///////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10336 SUBJECT: GRB 100117A: Swift detection of a short hard burst DATE: 10/01/17 21:19:26 GMT FROM: Scott Barthelmy at NASA/GSFC M. De Pasquale (UCL-MSSL), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), S. Campana (INAF-OAB), P.A. Curran (MSSL-UCL), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), V. Mangano (INAF-IASFPA), R. Margutti (Univ Bicocca&OAB), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), C. Pagani (PSU), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), T. Sakamoto (NASA/UMBC), B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 21:06:19 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100117A (trigger=382941). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 11.260, -1.594 which is RA(J2000) = 00h 45m 02s Dec(J2000) = -01d 35' 38" 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 0.4 sec. The peak count rate was ~4500 counts/sec (15-350 keV), at T_zero. The XRT began observing the field at 21:07:39.6 UT, 80.1 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 11.26946, -1.59620 which is equivalent to: RA(J2000) = 00h 45m 4.67s Dec(J2000) = -01d 35' 46.3" with an uncertainty of 4.6 arcseconds (radius, 90% containment). This location is 34 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 (2.66e+20 cm^-2, Kalberla et al. 2005), with an excess column of 4 (+3.65/-2.58) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 1.24e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 88 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 19.6 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 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. Burst Advocate for this burst is M. De Pasquale (mdp AT mssl.ucl.ac.uk). 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: 10337 SUBJECT: GRB100117A: Possible afterglow from NOT observation DATE: 10/01/17 23:14:51 GMT FROM: Dong Xu at DARK,NBI D. Xu (WIS, DARK/NBI), D. Malesani, G. Leloudas, J.P.U. Fynbo (DARK/NBI), A.A. Djupvik, R. Karjalainen (NOT), N.R. Tanvir (U. Leicester), P. Jakobsson (Univ. of Iceland) report on behalf of a larger collaboration: We observed the field of GRB100117A (De Pasquale et al., GCN 10336) with the Nordic Optical Telescope equipped with StanCam and NOTCam, starting at 21:26:40 UT on Jan 17th, 20.35 mins after the burst trigger. The observations were carried out at high airmass (~2) and in poor seeing. In a 900 s R-band image, starting at 21:48:42 UT, we notice the presence of a faint, marginally significant object at coordinates: RA(J2000)=00h 45m 04.75s Dec(J2000)=-01d 35' 47.4" with an error circle of 0.5 arcsec. If real, its magnitude is R = 22.5+/-0.5. The co-addition of a series of K-band images doesn't show any convincing counterpart on the position. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10338 SUBJECT: GRB 100117A: Swift-BAT refined analysis DATE: 10/01/17 23:45:29 GMT FROM: Scott Barthelmy at NASA/GSFC C. B. Markwardt (GSFC/UMD), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), M. De Pasquale (UCL-MSSL), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+484 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100117A (trigger #382941) (De Pasquale, et al., GCN Circ. 10336). The BAT ground-calculated position is RA, Dec = 11.280, -1.586 deg which is RA(J2000) = 00h 45m 07.1s Dec(J2000) = -01d 35' 11.1" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 66%. The mask-weighted light curve shows a single peak starting at T+0.0 and ending at T+0.4 sec. T90 (15-350 keV) is 0.3 +- 0.05 sec (estimated error including systematics). The time-averaged spectrum from T-0.0 to T+0.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.88 +- 0.22. The fluence in the 15-150 keV band is 9.3 +- 1.3 x 10^-8 erg/cm2. The 1-sec peak photon flux measured from T-0.35 sec in the 15-150 keV band is 2.9 +- 0.4 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/382941/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10339 SUBJECT: GRB 100117A: Gemini South Imaging and CFHT Pre-Explosion Images DATE: 10/01/18 02:06:23 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko, D. A. Perley, J. S. Bloom, B. E. Cobb, and A. N. Morgan (UC Berkeley) report on behalf of a larger collaboration: We have obtained pre-explosion images of the field of GRB100117A from the Canada-France-Hawaii MegaCam archive. Images were obtained in the g', r', and z' filters on 26 December 2005, and in the i' filter on 12 November 2007. Exposure times ranged from 240 s in g'-band to 500 s in i'-band. Inside the candidate XRT afterglow localization (de Pasquale; GCN 10336), we find four sources, with the following positions and R- and I-band magnitudes (calibrated relative to several USNO-B1 sources in the field; expected systematic uncertainty ~ 0.3 mag): Source RA Dec (J2000.0) R I ---------------------------------------------------------------------- S1 00:45:04.82 -01:35:47.7 23.1 21.0 S2 00:45:04.78 -01:35:45.5 23.6 22.9 S3 00:45:04.70 -01:35:42.0 24.5 22.9 S4 00:45:04.53 -01:35:49.2 > 24.7 23.6 We have also obtained a single epoch of acquisition imaging in i'-band of the field with GMOS on Gemini South beginning at 00:46 on 18 January 2010 (~ 4.7 hours after the burst). We detect only S1 in this image, at a magnitude consistent with the value derived from the CFHT image. Furthermore, given the uncertainty in our astrometry (~ 0.5" in each coordinate), we believe it likely this is the same source identified by Xu et al. (GCN 10337) at R = 22.5 +/- 0.5. We therefore have no evidence that this source has varied. Further observations are planned. We wish to thank the Gemini Observatory staff, in particular Peter Pessev, for assistance with these observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10340 SUBJECT: GRB 100117A: Magellan IMACS imaging DATE: 10/01/18 06:12:30 GMT FROM: Ryan Chornock at UC Berkeley R. Chornock, E. Berger (Harvard), R. Williams, and D. Kelson (OCIW) report: "We observed the location of the short GRB 100117A (GCN 10336) with IMACS on the Magellan/Baade 6.5-m telescope starting on 2010 Jan 18.042 UT (3.9 hours after the burst). In a 1200 sec stacked R-band image with a seeing of about 1" we detect the same four objects within the XRT error circle (GCN 10336) found in archival CFHT images by Cenko et al. and listed in GCN 10339. All four objects appear to be extended in our image, indicating that one of them may represent the GRB host galaxy. No new sources appear to be present within the XRT error circle, with a 3-sigma limiting magnitude of approximately R=24.7." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10341 SUBJECT: GRB 100117A: Gemini-North upper limit DATE: 10/01/18 07:31:14 GMT FROM: Antonino Cucchiara at PSU A. Cucchiara, D. B. Fox (PSU), E. Berger, R. Chornok (Harvard), A. Fruchter, J. Graham (STScI) report on a larger collaboration: "We observed the location of the short GRB 100117A (GCN 10336) with GMOS on the Gemini-North 8-m telescope starting on 2010 Jan 18.208 UT (7.9 hours after the burst). In a 2700 sec stacked r-band image with a seeing of about 1" we detect the same four objects within the XRT error circle (GCN 10336) found in archival CFHT images by Cenko et al. and listed in GCN 10339 (see also GCN 10340). As in the Magellan/IMACS image (GCN 10340) all four objects appear to be extended in the Gemini-North/GMOS data, indicating that one of them may represent the GRB host galaxy. No new sources appear to be present within the XRT error circle, with a 3-sigma limiting magnitude of approximately r=26.5." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10342 SUBJECT: GRB 100117A: Swift-XRT refined analysis DATE: 10/01/18 14:44:00 GMT FROM: Boris Sbarufatti at INAF-IASF-Pa B. Sbarufatti, R. Margutti (INAF/OAB) and M. De Pasquale (UCL-MSSL) report on behalf of the Swift-XRT team: We have analysed 5.5 ks of XRT data for GRB 100117A (De Pasquale et al. GCN Circ. 10336), from 69 s to 18.9 ks after the BAT trigger. The data comprise 180 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The best position is the SPER UVOT enhanced position: RA,Dec = 11.2690, -1.5949 (degrees) which is equivalent to: RA (J2000) = 00 45 4.56 Dec (J2000) = -01 35 41.7 with an uncertainty of 2.4 arcsec (radius, 90% containment). This location is 50.8 arcseconds from the BAT ground position, inside the BAT error circle. After the initial flaring activity the light curve can be modeled with a power-law decay with a decay index of alpha=3.5 (+/-0.2). The afterglow is not detected after the first snapshot of data (ending 500 s after the trigger), with an upper limit of 5E-3 count/sec at ~12 ks after the trigger The spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.6 (+/-0.13). The best-fitting absorption column is 1.2 (+/-0.4) x 10^21 cm^-2, in excess of the Galactic value of 2.7 x 10^20 cm^-2 (Kalberla et al. 2005). The observed (unabsorbed) 0.3-10 keV flux is 4.14 (4.84) x 10^-10 erg cm^-2 s^-1. The spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.3 (-0.5+0.6). The best-fitting absorption column is 1.1 (+1.3-0.9) x 10^21 cm^-2, slightly in excess of the Galactic value of 2.7 x 10^20 cm^-2 (Kalberla et al. 2005). The observed (unabsorbed) 0.3-10 keV flux is 2.40 (3.54) x 10^-12 erg cm^-2 s^-1. The count-rate to flux conversion factor is 6.0E-11 erg cm^-2 count^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00382941 . This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10343 SUBJECT: GRB 100117A: Optical object inside the revised XRT error circle DATE: 10/01/18 16:23:10 GMT FROM: Alexander Kann at TLS Tautenburg D. Alexander Kann (TLS Tautenburg), D. Malesani (DARK/NBI), D. Xu (WIS, DARK/NBI) report on behalf of a larger collaboration: Using the improved XRT position (B. Sbarufatti et al. GCN 10342) for the Swift short/hard GRB 100117A (M. de Pasquale et al., GCN 10336), we find that the afterglow candidate reported from NOT observations (D. Xu et al., GCN 10337), which is probably identical to source "S1" from S. B. Cenko et al. (GCN 10339), lies outside the error circle. We therefore consider it unlikely that this object is related to the GRB, also considering the lack of pronounced variability (S. B. Cenko et al. GCN 10339). Of the four sources reported by S. B. Cenko et al. (GCN 10339) and confirmed by R. Chornock et al. (GCN 10340) and A. Cucchiara et al. (GCN 10341), only source "S3" still lies within the new XRT error circle. Source S3, which is extended according to the above reports, may be the host galaxy of GRB 100117A, although lack of variability does not allow a conclusive statement. An additional image epoch to perform image subtraction is encouraged. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10344 SUBJECT: Swift/UVOT refined analysis of GRB100117A DATE: 10/01/18 18:00:20 GMT FROM: Massimiliano de Pasquale at MSSL-UCL M. De Pasquale (MSSL/UCL), S. T. Holland (NASA/GSFC), S. Oates (MSSL) report, on the behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100117A 89s after the BAT trigger (De Pasquale et al., GCN 10336). We do not detect any source in the UVOT-enhanced XRT error circle (Sbarufatti et al. GCN 10342) in the initial finding chart in the white filter, nor in the other filters. We do not detect the the S3 source of Cenko et al. (GCN 10339). UVOT magnitude 3-sigma upper limits are reported in the following table: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ------------------------------------------------------------- WHITE 89 238 147 > 20.4 WHITE 89 11957 1228 > 21.4 v 5589 17747 1082 > 19.8 b 557 6607 216 > 19.9 u 302 6402 442 > 19.9 uvw1 5999 18941 474 > 20.1 uvm2 5793 18652 1082 > 20.8 uvw2 5384 12757 978 > 20.9 No UVOT source has been found at the position of the NOT source (Xu et al., GCN 10337) outside the XRT error circle. The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight of E_(B-V) = 0.02 mag (Schlegel et al. 1998). All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10345 SUBJECT: GRB 100117A: Fermi GBM detection DATE: 10/01/18 19:14:16 GMT FROM: Bill Paciesas at UAH W. Paciesas (UAH) reports on behalf of the Fermi GBM Team: "At 21:06:19.66 UT on 17 January 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100117A (trigger 285455181 / 100117879) which was also detected by the Swift-BAT (De Pasquale et al. 2010, GCN 10336). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 86 degrees. The GBM light curve consists of one pulse with a duration (T90) of about 0.4 s. The time-averaged spectrum from T0-0.128 s to T0+0.256 s is adequately fit by a power law function with an exponential high energy cutoff. The power law index is -0.14 (+0.33 / -0.27) and the cutoff energy, parameterized as Epeak, is 287 (+74 / -50) keV (CSTAT 548 for 484 d.o.f.). The event fluence (8-1000 keV) in this time interval is (4.1 +/- 0.5 )E-07 erg/cm^2. The 0.256-sec peak photon flux measured starting from T0-0.128 s in the 8-1000 keV band is 6.1 +/- 0.4 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: 10346 SUBJECT: GRB 100117A: Gemini North spectroscopy DATE: 10/01/19 06:55:58 GMT FROM: Edo Berger at Harvard E. Berger, R. Chornock (Harvard), A. Cucchiara, D. B. Fox (PSU) report: "Starting on 2010 Jan 19.22 UT we used the GMOS spectrograph on the Gemini North 8-m telescope to obtain spectroscopic observations of several extended objects (GCNs 10339, 10340, 10341) located inside and near the revised XRT error circle (GCN 10342) of the short GRB 100117A (GCN 10336). The slit was aligned so that it covered sources S1, S2, and S3 (GCN 10339). Preliminary inspection of the combined 3000 sec spectrum covering the wavelength range 4000-8000 A reveals that source S1 is an M dwarf star. We detect continuum emission from sources S2 and S3 redward of about 5000 and 5600 A, respectively, but no clear emission or absorption features are identified." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10349 SUBJECT: GRB 100117A: candidate optical afterglow DATE: 10/01/19 20:04:13 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (Warwick), J. Graham, A. Fruchter (STScI), N. Tanvir (Leicester) A. Cucchiara, D. Fox (PSU), E. Berger, R. Chornock (Harvard) report for a larger collaboration: "We obtained a second epoch of Gemini North imaging of the short duration GRB 100117A (De Pasquale et al. GCN 10336) beginning at 06:17 UT. A total of 2700s of observations were acquired in the r-band. Comparison with our first epoch of observations (Cucchiara et al. GCN 10341) reveals that source S3 identifed by Cenko et al. (GCN 10339) has faded by 0.23 +/- 0.06 magnitudes in the timeframe between the two epochs of observation (approximately 25 hours). This is confirmed by image subtraction, which shows an offset from the centre of S3 by ~0.6". We suggest this is the afterglow of GRB 100117A. "