 23h 54m 29.88s , +29d 25m 46s.7 180 P 15.16 0.03 2013-08-31 14:00:31.465 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.13 0.03 2013-08-31 14:04:35.057 23h 54m 29.88s , +29d 25m 46s.5 180 P 15.18 0.03 2013-08-31 14:04:37.274 23h 54m 29.90s , +29d 25m 46s.8 180 P 15.10 0.03 2013-08-31 14:08:42.051 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.18 0.03 2013-08-31 14:08:42.358 23h 54m 29.89s , +29d 25m 46s.8 180 P 15.18 0.03 2013-08-31 14:13:16.808 23h 54m 29.88s , +29d 25m 46s.5 180 P 15.16 0.03 2013-08-31 14:13:17.534 23h 54m 29.87s , +29d 25m 46s.6 180 P 15.19 0.03 2013-08-31 14:17:26.33 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.22 0.03 2013-08-31 14:17:26.78 23h 54m 29.89s , +29d 25m 46s.7 180 P 15.16 0.03 2013-08-31 14:21:33.6 23h 54m 29.87s , +29d 25m 46s.4 180 P 15.33 0.03 2013-08-31 14:21:34.446 23h 54m 29.89s , +29d 25m 46s.6 180 P 15.27 0.03 2013-08-31 14:26:01.003 23h 54m 29.90s , +29d 25m 46s.7 180 P 15.37 0.03 2013-08-31 14:26:01.882 23h 54m 29.89s , +29d 25m 46s.5 180 P 15.30 0.03 2013-08-31 14:29:49.129 23h 54m 29.89s , +29d 25m 46s.7 180 P 15.45 0.03 2013-08-31 14:29:50.359 23h 54m 29.87s , +29d 25m 46s.7 180 P 15.39 0.03 2013-08-31 14:33:42.843 23h 54m 29.90s , +29d 25m 46s.4 180 P 15.47 0.03 2013-08-31 14:33:43.028 23h 54m 29.89s , +29d 25m 47s.0 180 P 15.46 0.04 2013-08-31 14:37:43.134 23h 54m 29.87s , +29d 25m 46s.4 180 P 15.52 0.04 2013-08-31 14:37:44.1 23h 54m 29.87s , +29d 25m 46s.6 180 P 15.42 0.04 2013-08-31 14:41:37.936 23h 54m 29.90s , +29d 25m 46s.5 180 P 15.66 0.04 2013-08-31 14:41:40.554 23h 54m 29.90s , +29d 25m 46s.5 180 P 15.57 0.04 2013-08-31 14:45:27.386 23h 54m 29.89s , +29d 25m 46s.4 180 P 15.71 0.04 2013-08-31 14:45:28.83 23h 54m 29.92s , +29d 25m 46s.7 180 P 15.54 0.04 2013-08-31 14:49:23.464 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.70 0.04 2013-08-31 14:49:24.934 23h 54m 29.89s , +29d 25m 46s.6 180 P 15.58 0.04 2013-08-31 14:53:18.194 23h 54m 29.88s , +29d 25m 46s.4 180 P 15.66 0.04 2013-08-31 14:53:18.686 23h 54m 29.90s , +29d 25m 46s.8 180 P 15.58 0.04 2013-08-31 14:57:36.995 23h 54m 29.87s , +29d 25m 46s.3 180 P 15.76 0.04 2013-08-31 14:57:37.418 23h 54m 29.90s , +29d 25m 46s.6 180 P 15.63 0.04 2013-08-31 15:01:42.896 23h 54m 29.91s , +29d 25m 46s.3 180 P 15.88 0.05 2013-08-31 15:01:43.521 23h 54m 29.92s , +29d 25m 46s.6 180 P 15.69 0.04 2013-08-31 15:05:42.207 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.95 0.04 2013-08-31 15:05:43.764 23h 54m 29.89s , +29d 25m 46s.7 180 P 15.75 0.04 2013-08-31 15:09:53.777 23h 54m 29.89s , +29d 25m 46s.4 180 P 15.93 0.05 2013-08-31 15:09:54.9 23h 54m 29.90s , +29d 25m 46s.5 180 P 15.84 0.05 2013-08-31 15:14:14.225 23h 54m 29.90s , +29d 25m 46s.5 180 P 16.04 0.05 2013-08-31 15:14:14.636 23h 54m 29.88s , +29d 25m 46s.5 180 P 15.90 0.05 2013-08-31 15:18:32.515 23h 54m 29.88s , +29d 25m 46s.4 180 P 15.98 0.05 2013-08-31 15:18:32.972 23h 54m 29.62s , +29d 25m 46s.7 180 P 16.80 0.08 2013-08-31 15:22:42.728 23h 54m 29.86s , +29d 25m 46s.4 180 P 16.13 0.05 2013-08-31 15:22:43.005 23h 54m 29.72s , +29d 25m 47s.5 180 P 16.50 0.08 2013-08-31 15:27:06.639 23h 54m 29.88s , +29d 25m 46s.1 180 P 16.23 0.06 2013-08-31 15:27:07.166 23h 54m 29.90s , +29d 25m 46s.6 180 P 15.99 0.06 2013-08-31 15:31:14.164 23h 54m 29.89s , +29d 25m 46s.5 180 P 16.32 0.06 2013-08-31 15:31:14.663 23h 54m 29.89s , +29d 25m 47s.1 180 P 16.06 0.06 2013-08-31 15:35:08.964 23h 54m 29.87s , +29d 25m 46s.4 180 P 16.39 0.07 2013-08-31 15:35:10.803 23h 54m 29.97s , +29d 25m 49s.0 180 P 16.83 0.10 2013-08-31 15:39:37.457 23h 54m 29.89s , +29d 25m 46s.7 180 P 16.47 0.07 2013-08-31 15:39:38.229 23h 54m 29.84s , +29d 25m 48s.1 180 P 16.73 0.10 2013-08-31 15:43:50.963 23h 54m 29.89s , +29d 25m 46s.6 180 P 16.51 0.07 2013-08-31 15:43:51.628 23h 54m 29.68s , +29d 25m 46s.2 180 P 17.30 0.14 2013-08-31 15:47:41.439 23h 54m 29.92s , +29d 25m 46s.8 180 P 16.41 0.08 2013-08-31 15:47:41.868 23h 54m 29.70s , +29d 25m 46s.3 180 P 16.70 0.10 2013-08-31 15:51:28.744 23h 54m 29.89s , +29d 25m 46s.7 180 P 16.57 0.08 2013-08-31 15:51:29.974 23h 54m 29.69s , +29d 25m 45s.8 180 P 16.99 0.12 2013-08-31 15:55:28.935 23h 54m 29.91s , +29d 25m 46s.6 180 P 16.68 0.11 2013-08-31 15:55:29.91 23h 54m 29.92s , +29d 25m 46s.6 180 P 16.36 0.10 2013-08-31 15:59:32.081 23h 54m 29.88s , +29d 25m 46s.5 180 P 16.78 0.09 2013-08-31 15:59:32.882 23h 54m 29.77s , +29d 25m 45s.2 180 P 16.75 0.10 2013-08-31 16:03:45.019 23h 54m 29.89s , +29d 25m 46s.2 180 P 16.71 0.09 2013-08-31 16:03:45.878 23h 54m 29.73s , +29d 25m 49s.2 180 P 16.98 0.13 2013-08-31 16:03:45.878 23h 54m 29.67s , +29d 25m 45s.0 180 P 17.21 0.14 2013-08-31 16:07:40.752 23h 54m 29.87s , +29d 25m 46s.7 180 P 16.68 0.10 2013-08-31 16:07:40.756 23h 54m 29.85s , +29d 25m 46s.9 180 P 16.53 0.11 2013-08-31 16:11:45.003 23h 54m 29.89s , +29d 25m 46s.5 180 P 16.65 0.09 2013-08-31 16:11:46.074 23h 54m 29.68s , +29d 25m 47s.0 180 P 16.51 0.11 2013-08-31 16:16:04.472 23h 54m 29.89s , +29d 25m 46s.2 180 P 16.90 0.11 2013-08-31 16:16:05.21 23h 54m 29.71s , +29d 25m 46s.2 180 P 17.15 0.14 2013-08-31 16:20:16.552 23h 54m 29.88s , +29d 25m 46s.4 180 P 16.71 0.09 2013-08-31 16:20:16.892 23h 54m 29.90s , +29d 25m 47s.3 180 P 16.63 0.12 2013-08-31 16:24:28.011 23h 54m 29.92s , +29d 25m 46s.2 180 P 16.74 0.12 2013-08-31 16:24:28.419 23h 54m 29.64s , +29d 25m 46s.9 180 P 17.97 0.22 2013-08-31 16:28:38.273 23h 54m 29.91s , +29d 25m 46s.3 180 P 16.75 0.11 2013-08-31 16:28:39.181 23h 54m 29.66s , +29d 25m 47s.7 180 P 17.10 0.16 2013-08-31 16:32:35.03 23h 54m 29.88s , +29d 25m 46s.4 180 P 17.03 0.12 2013-08-31 16:36:41.311 23h 54m 29.91s , +29d 25m 46s.9 180 P 16.88 0.13 2013-08-31 16:36:41.982 23h 54m 29.90s , +29d 25m 45s.2 180 P 16.91 0.14 2013-08-31 16:40:40.333 23h 54m 29.85s , +29d 25m 46s.5 180 P 17.07 0.15 2013-08-31 16:40:40.788 23h 54m 29.80s , +29d 25m 46s.5 180 P 18.57 0.32 The automatic light curve is available at http://observ.pereplet.ru/images/GRB130831A.jpg The message may be cited.