//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20540 SUBJECT: GRB 170127B: Swift detection of a short burst DATE: 17/01/27 15:25:04 GMT FROM: Jamie A. Kennea at PSU/Swift-XRT J. K. Cannizzo (NASA/UMBC), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), A. Cholden-Brown (PSU), A. D'Ai (INAF-IASFPA), V. D'Elia (ASDC), P.A. Evans (U Leicester), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 15:13:28 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170127B (trigger=735331). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 19.944, -30.338, which is RA(J2000) = 01h 19m 47s Dec(J2000) = -30d 20' 14" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single spike structure with a duration of about 0.2 sec. The peak count rate was ~8000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 15:14:43.3 UT, 74.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 19.9766, -30.3588 which is equivalent to: RA(J2000) = 01h 19m 54.37s Dec(J2000) = -30d 21' 31.6" with an uncertainty of 2.9 arcseconds (radius, 90% containment). This location is 125 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 2.01 x 10^20 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 113 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. Burst Advocate for this burst is J. K. Cannizzo (cannizzo AT milkyway.gsfc.nasa.gov). 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: 20541 SUBJECT: GRB 170127B: MASTER-Kislovodsk early optical observations DATE: 17/01/27 16:05:37 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.V.Chazov Lomonosov Moscow State University, Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Senik Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, A. Gabovich, Yu.Sergienko Blagoveschensk Educational State University, Blagoveschensk K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, O. Ershova Irkutsk State University R. Podesta, Claudio Mallamaci, Carlos Lopez and Federico Podesta Observatorio Astronomico Felix Aguilar (OAFA) Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Kislovodsk was pointed to the GRB170127B 37 sec after notice time and 52 sec after trigger time at 2017-01-27 15:14:21 UT in two polarization. On our first (10s exposure) set we haven`t found optical transient within SWIFT error-box (Cannizzo et al GCN 20540). The 5-sigma upper limit has been about 17.0 mag on single (10 s) and 19.5 on coadd (total exposure 540 s) images. The message may be cited. ==================================================================== The observations made on zenit distance = 76 degrees, galaxy latitude b = -83 degree. The moon ( 0 % bright part) below the horizon (The altitude of the Moon is -14 degree ). Observations started at twilight. The sun altitude is -11.4 degree. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20549 SUBJECT: GRB 170127B: NOT r-band upper limits DATE: 17/01/27 21:08:30 GMT FROM: Zach Cano at U of Iceland ​Z. Cano (IAA-CSIC), K. E. Heintz (Univ. Iceland & DARK/NBI), D. Malesani (​DARK/NBI and DTU Space​)​ & R. Tronsgaard (NOT) report on behalf of a larger collaboration: We observed the field of short-duration GRB 170127B (Cannizzo et al.; GCN Circ. 20540) with the 2.5-m Nordic Optical Telescope equipped with ALFOSC, starting at 19:48:56 UT on 27 January 2017 (4.59 hrs from detection). We obtained 3x300 s in the r-band. In our co-added image no new object is detected in the XRT error circle to the following limit: Filter t-t0 (hr) magnitude (AB) ------------------------------------------- r 4.73 >23.4 The r-band upper limit is for an isolated point source in the GRB field, which is calibrated to local Pan-STARRS standards in the field. This upper limit is not corrected for foreground extinction (E(B-V) = 0.02 mag, Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20550 SUBJECT: GRB 170127B: Enhanced Swift-XRT position DATE: 17/01/27 22:16:33 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 1434 s of XRT Photon Counting mode data and 2 UVOT images for GRB 170127B, 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 = 19.97709, -30.35807 which is equivalent to: RA (J2000): 01h 19m 54.50s Dec (J2000): -30d 21' 29.1" with an uncertainty of 2.0 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: 20551 SUBJECT: GRB 170127B: Fermi GBM observation DATE: 17/01/27 22:28:58 GMT FROM: Peter Veres at UAH P. Veres and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 15:13:28.77 UT on 27 January 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170127B (trigger 507222813 / 170127634) which was also detected by the Swift/BAT (Cannizzo et al., GCN 20540). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 44 degrees. The GBM light curve shows two overlapping pulses with a duration (T90) of about 1.7 s (50-300 keV). The time-averaged spectrum from T0-0.1 s to T0+0.4 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.67 +/- 0.16 and the cutoff energy, parameterized as Epeak, is 688 +/- 195 keV. The event fluence (10-1000 keV) in this time interval is (7.6 +/- 0.6)E-7 erg/cm^2. The 64 ms peak photon flux measured starting from T0-64 ms in the 10-1000 keV band is 8.4 +/- 1.2 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: 20554 SUBJECT: GRB 170127B: Swift/UVOT Upper Limits DATE: 17/01/28 02:36:04 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and J. K. Cannizzo (NASA/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 170127B 114 s after the BAT trigger (Cannizzo et al., GCN Circ. 20540). No optical afterglow consistent with the enhanced XRT position (Goad et al. GCN Circ. 20550) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposures and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 114 264 147 >21.2 u_FC 327 576 246 >19.9 white 114 1377 373 >21.0 v 656 1427 97 >19.4 u 327 576 246 >19.9 The magnitudes in the table 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: 20560 SUBJECT: GRB 170127B: Swift-XRT refined Analysis DATE: 17/01/28 15:25:05 GMT FROM: Phil Evans at U of Leicester K.L. Page (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), B. Mingo (U. Leicester), A.P. Beardmore (U. Leicester) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team: We have analysed 2.8 ks of XRT data for GRB 170127B, from 60 s to 10.6 ks after the BAT trigger. The data comprise 7 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=1.7 (+0.5, -0.4). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.57 (+0.27, -0.23). The best-fitting absorption column is consistent with the Galactic value of 2.0 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.1 x 10^-11 (4.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.0 (+/-4.2) x 10^20 cm^-2 Galactic foreground: 2.0 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.57 (+0.27, -0.23) If the light curve continues to decay with a power-law decay index of 1.7, the count rate at T+24 hours will be 6.7 x 10^-6 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.7 x 10^-16 (2.8 x 10^-16) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00735331. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20566 SUBJECT: GRB 170127B: Swift-BAT refined analysis DATE: 17/01/29 16:03:01 GMT FROM: Amy Lien at GSFC T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), J. K. Cannizzo (NASA/UMBC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), J. P. Norris (BSU), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170127B (trigger #735331) (Cannizzo et al., GCN Circ. 20540). The BAT ground-calculated position is RA, Dec = 19.997, -30.340 deg which is RA(J2000) = 01h 19m 59.2s Dec(J2000) = -30d 20' 25.2" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 75%. The mask-weighted light curve shows a single-peaked structure that starts and peaks at ~T0, and ends at ~T+0.6 s. T90 (15-350 keV) is 0.51 +- 0.14 sec (estimated error including systematics). The time-averaged spectrum from T+0.05 to T+0.64 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.89 +- 0.25. The fluence in the 15-150 keV band is 1.0 +- 0.2 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.16 sec in the 15-150 keV band is 1.1 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. Using a 8-ms binned light curve, the lag analysis finds a lag of -4 (-17, +8) ms for the 100-350 keV to 25-50 keV, and -12 (-8, +8) ms for the 50-100 keV to 15-25 keV band. These values are consistent with those of a short GRB. Moreover, no extended emission are found. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/735331/BA/