//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10884 SUBJECT: GRB 100625A: Swift detection of a short hard burst DATE: 10/06/25 18:42:40 GMT FROM: David Palmer at LANL S. T. Holland (CRESST/USRA/GSFC), D. N. Burrows (PSU), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), W.B Landsman (GSFC), O. M. Littlejohns (U Leicester), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), A. Rowlinson (U Leicester), T. Sakamoto (NASA/UMBC), B. Sbarufatti (INAF-OAB/IASFPA), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC) and R. L. C. Starling (U Leicester) report on behalf of the Swift Team: At 18:32:28 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100625A (trigger=425647). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 15.771, -39.083 which is RA(J2000) = 01h 03m 05s Dec(J2000) = -39d 04' 57" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single peak with substructure with a duration of about 0.4 sec. The peak count rate was ~19,000 counts/sec (15-350 keV), at ~0.3 sec after the trigger. The XRT began observing the field at 18:33:16.7 UT, 48.3 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 15.79489, -39.08833 which is equivalent to: RA(J2000) = 01h 03m 10.77s Dec(J2000) = -39d 05' 18.0" with an uncertainty of 4.0 arcseconds (radius, 90% containment). This location is 70 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 2.15e+20 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 7.93e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 56 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 0.01. Burst Advocate for this burst is S. T. Holland (Stephen.T.Holland 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: 10885 SUBJECT: GRB100625A : MOA optical upper limit DATE: 10/06/25 21:19:35 GMT FROM: Suzuki Daisuke at MOA-II D. Suzuki, F. Hayashi, S. Kobara, T. Sako, H.Naito, K. Omori (STE Lab, Nagoya Univ.) on behalf of the MOA Collaboration report: We searched for an optical afterglow of GRB 100625A (GCN 10884, S. T. Holland et al.) starting from 18:49 UT on 2010 June 25th (17 minutes after the BAT trigger) with the MOA-II 1.8m telescope at Mt.John observatory in New Zealand. In a single image of a 60sec exposure with a wide-band Red filter (center wavelength ~ 750nm and FWHM ~ 250nm), we did not find any object within the error circle of the Swift XRT source position (GCN 10884). A 3 sigma upper limit is set in the I magnitude at 22.77 mag. This photometry was done by using the DoPhot and calibrated against the USNO-B1.0 catalog stars, and not corrected for the Galactic extinction. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10886 SUBJECT: GRB 100625A: Enhanced Swift-XRT position DATE: 10/06/26 04:51:36 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 646 s of XRT Photon Counting mode data and 1 UVOT images for GRB 100625A, 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 = 15.79574, -39.08842 which is equivalent to: RA (J2000): 01h 03m 10.98s Dec (J2000): -39d 05' 18.3" with an uncertainty of 1.8 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: 10887 SUBJECT: GRB 100625A: Gemini candidate afterglow DATE: 10/06/26 08:21:14 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick) and N.R. Tanvir (U. Leicester) report on behalf of a larger collaboration: "We observed the location of the short-hard GRB 100625A (Holland et al. GCN 10884) using Gemini-South and GMOS under poor conditions beginning at 06:50 UT. A total exposure time of 600s was obtained in the r-band. Within the refined XRT localisation (Goad et al. GCN 10886) we find a single source with r~23 (photometric calibration preliminary). The location of the source is: RA(J2000): 01:03:10.9 4 DEC(J2000): -39:05:18.7 with an error of approximately 0.5" in each axis. We suggest this may be the afterglow of GRB 100625A, however, given the poor seeing (2.5") we cannot distinguish between an afterglow or underlying host galaxy. Further observations are planned. We thank the staff of Gemini South, in particular Fredrik Rantakyro, for their assistance with these observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10888 SUBJECT: GRB 100625A: Swift-XRT Team refined analysis DATE: 10/06/26 08:34:27 GMT FROM: Kim Page at U.of Leicester K.L. Page (U. Leicester) and S. T. Holland (CRESST/USRA/GSFC) report on behalf of the Swift-XRT team: We have analysed 16 ks of XRT data for GRB 100625A (Holland et al. GCN Circ. 10884), from 61 s to 35.4 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN. Circ 10886). The light curve can be modelled with a power-law decay with a decay index of alpha=1.34 (+0.44, -0.26), with a small flare in the first orbit of data. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.34 (+0.31, -0.23). The best-fitting absorption column is consistent with the Galactic value of 2.1 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.2 x 10^-11 (3.6 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 1.34, the count rate at T+24 hours will be 1.1 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.5 x 10^-15 (3.9 x 10^-15) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00425647. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10889 SUBJECT: GRB 100625A : IRSF/SIRIUS NIR upper limit DATE: 10/06/26 10:13:17 GMT FROM: Hiroyuki Naito at Nagoya U H. Naito, T. Sako, D. Suzuki, S. Kobara and K. Omori (Nagoya Univ.) on behalf of the MOA Collaboration, T. Nagayama, M. Kurita (Nagoya Univ.) and N. Oi (The Graduate University for Advanced Studies/NAOJ) on behalf of the IRSF Collabration report: We searched for a NIR afterglow of the short GRB 100625A (S. T. Holland et al., GCN 10884) starting from 03:07:07 UT on 2010 June 26 with the SIRIUS on the IRSF 1.4m telescope at SAAO in South Africa. In images of a 20 min exposure with J, H and Ks filter, we did not find any object within the error circle of the Swift XRT source position (M. R. Goad et al., GCN 10886) and at the location of the Gemini source (A. J. Levan and N. R. Tanvir, GCN 10887). A 3 sigma upper limits are the followings. J > 19.37 H > 18.88 K > 18.02 This photometry was done by using the DoPhot and calibrated against the 2MASS cataloged stars. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10890 SUBJECT: Konus-Wind observation of GRB 100625A DATE: 10/06/26 10:28:51 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The short hard GRB 100625A (Swift-BAT trigger #425647: Holland et al., GCN 10884) triggered Konus-Wind at T0=66747.799 s UT (18:32:27.799). The burst light curve consists of two main peaks separated by ~100 ms, with a total duration of the burst of ~350 ms. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB100625_T66747/ As observed by Konus-Wind the burst had a fluence of 0.83(+/-0.15)x10-6 erg/cm2, and a 16-ms peak flux measured from T0 + 0.128s of 8.1(+/-1.5)x10-6 erg/cm2/s (both in the 20 keV - 2 MeV energy range). The time-integrated spectrum of the burst (from T0 to T0+0.192 s) is well fit in the 20 keV - 2 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), with alpha = -0.1(-0.5, +0.6), and Ep = 414(-78,+128) keV, chi2 = 18/18 dof. This spectrum is equally well fit in the same range by the GRB (Band) model, for which: the low-energy photon index alpha = +0.1 (+/-0.6), the high energy photon index beta = -2.6 ( <-1.9 ), the peak energy Ep = 371(-100,+135) keV, chi2 = 17/17 dof. All the quoted results are preliminary. All the quoted errors are at the 90% confidence level. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10891 SUBJECT: GRB 100625A: Swift-BAT refined analysis DATE: 10/06/26 14:34:54 GMT FROM: Michael Stamatikos at OSU/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), S. T. Holland (CRESST/USRA/GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU/NASA/GSFC), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+500 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100625A (trigger #425647) (Holland, et al., GCN Circ. 10884). The BAT ground-calculated position is RA, Dec = 15.796, -39.091 deg which is RA(J2000) = 01h 03m 11.1s Dec(J2000) = -39d 05' 29.3" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows two overlapping peaks starting at ~T-0.1 sec, peaking at ~T+0.1 and T+0.2 sec, and ending at ~T+0.3 sec. There is a weak soft tail out to ~T+30 sec. T90 (15-350 keV) is 0.33 +- 0.03 sec (estimated error including systematics). The time-averaged spectrum from T-0.1 to T+0.3 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 0.90 +- 0.10. The fluence in the 15-150 keV band is 2.3 +- 0.2 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.37 sec in the 15-150 keV band is 2.6 +- 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/425647/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10892 SUBJECT: GRB 100625A: Swift/UVOT Upper Limits DATE: 10/06/26 17:38:46 GMT FROM: Wayne Landsman at GSFC/SSAI W. Landsman (NASA/GSFC/Adnet) and S. Holland ((CRESST/USRA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100625A 56s after the BAT trigger (Holland et al., GCN Circ. 10884). No optical afterglow consistent with the enhanced XRT position (Page et al., GCN Circ. 10888) or the Gemini-South candidate afterglow position (Levan et al. GCN Circ. 10887) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag ----------------------------------------------- white 87 206 147 >21.2 (FC) u 269 519 246 >20.2 (FC) white 87 11552 785 >22.6 v 598 5951 412 >20.3 b 524 10640 1117 >21.9 u 269 6522 614 >20.5 w1 4725 6362 393 >20.6 m2 4520 6157 393 >20.5 w2 4111 12302 1125 >21.5 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.012 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10897 SUBJECT: GRB 100625A: Magellan near-IR Observations DATE: 10/06/28 16:41:19 GMT FROM: Edo Berger at Harvard E. Berger, R. Chornock, W. Fong (Harvard), W. Krzeminski (LCO), and G. Anglada (Carnegie/DTM) report: "We observed the location of the short GRB 100625A (GCN 10884) using the PANIC infrared imager on the Magellan/Baade 6.5-m telescope on 2010 June 27.39 UT (38.9 hours after the burst). A total of 1.75 hours were obtained in J-band in good seeing conditions (0.75 arcsec). Within the refined XRT error circle (GCN 10886) we detect a single object, coincident with the optical source detected by Levan et al. with Gemini about 12.3 hours after the burst (GCN 10887). In our combined image the object appears to be mildly extended. Given the continued detection of the object about 27 hours after the initial Gemini detection (with r~23 mag), and its extended nature, we consider this source to be a potential host galaxy." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10905 SUBJECT: GRB 100625A Gemini-South 2nd epoch imaging DATE: 10/06/29 11:36:34 GMT FROM: Nial Tanvir at IofA U.Cambridge N.R. Tanvir (U. Leicester) and A.J. Levan (U. Warwick) report on behalf of a larger collaboration: We re-observed the location of the short-hard GRB 100625A using GMOS on Gemini-South on 2010-06-28 beginning at 09:21 UT (approximately 63 hours post-burst). The source we previously identified within the XRT error circle (Levan et al. GCN 10887) is still detected with no obvious fading. We therefore concur with Berger et al. (GCN 10897) that this source, which is marginally extended, is a good candidate to be the host galaxy of the GRB. We thank the staff of Gemini South, in particular Fredrik Rantakyro, for their assistance with these observations. [GCN OPS NOTE(29jun10): Per author's request, the "North" in the Subject-line was changed to "South".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10906 SUBJECT: GRB100625A: GROND confirmation of constant source DATE: 10/06/29 14:01:16 GMT FROM: Paulo M. J. Afonso at MPE GRB 100625A: GROND confirmation of constant source A. Updike (Clemson University), P. Afonso and J. Greiner (both MPE Garching) report on behalf of the GROND team: We observed the field of the short-hard GRB 100625A, discovered by SWIFT(Holland et al., GCN 10884), simultaneously in g'r'i'z'JHK with GROND (Greiner et al.2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla Observatory (Chile). First epoch observations started at 06:13 UT on June 26, 10.7 hours after the GRB trigger, lasting for about 1 hour and done at high air mass. We took a second epoch starting at 09:29 UT on June 27 (~38 hrs after the trigger), lasting also for about 1 hour and done at seeing of ~ 2''. Within the enhanced XRT-position error circle (Good et al., GCN 10886) we detect a faint object at a position compatible with the Gemini-South candidate afterglow (Levan & Tanvir, GCN 10887). Based on stacked images with a total integration time of 49.6 min in g'r'i'z' and 40 min for JHK for each epoch, preliminary AB magnitudes (calibrated with GROND zero points) show that within the errors the object is constant between our two epochs. As suggested by the Magellan observations (Berger et al., GCN 10897) our results also point to the detection of a possible host galaxy. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10912 SUBJECT: GRB 100625A: Fermi GBM detection DATE: 10/06/30 12:55:57 GMT FROM: Narayana Bhat at U Alabama/Huntsville/GBM P. N. Bhat (UAH) reports on behalf of the Fermi GBM Team: "At 18:32:28.47 UT on 25 June 2010, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 100625A (trigger 299183550 / 100625773). which was also detected by the SWIFT-BAT(Holland et al. 2008, GCN 10884) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 125 degrees. The GBM light curve shows of 2 closely spaced narrow pulses with a duration (T90) of about 0.32 s (50-300 keV). The time-averaged spectrum from T0-0.128 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 -0.64 +0.12/-0.11 and the cutoff energy, parameterized as Epeak, is 509.2 +77.5/-61.5 keV (C-stat value 710 for 609 d.o.f.). The event fluence (8-1000 keV) in this time interval is (1.32 +/- 0.05)E-06 erg/cm^2. The 0.064-sec peak photon flux measured starting from T0-0.128 s in the 8-1000 keV band is 15.09 +/- 0.59 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."