//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13993 SUBJECT: GRB 121125A: Swift detection of a burst with optical counterpart DATE: 12/11/25 08:43:43 GMT FROM: Scott Barthelmy at NASA/GSFC B. N. Barlow (PSU), S. D. Barthelmy (GSFC), D. Grupe (PSU), E. A. Helder (PSU) and C. J. Mountford (U Leicester) report on behalf of the Swift Team: At 08:32:27 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 121125A (trigger=539563). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 228.520, +55.322 which is RA(J2000) = 15h 14m 05s Dec(J2000) = +55d 19' 18" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multiple-peaked structure with a duration of about 70 sec. The peak count rate was ~4600 counts/sec (15-350 keV), at ~34 sec after the trigger. The XRT began observing the field at 08:33:34.1 UT, 66.8 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 228.52496, 55.31330 which is equivalent to: RA(J2000) = 15h 14m 05.99s Dec(J2000) = +55d 18' 47.9" with an uncertainty of 4.1 arcseconds (radius, 90% containment). This location is 32 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 in excess of the Galactic value (1.27 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.7 (+2.20/-1.89) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 4.27e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 75 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 15:14:06.54 = 228.52724 DEC(J2000) = +55:18:48.0 = 55.31332 with a 90%-confidence error radius of about 0.74 arc sec. This position is 1.2 arc sec. from the center of the XRT error circle. The estimated magnitude is 16.19 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.01. Burst Advocate for this burst is B. N. Barlow (bnb2 AT 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: 13994 SUBJECT: GRB 121125A: MASTER-NET optical observations DATE: 12/11/25 09:52:04 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, A.Belinski, N.Tyurina, N.Shatskiy, P.Balanutsa, D.Zimnukhov, A.Kuznetsov, V.V.Chazov, D.Denisenko, A.Sankovich Sternberg Astronomical Institute, Moscow State University K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk Irkutsk State University V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Blagoveschensk was pointed to the GRB121125.36 44 sec after GRB time at 2012-11-25 08:33:11.383 UT. On our first (10s exposure) set we haven`t found optica l transient within SWIFT error-box (Barlow et al., GCN Circ 13993). Unfortunately notice alert have come immodiatly after sunset when telescope prepearing calibration images. So 5-sigma upper limit of the first images has been about 13.8 mag that is not very good. We see OT (Barlow et al., GCN Circ 13993) on UVOT position on the next images with 14.5 mag limit (UT_start = 2012-11-25 08:34:34, 127 s after trigger time, exp_time = 30s). We note that there is 16.5 mag star 9 arcsec from UVOT OT coordinates. The observations is continuated. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13995 SUBJECT: GRB 121125A: LOAO Observation DATE: 12/11/25 16:47:57 GMT FROM: Myungshin Im at Seoul Nat U M. Im (CEOU/SNU) and Y. Urata (NCU) on behalf of EAFON. We observed the field of GRB 121125A (Barlow et al., GCN 13993) in B and R filters using the 1-m telescope at Mt. Lemmon observatory in Arizona, US. The observation started at 2012-11-25 12:24:27 UT, or about 3.87 hours after the BAT alert, and continued for about 30 min. We identify an object in stacked images of both B and R at RA=15:14:06.586, Dec=55:18:47.95 with rms error of 0.6". This is consistent with the UVOT coordinate of the afterglow candidate reported in Barlow et al. The object has R-band magnitude of R = 19.29 +- 0.14 mag, calibrated against R2 magnitude (16.13 mag) of a USNO-B1 star at RA=15:14:07.14, Dec=+55:18:40.30. Combined with the result from Yurkov et al. (GCN 13994) and Barlow et al., our result reveals a fading behavior of the object, thus we identify the object to be the afterglow of GRB 121125A. We thank the LOAO operator, Jae-Hyuk Yoon for performing the observation. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13996 SUBJECT: GRB 121125A: Swift-BAT refined analysis DATE: 12/11/25 20:28:47 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), B. N. Barlow (PSU), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), 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-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 121125A (trigger #539563) (Barlow, et al., GCN Circ. 12993). The BAT ground-calculated position is RA, Dec = 228.519, 55.318 deg, which is RA(J2000) = 15h 14m 04.6s Dec(J2000) = +55d 19' 03.5" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 80%. The mask-weighted light curve shows two clusters of overlapping peaks that start at ~T-7 sec, peaks at ~T+37 sec, and ends at ~T+100 sec. T90 (15-350 keV) is 52.2 +- 4.6 sec (estimated error including systematics). The time-averaged spectrum from T-6.31 to T+77.64 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.52 +- 0.06. The fluence in the 15-150 keV band is 4.7 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+36.56 sec in the 15-150 keV band is 2.9 +- 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/539563/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13997 SUBJECT: GRB 121125A: Fermi GBM Observation DATE: 12/11/25 21:08:30 GMT FROM: Sinead McGlynn at Excellence Cluster/TUM Sinead McGlynn (MPE/TUM) reports on behalf of the Fermi GBM Team: "At 08:32:29.63 UT on 25 Nov 2012, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 121125A (trigger 375525152/121125356), which was also detected by the Swift/BAT (Barthelmy et al. 2012, GCN 13996). The GBM on-ground location is consistent with the Swift/UVOT afterglow candidate position (Barlow et al. 2012, GCN 13993). The on-ground calculated location, using the GBM trigger data, is RA = 229.30, DEC = +54.14 (J2000 degrees, equivalent to 15h 17m 12s, 54d 08' 24"), with an uncertainty of 2.22 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 37 degrees. The GBM light curve shows/consists of several pulses with a duration (T90) of about 50 s (50-300 keV). The time-averaged spectrum from T0-11.3 s to T0+49.1 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.38 +/- 0.06 and the cutoff energy, parameterized as Epeak, is 196 +/- 26 keV. The event fluence (10-1000 keV) in this time interval is (9.5 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+32 s in the 10-1000 keV band is 4.2 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 13998 SUBJECT: GRB 121125A: Enhanced Swift-XRT position DATE: 12/11/25 22:06:30 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 4397 s of XRT Photon Counting mode data and 10 UVOT images for GRB 121125A, 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 = 228.52806, +55.31335 which is equivalent to: RA (J2000): 15h 14m 6.73s Dec (J2000): +55d 18' 48.1" with an uncertainty of 1.5 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: 13999 SUBJECT: GRB 121125A: Swift-XRT refined Analysis DATE: 12/11/25 23:43:03 GMT FROM: Phil Evans at U of Leicester B. Sbarufatti (INAF-OAB/PSU), G. Stratta (ASDC), M.C. Stroh (PSU), D.N. Burrows (PSU), J.A. Kennea (PSU), P.A. Evans (U. Leicester), O.M. Littlejohns (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB) and B.N. Barlow report on behalf of the Swift-XRT team: We have analysed 9.6 ks of XRT data for GRB 121125A (Barlow et al. GCN Circ. 13993), from 73 s to 23.5 ks after the BAT trigger. The data comprise 196 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN. Circ 13998). The late-time light curve (from T0+4.0 ks) can be modelled with a power-law decay with a decay index of alpha=1.28 (+/-0.08). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.02 (+0.10, -0.09). The best-fitting absorption column is 1.49 (+0.23, -0.22) x 10^21 cm^-2, in excess of the Galactic value of 1.3 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index of 2.14 (+0.13, -0.12) and a best-fitting absorption column of 1.02 (+0.28, -0.26) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.02 (+0.28, -0.26) x 10^21 cm^-2 Galactic foreground: 1.3 x 10^20 cm^-2 Excess significance: 5.6 sigma Photon index: 2.14 (+0.13, -0.12) If the light curve continues to decay with a power-law decay index of 1.28, the count rate at T+24 hours will be 0.013 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.2 x 10^-13 (5.7 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00539563. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14002 SUBJECT: GRB 121125A: Swift/UVOT Detection DATE: 12/11/26 22:17:56 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and B. N. Barlow (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 121125A 75 s after the BAT trigger (Barlow et al., GCN Circ. 13993). A source consistent with the XRT position (Goad et al., GCN Circ. 13998) is detected in the initial UVOT exposures. The refined UVOT position is: RA (J2000) = 15:14:06.58 = 228.52740 (deg.) Dec (J2000) = +55:18:48.0 = 55.31332 (deg.) with an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 75 225 147 16.35 +/- 0.03 v 4693 4892 197 19.11 +/- 0.19 b 4076 4276 197 19.31 +/- 0.13 u 288 423 134 16.21 +/- 0.04 w1 5103 5302 197 20.06 +/- 0.32 m2 4897 11750 1082 >21.9 w2 4488 6123 393 >21.6 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 14020 SUBJECT: GRB 121125A: optical upper limit DATE: 12/11/29 17:52:31 GMT FROM: Alina Volnova at SAI MSU A. Volnova (SAI MSU, IKI), D. Varda (ISON), E. Sinyakov (ISON), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 121125A (Barlow et al., GCN 13993) with ORI-25 telescope of ISON-Blagoveshensk observatory starting on Nov.25 (UT) 09:05:39. We took several unfiltered images. We do not detect the OT (Barlow et al., GCN 13993; Yurkov et al., GCN 13994; Im et al., GCN 13995) in any combined images. A photometry of stacked image is based on nearby USNO-B1.0 stars (R2): T_start T0+, Filter, exposure, UL (3 sigma) (UT) mid (d) (s) 08:58:19 0.03078 none 52 x 40 15.6