//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20538 SUBJECT: GRB 170127A: Swift detection of a burst DATE: 17/01/27 14:33:09 GMT FROM: Scott Barthelmy at NASA/GSFC C. B. Markwardt (NASA/GSFC), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), A. Cholden-Brown (PSU), A. D'Ai (INAF-IASFPA), V. D'Elia (ASDC), 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 14:21:15 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170127A (trigger=735326). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 174.336, -45.852, which is RA(J2000) = 11h 37m 21s Dec(J2000) = -45d 51' 05" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a couple weak peaks with a duration of about 35 sec. The peak count rate was ~900 counts/sec (15-350 keV), at ~5 sec after the trigger. The XRT began observing the field at 14:22:51.5 UT, 95.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 174.35974, -45.83603 which is equivalent to: RA(J2000) = 11h 37m 26.34s Dec(J2000) = -45d 50' 09.7" with an uncertainty of 4.1 arcseconds (radius, 90% containment). This location is 82 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. No spectrum from the promptly downlinked event data is yet available to determine the column density. The initial flux in the 2.5 s image was 7.10e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 250 seconds with the U filter starting 101 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 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.07. Burst Advocate for this burst is C. B. Markwardt (Craig.Markwardt AT 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: 20539 SUBJECT: GRB 170127A: Prompt enhanced Swift-XRT position DATE: 17/01/27 14:57:53 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Using promptly downlinked XRT event data for GRB 170127A, we find an enhanced XRT position of the afterglow: RA, Dec: 174.3600, -45.8358 which is equivalent to: RA (J2000) = 11 37 26.41 Dec (J2000) = -45 50 08.7 with an uncertainty of 2.2 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/735326. Position enhancement is is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// 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: 20543 SUBJECT: GRB 170127C: Fermi GBM detection DATE: 17/01/27 16:56:33 GMT FROM: Elisabetta Bissaldi at U.Innsbruk/IAPP E. Bissaldi (Politecnico & INFN Bari), B. Mailyan and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 01:35:47.79 UT on 27 January 2017, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 170127C (trigger 507173752 / 170127067). The on-ground calculated location, using the GBM trigger data, is RA, Dec = 336.380, -63.400 (J2000 degrees, equivalent to 22 h 25 m, -63 d 24 '), with an uncertainty of 1.95 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32]). The trigger resulted in an Autonomous Repoint Request (ARR) by the GBM Flight Software owing to the high peak flux of the GRB. This ARR was accepted and the spacecraft slewed to the GBM in-flight location. The initial angle from the Fermi-LAT boresight to the GBM ground location is 140 degrees. The GBM light curve consists of single peak with a duration (T90) of about 0.210 s (50-300 keV). The time-averaged spectrum from T0-0.064 s to T0+0.192 s is well fit by a power law function with an exponential high-energy cutoff. The power law index is 0.27 +/- 0.09 and the cutoff energy, parameterized as Epeak, is 859 +/- 34 keV. The event fluence (10-1000 keV) in this time interval is (7.4 +/- 0.2)E-06 erg/cm^2. The 64-ms peak photon flux measured starting from T0 in the 10-1000 keV band is 84 +/- 5 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: 20544 SUBJECT: GRB 170127C: Fermi-LAT detection DATE: 17/01/27 17:11:28 GMT FROM: Magnus Axelsson at Stockholm U. E. Moretti (MPP), G. Vianello (Stanford Univ.), E. Bissaldi (INFN and Politecnico Bari), J. Racusin (NASA/GSFC) and M. Axelsson (Stockholm Univ. and KTH Stockholm) report on behalf of the Fermi-LAT team: On January, 27, 2017 Fermi-LAT detected high-energy emission from GRB 170127C, which was also detected by Fermi-GBM starting at T0 = 01:35:47.79 (trigger 507173752 / 170127067; Bissaldi et al. GCN 20543). The best LAT on-ground location is found to be RA, Dec = 339.3, -63.9 (J2000) with an error radius of 0.4 deg (90 % containment, statistical error only). The location was outside the LAT field-of-view at the time of the trigger. The event triggered an autonomous repoint of the spacecraft, causing the location to enter the field-of-view around 300s later. The data from the Fermi-LAT show a significant increase in the event rate that is spatially correlated with the trigger with high significance. The highest-energy photon is a 500 MeV event which is observed 2890 seconds after the GBM trigger. A total of 5 photons above 100 MeV were detected up to 4000s after the trigger. A Swift ToO has been requested for this burst. The Fermi-LAT point of contact for this burst is Elena Moretti (moretti@mpp.mpg.de). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20545 SUBJECT: GRB 170127C (Fermi/GBM trigger 507173752): AGILE analysis DATE: 17/01/27 17:15:24 GMT FROM: Francesco Verrecchia at ASDC AGILE analysis of GRB 170127C (Fermi/GBM trigger 507173752) A. Ursi (INAF/IAPS), P. Munar-Adrover (INAF/IAPS), F. Verrecchia (ASDC and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), Y. Evangelista (INAF/IAPS), F. Lucarelli (ASDC and INAF/OAR), F. Fuschino (INAF/IASF-Bo), I. Donnarumma (INAF/IAPS), G. Minervini (INAF/IAPS), M. Marisaldi (INAF/IASF-Bo and Bergen University), A. Bulgarelli, V. Fioretti (INAF/IASF-Bo), C. Pittori (ASDC and INAF/OAR), G. Piano, A. Argan, E. Del Monte, L. Pacciani (INAF/IAPS), M. Cardillo (INAF/OA-Arcetri and INAF/IAPS), A. Giuliani (INAF/IASF-Mi), M. Pilia, A. Trois (INAF/OA-Cagliari), F. Longo (Univ. Trieste and INFN Trieste), report on behalf of the AGILE Team: We performed an analysis of AGILE data of the GRB 170127C (Fermi/GBM trigger num 507173752; GCN #20543), which occurred at 2017-01-27 01:35:47.79 UTC. The Mini-CALorimeter (MCAL), sensitive in the energy range from 400 keV to 100 MeV, detected a short burst at T0 = 2017-01-27 01:35:47.9294 UTC, that triggered both the on-board 16 ms and 64 ms timescale hardware logic system. The MCAL light curve shows a sharp single peak, that lasted about 0.13 s and released a total number of ~980 counts above 400 keV in the detector, above an average background rate of 590 counts/s. The time-integrated spectrum measured between T0 and T0+0.13 s can be fit in the energy range 0.5 - 20 MeV with a power law with high-energy cut-off at 1.63 MeV, with photon index -1.64±0.19 and reduced chi-squared 1.08 (18 d.o.f.). As observed by MCAL, the burst fluence in the same energy range and time interval is 1.20±0.01e-6 erg cm-2. All quoted errors are at 90% confidence levels. SuperAGILE, sensitive in the energy range 18 to 60 keV, also clearly detected the burst with its ratemeters. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20546 SUBJECT: GRB 170127C: Tiled Swift observations DATE: 17/01/27 18:35:17 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the Fermi/LAT GRB 170127C. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00063 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the Fermi/LAT event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20548 SUBJECT: GRB 170127A: Enhanced Swift-XRT position DATE: 17/01/27 19:24:11 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 1366 s of XRT Photon Counting mode data and 2 UVOT images for GRB 170127A, 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 = 174.35970, -45.83565 which is equivalent to: RA (J2000): 11h 37m 26.33s Dec (J2000): -45d 50' 08.3" with an uncertainty of 2.4 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: 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: 20552 SUBJECT: GRB 170127A: Swift/UVOT Upper Limits DATE: 17/01/27 22:44:14 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and C. B. Markwardt (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 170127A 102 s after the BAT trigger (Markwardt et al., GCN Circ. 20538). No optical afterglow consistent with the enhanced XRT position (Evans et al. GCN Circ. 20548) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u_FC 102 351 246 >20.5 v 409 1533 136 >18.7 b 359 1632 175 >20.4 u 102 1607 529 >20.7 w1 458 1583 136 >19.4 m2 434 1558 136 >20.0 w2 385 1658 175 >20.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.07 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// 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: 20558 SUBJECT: GRB 170127A: Swift-XRT refined Analysis DATE: 17/01/28 11:12:10 GMT FROM: Phil Evans at U of Leicester J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), B. Mingo (U. Leicester) and report on behalf of the Swift-XRT team: report on behalf of the Swift-XRT team: We have analysed 6.2 ks of XRT data for GRB 170127A, from 86 s to 58.8 ks after the BAT trigger. The data comprise 168 s in Windowed Timing (WT) mode (the first 7 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The light curve can be modelled with an initial power-law decay with an index of alpha=1.28 (+/-0.15), followed by a break at T+329 s to an alpha of 8.0 (+0.0, -1.1). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.49 (+/-0.10). The best-fitting absorption column is 1.3 (+/-0.4) x 10^21 cm^-2, in excess of the Galactic value of 8.5 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 4.5 x 10^-11 (5.0 x 10^-11) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 1.3 (+/-0.4) x 10^21 cm^-2 Galactic foreground: 8.5 x 10^20 cm^-2 Excess significance: 2.0 sigma Photon index: 1.49 (+/-0.10) If the light curve continues to decay with a power-law decay index of 5.19, the count rate at T+24 hours will be 2.0 x 10^-13 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.9 x 10^-24 (10.0 x 10^-24) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00735326. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// 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: 20561 SUBJECT: GRB 170127C: AstroSat CZTI detection DATE: 17/01/28 17:45:19 GMT FROM: Vidushi Sharma at IUCAA V. Sharma, D. Bhattacharya and V. Bhalerao (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data showed clear detection of GRB170127C (Fermi detection: E. Bissaldi et al., GCN Circ. 20543) in the 40-200 keV energy range. The light curve shows single peak structure with main peak at 01:35:47.79 UT, coincident with Fermi trigger. The measured peak count rate is 895.2 counts/sec above the background in combined data of four quadrants, with a total 904.3 counts. The local mean background count rate was 416.8 counts/sec. Using cumulative rates, we measure a T90 of 0.91 secs. It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20562 SUBJECT: GRB 170127A: GROND Upper limits DATE: 17/01/28 17:52:34 GMT FROM: Patricia Schady at MPE/Swift P. Schady, P. Wiseman and J. Greiner (all at MPE Garching) report on behalf of the GROND team: We observed the field of GRB 170127A (Swift trigger 735326; Markwardt et al., GCN #20538) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile). Observations started at 05:23 UT on 2017-01-27, 15 hrs after the GRB trigger. They were performed at high seeing that varied between 1.5” and 2" and at an average airmass of 1.4. In combined images with 36 min of total exposures in g’r'i'z' and 30 min in JHK at a mid-time of 05:40 UT on 2017-01-28, we do not detect a source within the Swift-XRT error circle reported by Evans et al. (GCN #20548) down to the following 3 sigma upper limits (all in AB system) g' > 24.0 mag r' > 23.7 mag i' > 23.1 mag z' > 23.0 mag J > 20.7 mag H > 20.3 mag K > 17.7 mag Given magnitudes are calibrated against GROND zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.06 in the direction of the burst (Schlafly & Finkbeiner 2011). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20563 SUBJECT: GRB 170127C: POLAR Observation DATE: 17/01/29 07:32:35 GMT FROM: Radek Marcinkowski at PSI/POLAR R. Marcinkowski (PSI), H.L. Xiao (PSI), W. Hajdas (PSI), Yi Zhao (IHEP), M. Kole (DPNC) and S.L. Xiong (IHEP) report on behalf of the POLAR collaboration: At 2017-01-27 01:35:48.7 UT(T0), during a routine on-ground search of data, POLAR detected GRB 170127C, which was also observed by Fermi GBM (trigger # 507173752) and reported by Fermi GBM (Bissaldi et al. GCN 20543), Fermi-LAT (E. Moretti et al. GCN 20544), Agile (A. Ursi et al. GCN 20545) and AstroSat (V. Sharma et al. GCN 20561). The POLAR light curve consists of 1 short (~0.15 s), strong peak followed by longer and weaker multi peak structure with duration (T90) of 22.0 +/- 0.2 s measured from T0. The light curve is compatible with the one from Fermi-GBM. The 0.2 s peak flux at T0 + 0.2 s is equal to 13000 +/- 140 counts/sec. POLAR recorded 3600 +/- 140 events from the burst. Above measurements are in the energy range of about 20 - 500 keV. LC_URL: http://polar.psi.ch/triggers/GRB_170127C_raw.png or http://polar.psi.ch/pub/lc.php?event=GRB+170127C Using the best location from Fermi LAT (E. Moretti et al. GCN 20544), which is: RA : 339.3 [deg] Dec: -63.9 [deg] Err: 0.4 [deg] the incident angle in the POLAR coordinate at T0 is: Theta: 41.8 [deg] Phi: 157.6 [deg] The analysis results presented above are preliminary. Calibration of the instrument is ongoing. POLAR is a dedicated Gamma-Ray Burst polarimeter which was launched on-board the Chinese space laboratory Tiangong-2 (TG-2) on Sep 15, 2016. The energy detection range of POLAR is ~ 50-500 keV. More information about POLAR can be found at http://polar.psi.ch/pub , http://polar.ihep.ac.cn/en/ and http://isdc.unige.ch/polar/ . This message is quotable in publications. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20564 SUBJECT: GRB 170127C: Swift-XRT observations DATE: 17/01/29 12:05:26 GMT FROM: Valerio D'Elia at ASDC V. D’Elia (ASDC) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 170127C (Bissaldi et al., GCN Circ 20543, Moretti et al., GCN Circ 20544) in a series of observations tiled on the sky. The total exposure time is 5 ks, distributed over 7 tiles; the maximum exposure at a single sky location was 1.4 ks. The data were collected between T0+61.2 and T0+77.4 ks and are entirely in Photon Counting (PC) mode. No new source is detected in the XRT field of view, at a count rate limit in the range 0.005-0.01 cts/s. The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, areavailable at http://www.swift.ac.uk/xrt_products/TILED_GRB00063. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20565 SUBJECT: GRB 170127A: Swift-BAT refined analysis DATE: 17/01/29 16:00:54 GMT FROM: Amy Lien at GSFC M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170127A (trigger #735326) (Markwardt et al., GCN Circ. 20538). The BAT ground-calculated position is RA, Dec = 174.382, -45.827 deg which is RA(J2000) = 11h 37m 31.6s Dec(J2000) = -45d 49' 38.6" with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 97%. The mask-weighted light curve shows some weak overlapping pulses that starts at ~T-5 s and ends at ~T+65 s. T90 (15-350 keV) is 62.26 +- 10.39 sec (estimated error including systematics). The time-averaged spectrum from T-4.65 to T+64.51 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.10 +- 0.30. The fluence in the 15-150 keV band is 5.2 +- 1.0 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+7.31 sec in the 15-150 keV band is 0.3 +- 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/735326/BA/ //////////////////////////////////////////////////////////////////////// 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/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 20567 SUBJECT: Konus-Wind observation of GRB 170127C (short/hard GRB with extended emission) DATE: 17/01/29 16:15:14 GMT FROM: Dmitry Frederiks at Ioffe Institute D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report: The short/hard GRB 170127C (Fermi-GBM detection: Bissaldi et al., GCN 20543; Fermi-LAT detection: Moretti et al., GCN 20544; AGILE analysis: Ursi et al., GCN 20545; AstroSat CZTI Sharma: Verrecchia et al., GCN 20561; POLAR observation: Marcinkowski et al., GCN 20563) triggered Konus-Wind at T0=5744.660 s UT (01:35:44.660). The light curve shows a bright, hard initial pulse with a duration of ~0.170 ms, followed, after a short period of quiescence, by a weaker and softer emission episode lasing for ~16 s. Even more weaker and softer emission is traced in the KW light curve up to ~T0+90 s. The emission in the initial pulse is seen up to ~5 MeV. As observed by Konus-Wind, the burst had a total fluence of 1.62(-0.25, +0.49)x10^-5 erg/cm2 and a 16-ms peak energy flux, measured from T0, of (1.1 ± 0.1)x10^-4 erg/cm2 (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the initial pulse (measured from T0 to T0+0.192 s) is best fit in the 20 keV - 15 MeV range by a power law with exponential cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.01 (-0.14,+0.16), Ep = 887 (-88,+90) keV, chi2 = 46/55 dof. The time-averaged spectrum of the extended emission (measured from T0+0.256 to T0+16.640 s) is best fit in the 20 keV - 15 MeV range by the CPL model with alpha = -1.19 (-0.29,+0.35), Ep = 307 (-98,+342) keV, chi2 = 91/98 dof. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB170127_T05744/ All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.