//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10484 SUBJECT: GRB 100316A: Swift detection of a burst DATE: 10/03/16 02:35:00 GMT FROM: Wayne Baumgartner at GSFC W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC), C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC), E. Troja (NASA/GSFC/ORAU), T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the Swift Team: At 02:23:00 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100316A trigger=416076). The BAT on-board calculated location is RA, Dec 252.032, +71.825 which is RA(J2000) = 16h 48m 08s Dec(J2000) = +71d 49' 31" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 10 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~2 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+51.8 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is W. H. Baumgartner (wayne 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: 10485 SUBJECT: GRB 100316A: Swift-XRT detection DATE: 10/03/16 04:12:35 GMT FROM: Andy Beardmore at U Leicester A.P. Beardmore, K.L. Page and O. Littlejohns (U. Leicester) report on behalf on the Swift-XRT team: Using 2.4ks of promptly downlinked data starting at 51.8 minutes after the trigger we find an uncatalogued X-ray source located at RA, Dec = 251.9789, 71.8265 which is equivalent to: RA (J2000.0) = 16 47 54.94 DEC (J2000.0) = +71 49 35.3 with an uncertainty of 4.53 arcsec (radius, 90% containment). It is not possible to tell whether the source is fading with the limited data available so far. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10486 SUBJECT: GRB 100316A: Swift/UVOT Observations DATE: 10/03/16 04:16:17 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and W. H. Baumgartner (GSFC/UMBC) report on behalf of the Swift/UVOT team: UVOT took a finding chart exposure of 150 seconds with the White filter starting 3200 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 (Beardmore et al., GCN Circ. 10485). 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 0.03. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10487 SUBJECT: GRB 100316 optical candidate from 1.23m CAHA telescope DATE: 10/03/16 04:22:03 GMT FROM: Javier Gorosabel at IAA-CSIC J. Gorosabel (IAA-CSIC), V. Peris (U. Valencia), P. Kubanek (IAA-CSIC, U. Valencia), report on behalf of a larger collaboration: "We have carried out R-band observations of the GRB100316 BAT error box (Baumgartner et al., GCN 10484) with the 1.23m telescope of Calar Alto. The observations started on March 16.1075 UT (11.7 min after the GRB). We detect an object with a rough magnitude of R~20.5 coincident with the XRT (GCN 10485) position and very likely not present on the DSS. Further observations are encouraged to determine the possible fading behaviour of this source. We propose that object as the potential optical afterglow of GRB100316." [GCN OPS NOTE(16mar10): Per author's request, the "Feb 16.1075" was changed to "March 16.1075".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10488 SUBJECT: GRB 100316 optical candidate from 1.23m CAHA telescope DATE: 10/03/16 05:16:37 GMT FROM: Javier Gorosabel at IAA-CSIC J. Gorosabel (IAA-CSIC), V. Peris (U. Valencia), P. Kubanek (IAA-CSIC, U. Valencia), report on behalf of a larger collaboration: "We have carried out R-band observations of the GRB100316 BAT error box (Baumgartner et al., GCN 10484) with the 1.23m telescope of Calar Alto. The observations started on Feb 16.1075 UT (11.7 min after the GRB). We detect an object with a rough magnitude of R~20.5 coincident with the XRT (GCN 10485) position and very likely not present on the DSS. Further observations are encouraged to determine the possible fading behaviour of this source. We propose that object as the potential optical afterglow of GRB100316." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10489 SUBJECT: GRB 100316B: Swift detection of a burst with optical counterpart DATE: 10/03/16 08:15:37 GMT FROM: Wayne Baumgartner at GSFC W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), S. Campana (INAF-OAB), P. A. Evans (U Leicester), J. M. Gelbord (PSU), C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC), O. M. Littlejohns (U Leicester), V. Mangano (INAF-IASFPA), C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester), C. Pagani (U Leicester), K. L. Page (U Leicester), P. Romano (INAF-IASFPA), A. Rowlinson (U Leicester), M. H. Siegel (PSU), R. L. C. Starling (U Leicester), G. Tagliaferri (INAF-OAB) and L. Vetere (PSU) report on behalf of the Swift Team: At 08:01:36 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100316B trigger=416103). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 163.498, -45.480 which is RA(J2000) = 10h 54m 00s Dec(J2000) = -45d 28' 47" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a multi-peaked structure with a duration of about 5 sec. The peak count rate was ~2500 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 08:02:41.1 UT, 64.1 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 163.48846, -45.47220 which is equivalent to: RA(J2000) = 10h 53m 57.23s Dec(J2000) = -45d 28' 19.9" with an uncertainty of 4.1 arcseconds (radius, 90% containment). This location is 36 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. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 9.92e+20 cm-2 (Kalberla et al. 2005). UVOT took a finding chart exposure of 150 seconds with the White filter starting 66 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 10:53:57.15 = 163.48812 DEC(J2000) = -45:28:21.6 = -45.47267 with a 90%-confidence error radius of about 0.62 arc sec. This position is 2.1 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.36 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.14. Burst Advocate for this burst is W. H. Baumgartner (wayne 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: 10490 SUBJECT: GRB 100316A: Enhanced Swift-XRT position DATE: 10/03/16 08:21:20 GMT FROM: Phil Evans at U of Leicester P.A. Evans reports on behalf of the Swift-XRT team Using 1129 s of XRT Photon Counting mode data and 2 UVOT images, 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 = 251.98150, 71.82780 which is equivalent to: RA (J2000): 16 47 55.56 Dec (J2000): +71 49 40.0 with an uncertainty of 2.9 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 is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10491 SUBJECT: GRB 100316C: Swift detection of a burst DATE: 10/03/16 09:12:15 GMT FROM: Michael Stamatikos at OSU/GSFC M. Stamatikos (OSU/NASA/GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), S. Campana (INAF-OAB), P. A. Evans (U Leicester), J. M. Gelbord (PSU), C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC), O. M. Littlejohns (U Leicester), R. Margutti (Univ Bicocca&OAB), C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester), C. Pagani (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), M. H. Siegel (PSU), R. L. C. Starling (U Leicester) and L. Vetere (PSU) report on behalf of the Swift Team: At 08:57:59 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100316C trigger=416115). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 32.291, -68.009 which is RA(J2000) = 02h 09m 10s Dec(J2000) = -68d 00' 31" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 7 sec. The peak count rate was ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 08:59:17.9 UT, 78.3 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 32.2869, -67.9914 which is equivalent to: RA(J2000) = 02h 09m 8.85s Dec(J2000) = -67d 59' 29.1" with an uncertainty of 2.4 arcseconds (radius, 90% containment). This location is 63 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 (3.94e+20 cm-2, Kalberla et al. 2005), with an excess column of 2.6 (+2.05/-1.79) x 1021 cm-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 81 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 overlap of the 8'x8' region for the list of sources generated on-board and the BAT error circle is uncertain. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04. Burst Advocate for this burst is M. Stamatikos (Michael.Stamatikos-1 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: 10493 SUBJECT: GRB 100316B: GROND Detection of the Optical/NIR Afterglow Candidate DATE: 10/03/16 10:11:25 GMT FROM: Robert Filgas at MPI P. Afonso, R. Filgas and J.Greiner (all MPE Garching) report on behalf of the GROND team: We observed the field of GRB 100316B (Swift trigger #416103; Baumgartner et al., GCN #10489) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile). Observations started at 08:17 UT on 16 March 2010, 16 minutes after the GRB trigger, and are continuing. We detect a single point source within the UVOT error circle reported by Baumgartner et al. Based on the first 4 min of total exposures in g'r', we estimate preliminary magnitudes (all in AB system) of g' = 19.2 +- 0.1 mag, r' = 18.9 +- 0.1 mag, indicating reshift < 3.5. Given magnitudes are calibrated against GROND zeropoints and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.14 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10494 SUBJECT: GRB 100316B: Skynet/PROMPT Observations of Fading DATE: 10/03/16 10:13:19 GMT FROM: Josh Haislip at U.North Carolina J. Haislip, K. Ivarsen, D. Reichart, A. LaCluyze, R. Egger, A. Foster, J. Moore, A. Oza, M. Schubel, J. Styblova, A. Trotter, J. A. Crain, and M. Nysewander report: Skynet observed the Swift/BAT localization of GRB 100316B (Baumgartner et al., GCN 10489) with four of the 16" PROMPT telescopes at CTIO beginning 32 seconds after the trigger (19 seconds after notification) in BVRI. We detect the afterglow (Baumgartner et al., GCN 10489) in all filters. At 34 seconds after the trigger, the afterglow's magnitude was I = 15.61 +0.16 -0.14 (statistical) +/- 0.20 (systematic; calibrated to 56 USNO B1 stars). Between 34 seconds and 2.1 minutes after the trigger, the afterglow faded with a power-law index of about -1.0. Between 2.1 and 35 minutes after the trigger, the afterglow faded more slowly, with a power-law index of about -0.3. Between 35 and 41 minutes after the trigger, the afterglow suddenly rebrightened, with a power-law index of about +5.4. Between 41 and 49 minutes after the trigger, the afterglow faded with a power-law index of about -0.6. Between 49 and 95 minutes after the trigger, the afterglow faded more rapidly, with a power-law index of about -1.7. At 95 minutes after the trigger, the afterglow's magnitude was R = 19.51 +0.33 -0.26 (statistical) +/- 0.28 (systematic; calibrated to 40 USNO B1 stars). Skynet's most recent BVRI light curve, calibrated to USNO B1 and NOMAD stars, can be found here: http://skynet.unc.edu/grb/grb100316b.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10495 SUBJECT: GRB 100316B: VLT/X-shooter redshift DATE: 10/03/16 11:04:59 GMT FROM: Paolo D'Avanzo at INAF-OAB S.D. Vergani (APC/Univ. Paris 7), P. D'Avanzo (INAF-OAB), D. Malesani, J.P.U. Fynbo, J. Hjorth (DARK/NBI), A.J. Levan (Univ. Warwick), H. Flores (Paris Obs.), N.R. Tanvir (Univ. Leicester), P. Goldoni (APC/Univ. Paris 7 and SAp/CEA), L.A. Antonelli (INAF-OAR) report on behalf of a larger collaboration: We observed the optical afterglow of GRB 100316B (Baumgartner et al., GCN 10489; Afonso et al. GCN 10493; Haislip et al., GCN 10494) with the VLT equipped with the X-shooter spectrograph. Observations started on 2010 Mar 16 at 08:43 UT (~ 40 minutes after the GRB), for a total exposure time of 4x600 s. From the acquisition image, we estimate for the optical afterglow a magnitude of R = 18.2 +- 0.1 (calibrated against USNO-B1.0). In a preliminary analysis of the specta, we clearly detect the continuum in the UVB, VIS, and NIR arms, corresponding to the wavelength range 3200-24000 AA. We detect several absorption features, among these FeII(1608), AlII(1670), AlIII(1854), FeII(2344), FeII(2374), FeII(2382), MgII(2796, 2803) and MgI(2852) at a common redshift of z=1.180. The lack of Lyman forest lines down to ~3200 AA sets an upper limit to the redshift z<1.6. We also find evidence for FeII lines and MgII doublet from a strong intervening systems at z=1.063. We caution that the above analysis (particularly the wavelength solution) is preliminary. Reduction with updated calibrations is underway. We would like to thank the ESO staff for their kind assistance, in particular Linda Schmidtobreick, Christophe Martayan, Patricia Guajardo and Manuel Olivares. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10496 SUBJECT: GRB 100316D: Swift detection of a burst DATE: 10/03/16 12:56:50 GMT FROM: Scott Barthelmy at NASA/GSFC M. Stamatikos (OSU/NASA/GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), S. Campana (INAF-OAB), A. de Ugarte Postigo (INAF-OAB), P. A. Evans (U Leicester), J. M. Gelbord (PSU), C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA), R. Margutti (Univ Bicocca&OAB), F. E. Marshall (NASA/GSFC), S. R. Oates (UCL-MSSL), C. Pagani (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/IASFPA), R. L. C. Starling (U Leicester) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 12:44:50 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100316D trigger=416135). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 107.615, -56.278 which is RA(J2000) = 07h 10m 28s Dec(J2000) = -56d 16' 40" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). This is an image trigger, but there is a possibility that there is a low-level peak about 100 sec long. The XRT began observing the field at 12:47:08.1 UT, 137.7 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 107.6291, -56.2567 which is equivalent to: RA(J2000) = 07h 10m 30.98s Dec(J2000) = -56d 15' 24.1" with an uncertainty of 5.0 arcseconds (radius, 90% containment). This location is 81 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 2.38e-09 erg cm-2 s-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 148 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. Because part of the 2.7'x2.7' sub-image was not received, the overlap with the XRT error circle is uncertain. The coverage of the XRT error circle by the 8'x8' region for the list of sources generated on-board is uncertain because the large number of sources filled the available telemetry. No correction has been made for the expected extinction corresponding to E(B-V) of 0.12. Burst Advocate for this burst is M. Stamatikos (Michael.Stamatikos-1 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: 10497 SUBJECT: GRB 100316C: BOOTES-3 observations DATE: 10/03/16 13:30:41 GMT FROM: Martin Jelinek at Inst.Astrophys.Andalucia,Granada M. Jelinek (IAA-CSIC), A. de Ugarte Postigo (INAF-OAB), A.J. Castro-Tirado (IAA-CSIC), J. Gorosabel (IAA-CSIC), P. Kubanek (IPL UV, IAA-CSIC), R. Cunniffe (IAA-CSIC), S. Guziy (IAA-CSIC), P. Yock (Auckland Univ.), W.H. Allen (Vintage Lane Obs.), I. Bond (Massey Univ.), G. Christie (Stardome Obs.), on behalf of a larger collaboration report: "We have observed the field of GRB 100316C (Stamatikos et al., GCN 10491) using the 0.6m Yock-Allen robotic telescope (BOOTES-3) located in Blenheim, New Zealand. Observations began at 8:58:47 UT (49s from GRB onset and 4 s from the GCN alert receipt). We do not detect any source within the XRT error circle in a 20 x 2 second combined unfiltered image down to a 3 sigma limiting magnitude of 18.5." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10499 SUBJECT: GRB100316A: Swift/UVOT Upper Limits DATE: 10/03/16 14:30:44 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL) and W. H. Baumgartner (GSFC/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100316A 3201s after the BAT trigger (Baumgartner et al., GCN Circ. 10484). We do not detect any source at the enhanced Swift XRT position (Evans et al. GCN Circ. 10490) and at the location of the candidate source detected by the CAHA telescope (Gorosabel et al. GCN Circ. 10487). The 3-sigma upper limits for the finding chart exposures (FC) and summed images are: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ------------------------------------------------------------- white (FC) 3201 3350 147 > 21.08 white 3770 5408 393 > 21.32 v 4182 16726 1210 > 20.48 b 3565 5203 393 > 20.79 u 3359 11527 1110 > 20.66 uvw1 4593 10786 1082 > 21.11 uvm2 4387 17306 1648 > 21.11 uvw2 3977 15812 1279 > 21.28 ------------------------------------------------------------- The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight of E_(B-V) = 0.03 mag. All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10500 SUBJECT: GRB 100316B: Swift-BAT refined analysis DATE: 10/03/16 15:54:41 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), 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-61 to T+242 sec from recent telemetry downlinks, we report further analysis of BAT GRB 100316B (trigger #416103) (Baumgartner, et al., GCN Circ. 10489). The BAT ground-calculated position is RA, Dec = 163.499, -45.464 deg, which is RA(J2000) = 10h 53m 59.8s Dec(J2000) = -45d 27' 49.3" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 83%. The mask-weighted light curve shows a FRED peak starting at T-0.3 sec, peaking at ~T+0.2 sec, and ending at ~T+20 sec. T90 (15-350 keV) is 3.8 +- 0.5 sec (estimated error including systematics). The time-averaged spectrum from T-0.4 to T+4.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.23 +- 0.18. The fluence in the 15-150 keV band is 2.0 +- 0.2 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-0.11 sec in the 15-150 keV band is 1.3 +- 0.1 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/416103/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10501 SUBJECT: GRB 100316A: Swift-BAT refined analysis DATE: 10/03/16 16:03:52 GMT FROM: Scott Barthelmy at NASA/GSFC W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), 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-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100316A (trigger #416076) (Baumgartner, et al., GCN Circ. 10484). The BAT ground-calculated position is RA, Dec = 251.953, 71.819 deg which is RA(J2000) = 16h 47m 48.8s Dec(J2000) = +71d 49' 09.5" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 16%. The mask-weighted light curve shows a FRED-like pulse starting at ~T-1 sec, peaking at ~t+2 sec, and ending at ~T+20 sec. T90 (15-350 keV) is 7.0 +- 0.9 sec (estimated error including systematics). The time-averaged spectrum from T-1.2 to T+6.7 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.46 +- 0.18. The fluence in the 15-150 keV band is 8.2 +- 0.9 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+1.94 sec in the 15-150 keV band is 2.3 +- 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/416076/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10502 SUBJECT: GRB 100316B: Enhanced Swift-XRT position DATE: 10/03/16 16:51:19 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 1148 s of XRT Photon Counting mode data and 2 UVOT images for GRB 100316B, 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 = 163.48865, -45.47244 which is equivalent to: RA (J2000): 10h 53m 57.28s Dec (J2000): -45d 28' 20.8" 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: 10503 SUBJECT: GRB 100316A: Swift-XRT refined analysis DATE: 10/03/16 17:21:12 GMT FROM: Andy Beardmore at U Leicester A. P. Beardmore (U. Leicester) and W. H. Baumgartner (GSFC/UMBC) report on behalf of the Swift-XRT team: Due to an Earth-limb constraint, Swift performed a delayed slew to GRB 100316A (Baumgartner et al. GCN Circ. 10484), with XRT observations starting 3.2 ks after the BAT trigger. The enhanced XRT position for this burst was given by Evans (GCN. Circ 10490). The X-ray light curve, obtained from 7.5 ks of Photon Counting (PC) mode data spanning 3.2 ks to 17.3 ks after the trigger, can be modelled by a power-law decay, with a decay slope of 1.3 +/- 0.3. An X-ray spectrum formed from the same data can be modelled by an absorbed power-law, with a photon index of 2.3 +0.3 -0.5 and absorbing column density of (1.5 +1.2 -1.1) x 10^21 cm^-2, which is in excess of the Galactic value of 4.4 x 10^20 cm^-2 (Kalberla et al. 2005) in the direction of the source. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.4 x 10^-11 (5.3 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay at the same rate, the count rate at T+24 hours will be 1.2 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.0 x 10^-14 (6.3 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00416076. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10504 SUBJECT: GRB 100316A: TAROT Calern observatory optical observations DATE: 10/03/16 18:09:07 GMT FROM: Bruce Gendre at ASDC Gendre B. (ASDC), Klotz A. (CESR-OMP), Boer M. (OHP-OAMP), Atteia J.L. (LATT-OMP) report: We imaged the field of GRB 100316A detected by SWIFT (trigger 416076, GCN 10484, Baumgartner et al. ) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. The observations started 1323s after the GRB trigger (1299s after the notice). The elevation of the field increased from 58 degrees above horizon and weather conditions were good. We obtained 16 image with clear filter and 8 images with R filter (see the description in Klotz et al., 2006, A&A 451, L39). We do not detect any OT within the exposures. Co-adding the images taken with clear filter, we can set a limiting magnitude of: R > 20.0 between t0+1323s to t0+3327s at the position of the candidate reported by Gorosabel et al. (GCN 10487) and Beardmore et al. (GCN 10485). Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon=103.8139 lat=+35.1341 and the galactic extinction in R band is 0.1 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10505 SUBJECT: GRB 100316D: Swift XRT refined analysis DATE: 10/03/16 18:32:59 GMT FROM: Rhaana Starling at U of Leicester R.L.C. Starling, P.A. Evans (U. Leicester) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift-XRT team: We have analysed the first orbit of Swift XRT data for GRB 100316D (Stamatikos et al. GCN Circ. 10496), comprising 593 s of exposure from 143 s to 737 s after the BAT trigger. The data are solely in Windowed Timing (WT) mode. The light curve over this time decays very slowly and can be modelled with a power-law with a decay index of alpha=0.13+/-0.03. A spectrum formed from these data can be fitted with an absorbed power-law with a photon spectral index of 1.42 (+/-0.04). The best-fitting absorption column is 5.9 (+/-0.3) x 10^21 cm^-2, in excess of the Galactic value of 7.0 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 6.6 x 10^-11 (8.7 x 10^-11) erg cm^-2 count^-1. If the decay contines with alpha=0.13, the predicted count rate at T+24h is 16 count s^-1 or an observed (unabsorbed) 0.3-10 keV flux of 1.1 (1.4) x10^-9 erg cm-2 s-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00416135. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10506 SUBJECT: GRB 100316C: Enhanced Swift-XRT position DATE: 10/03/16 18:52:07 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 1879 s of XRT Photon Counting mode data and 2 UVOT images for GRB 100316C, 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 = 32.28660, -67.99098 which is equivalent to: RA (J2000): 02h 09m 8.78s Dec (J2000): -67d 59' 27.5" 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: 10507 SUBJECT: GRB 100316C: Swift-XRT team refined analysis DATE: 10/03/16 19:15:43 GMT FROM: Kim Page at U.of Leicester K.L. Page (U. Leicester) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift-XRT team: We have analysed 5.7 ks of XRT data for GRB 100316C (Stamatikos et al. GCN Circ. 10491), from 87 s to 13.5 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 10506). The light curve can be modelled with a doubly-broken power-law, with alpha1 = 0.28 (+0.66,-1.18) until T = 258 (+87/-66) s after the trigger, at which point the decay steepens to alpha2 = 2.53 (+1.18, -0.44). At T = 883 (+1857, -271) s, the decay flattens to alpha3 = 0.76 (+0.27, -0.26). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.6 (+0.5, -0.4). The best-fitting absorption column is 1.8 (+1.6, -1.3) x 10^21 cm^-2, in excess of the Galactic value of 3.9 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 5.1 x 10^-11 (6.2 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 0.76, the count rate at T+24 hours will be 0.0013 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.6 x 10^-14 (8.1 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00416115. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10508 SUBJECT: GRB 100316B: Swift/UVOT observations DATE: 10/03/16 19:29:42 GMT FROM: Patricia Schady at MSSL/Swift S. R. Oates (MSSL-UCL) and W. H. Baumgartner (GSFC/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began observerving the field of GRB 100316B 67s after the BAT trigger (Baumgartner et al., GCN Circ. 10489). We detect the optical afterglow in the white, v, b, u and marginally in the uvw1 filter. The refined UVOT position is RA (J2000)= 163.48809, DEC (J2000)=-45.47265, which is equivalent to: RA (J2000) = 10:53:57.141 Dec (J2000) = -45:28:21.54 with an estimated uncertainty of 0.52 arcsec (radius, 90% confidence). This position is consistent with the XRT refined position (Beardmore et al., GCN Circ 10502). The marginal detection in the uvw1 filter is consistent with the VLT redshift upper limit (D'Avanzo et al., GCN Circ. 10495). Preliminary magnitudes and the 3 sigma upper limits are reported below for individual optical images and summed UV images. Filter T_start(s) T_stop(s) Exposure Mag Err ########################################################### white 67 216 147 18.36 +/- 0.05 white 857 1007 147 19.15 +/- 0.09 u 279 528 246 18.44 +/- 0.10 v 1212 1232 19 18.28 +/- 0.46 b 535 555 19 18.97 +/- 0.36 uvw1 659 1108 58 18.91 +/- 0.36 uvm2 634 1246 66 > 18.59 uvw2 585 1207 78 > 19.13 ########################################################### The above magnitudes are not corrected for the Galactic extinction corresponding to a non-negligible reddening of E_{B-V} = 0.14 mag (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383,627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10509 SUBJECT: GRB 100316C: Swift-BAT refined analysis DATE: 10/03/16 20:04:22 GMT FROM: Scott Barthelmy at NASA/GSFC D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), 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-60 to T+243 sec from recent telemetry downlinks, we report further analysis of BAT GRB 100316C (trigger #416115) (Stamatikos, et al., GCN Circ. 10491). The BAT ground-calculated position is RA, Dec = 32.309, -67.992 deg which is RA(J2000) = 02h 09m 14.2s Dec(J2000) = -67d 59' 30.3" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a roughly symmetric peak starting at ~T-3 sec, peaking at ~T+3 sec, and ending at ~T+12 sec. T90 (15-350 keV) is 9.3 +- 1.7 sec (estimated error including systematics). The time-averaged spectrum from T-3.0 to T+7.0 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.58 +- 0.26. The fluence in the 15-150 keV band is 1.8 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+2.12 sec in the 15-150 keV band is 0.4 +- 0.1 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/416115/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10510 SUBJECT: GRB100316C: Swift/UVOT Upper Limits DATE: 10/03/16 20:05:15 GMT FROM: Patricia Schady at MSSL/Swift S. R. Oates (MSSL-UCL) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100316C 81s after the BAT trigger (Stamatikos et al., GCN Circ. 10491). We do not detect any source at the enhanced Swift XRT position (Evans et al. GCN Circ. 10506). The 3-sigma upper limits for the finding chart exposures (FC) and summed images are: Filter T_start T_stop Exp(s) Mag (3-sigma upper limit) ------------------------------------------------------------- white (FC) 81 231 147 > 20.52 white 521 7450 677 > 21.63 u (FC) 239 489 246 > 19.87 u 644 7039 529 > 20.22 v 570 12991 1326 > 20.45 b 495 7245 549 > 20.72 uvw1 620 6834 333 > 20.24 uvm2 595 13530 741 > 20.60 uvw2 546 7656 471 > 20.57 ------------------------------------------------------------- The quoted upper limits have not been corrected for the expected Galactic extinction along the line of sight of E_(B-V) = 0.04 mag. All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10511 SUBJECT: GRB 100316D: Swift-BAT refined analysis DATE: 10/03/16 23:16:32 GMT FROM: Scott Barthelmy at NASA/GSFC T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the telemetry downlinks, we report further analysis of BAT GRB 100316D (trigger #416135) (Stamatikos, et al., GCN Circ. 10496). The BAT ground-calculated position is RA, Dec = 107.599, -56.275 deg, which is RA(J2000) = 07h 10m 23.8s Dec(J2000) = -56d 16' 28.9" with an uncertainty of 3.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 85%. The mask-weighted light curve is relatively flat. The emission started before T-80 sec when the location came into the BAT FoV during a Swift planned-target slew. Using the event-by-event data, the lightcurve conitinue through the 64-sec integration of the image trigger and out to at least T+240 sec. Using the on-board mask-weighted lightcurve, the lightcurve continues out to at least T+740 sec where the data ends. The time-averaged spectrum using just the T+0.0 to T+64.0 sec image-trigger interval is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.29 +- 0.41. The fluence in the 15-150 keV band is 3.0 +- 0.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.00 sec in the 15-150 keV band is 0.1 +- 0.0 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/416135/BA/ We note that this lightcurve is very non-typical for a GRB and that the spectrum is soft. This is similar both in the temporal and spectral properties to the GRB060218-SN2006aj burst (Camapana, et al.; Nature, v224, p1008, Figure 1). In the 060218 burst, the BAT lightcurve was flat from T-50 to T+300 sec. The X-ray temporal decay (Starling, GCN Circ 10505) is shallow as it was in SN2006aj (Campana, Fig 1). We further note that the 5 arcsec XRT error circle (GCN 10496) covers the edge of an extended object (a pair of unresolved stars or a galaxy) in DSS. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10512 SUBJECT: GRB 100316D: VLT/X-shooter observations DATE: 10/03/17 03:05:25 GMT FROM: Paolo D'Avanzo at INAF-OAB S.D. Vergani (GEPI-Obs. Paris), P. D'Avanzo (INAF-OAB), A.J. Levan (Univ. Warwick), S. Covino (INAF-OAB), D. Malesani, J. Hjorth (DARK/NBI), L.A. Antonelli (INAF-OAR) report on behalf of a larger collaboration: We observed the field of GRB 100316D (Stamatikos et al., GCN 10496) with the VLT equipped with the X-shooter spectrograph. Observations started on 2010 Mar 17 at 00:58 UT (~ 12 hours after the GRB). In the 100s acquisition image, we detect an object inside the XRT error circle, at the following position (J2000): RA: 07:10:30.77 Dec: -56:15:20.7 (+/- 0.5"). The object has a magnitude R~21 (calibrated against USNO-B1.0) and is very close (~3.5") to the DSS galaxy reported by Sakamoto et al. (GCN 10511). In the X-shooter spectrum of this source we detect several bright emission lines. Among these we have [OII], Hdelta, Hgamma, Hbeta, [OIII], Halpha all at a common redshift of 0.059. At present, we cannot say if this object (that might be a region of the nearby galaxy) is related with GRB 100316D. Further analysis and observations are in progress. We caution that the above analysis (particularly the wavelength solution) is preliminary. Reduction with updated calibrations is underway. We would like to thank the ESO staff for their kind assistance, in particular Thomas Rivinius, Alvaro Alvarez and Andres Pino //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10513 SUBJECT: GRB 100316D: Gemini/GMOS and VLT/X-shooter observations DATE: 10/03/17 04:37:46 GMT FROM: Paolo D'Avanzo at INAF-OAB S.D. Vergani (GEPI-Obs. Paris), A.J. Levan (Univ. Warwick), P. D'Avanzo (INAF-OAB), S. Covino (INAF-OAB), D. Malesani, J. Hjorth (DARK/NBI), N.R. Tanvir (Univ. Leicester), L.A. Antonelli (INAF-OAR) report on behalf of a larger collaboration: We carried out further observations of the field of GRB 100316D (Stamatikos et al., GCN 10496) with the Gemini telescope equipped with GMOS in imaging mode (~ 12 hours after the GRB). Inside the XRT error circle we detect two discrete, compact objects, both of which lie on the stellar field of the DSS galaxy (Sakamoto et al. GCN 10511; Vergani et al. GCN 10512): Object A: RA (J2000): 07:10:30.77 Dec (J2000): -56:15:20.7 Object B: RA (J2000): 07:10:30.48 Dec (J2000): -56:15:22.3 Both position have errors of approximately 0.5" in each axis. We note that object "A" is the same reported by Vergani et al. (GCN 10512). We obtained a VLT/X-shooter spectrum of source "B", which exhibits the same emission lines reported by Vergani et al. (GCN 10512) for object "A" at the same redshift of z=0.059. Likely, object "A" and "B" are regions of the nearby DSS galaxy. A finding chart is available at the following web page: http://www.astro.ku.dk/~malesani/GRB/100316D/GRB100316D_finder.png We caution that the above analysis (particularly the wavelength solution) is preliminary. Reduction with updated calibrations is underway. We would like to thank the Gemini staff for their kind assistance, in particular Rodrigo Carrasco. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10514 SUBJECT: GRB 100316D: GROND Detection of the Optical/NIR Afterglow Candidate DATE: 10/03/17 04:47:13 GMT FROM: Adria C. Updike at Clemson U Paulo Afonso (MPE Garching), Adria Updike (Clemson University), Marco Nardini, Robert Filgas, Abdullah Yoldas, and Jochen Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 100316D (Swift trigger 416135; Stamatikos et al., GCN 10496) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile). Observations started at 00:28 UT on March 17, 11.66 hours after the GRB trigger, and are continuing. They were performed at an average seeing of 1" and at an average airmass of 1.1. We detect what appears to be a bright point on the edge of the extended object noted by Sakamoto et al. (GCN 10511) within the XRT error circle. This is consistent with the source identified by Vergani et al. (GCN 10512). The source is detected in all bands, suggesting a redshift < 3.5. We cannot yet determine if this source is related to the GRB. Further observations are required to establish variability, and to check whether the optical bands show similarities to GRB 060218 - SN 2006aj as reported by Sakamoto et al. (GCN 10511) for the gamma ray and x-ray bands. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10516 SUBJECT: GRB 100316C: GROND Detection of a Optical/NIR Afterglow Candidate DATE: 10/03/17 05:41:37 GMT FROM: Adria C. Updike at Clemson U Paulo Afonso (MPE Garching), Adria Updike (Clemson University), Marco Nardini, Robert Filgas, Abdullah Yoldas, and Jochen Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 100316C (Swift trigger 416115; Stamatikos et al. GCN 10491) simultaneously in g'r'i'z' JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile). Observations started at 00:45 UT on March 17, 2010, 15.8 hours after the GRB trigger, and are continuing. They were performed at an average seeing of 1" and at an average airmass of 2. We found a DSS uncataloged source at the edge of the 1.8 Swift-XRT error circle reported by Evans et al. (GCN 10506) at RA (J2000.0) = 02 h 09 m 09.11 s DEC (J2000.0) = -67d 59' 26.8" with an uncertainty of 0.5" in each coordinate. Based on the first 31 min of total exposures in g'r'i'z', we estimate preliminary magnitudes (all in AB system) of g' = 23.7 +/- 0.1 mag, r' = 24.4 +/- 0.1 mag, i' > 23.6 mag, z' > 23.9 mag. Further observations are necessary to confirm variability. If this is indeed the afterglow of GRB 100316C, the colors indicate a redshift less than 3.5. Given magnitudes are calibrated against GROND zeropoints and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.03 mag in the direction of the burst (Schlegel et al. 1998). JHK reduction is ongoing. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10517 SUBJECT: Tentative redshift of GRB100316D from X-ray data DATE: 10/03/17 06:37:22 GMT FROM: Sergio Campana at INAF-OAB S. Campana (INAF-OAB) reports on behalf of the Swift-XRT team: Swift XRT observed GRB 100316D (Stamatikos et al. 2010, GCN10496) in Windowed Timing (WT) mode in the 144-737 s time interval. During this interval the light curve decays very slowly (decay index alpha=-0.13, Starling et al. 2010, GCN 10505). In addition, the 1.5-10 keV to 0.3-1.5 keV hardness ratio remains constant (reduced chi2=0.91 with 97 degrees of freedom, dof). Motivated by the high count rate (around 30 c s^-1, but far from the pile up limit) and by the constant spectral shape we tried to estimate the GRB redshift from the X-ray data. We assume a Galactic column density of 7x10^20 cm^-2 (Kalberla et al. 2005, A&A 440 775) and fit the WT spectrum taken from the Leicester pages (http://www.swift.ac.uk/xrt_spectra/00416135/) with an absorbed (phabs*zphabs) cutoff power law model (the cutoff power law model provides much better results in terms of column density evaluation with respect to a simple power law model when small spectral variations are present). Given the high count rate we selected single pixel events only. The resulting fit is good (reduced chi2=1.2, 333 dof). The redshift is constrained to lie within the 90% confidence level (delta chi2=4.61) of 0.014 O. M. Littlejohns, P. A. Evans, K. L. Page (U. Leicester) and W. H. Baumgartner (GSFC/UMBC) report on behalf of the Swift-XRT team: We have analysed 2.9 ks of XRT data for GRB 100316B (Baumgartner et al. GCN Circ. 10489), from 75 s to 40.1 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN. Circ 10502). The light curve can be modelled with a broken power-law decay with an initial decay index of alpha=0.1 (+/-0.2), followed by a break at T~1100 s to a final decay of alpha=1.2 (+0.5, -0.1). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.35 (+0.24, -0.21). The best-fitting absorption column is 4.1 (+2.7, -1.3) x 10^21 cm^-2, at a redshift of 1.18 (Vergani et al. GCN Circ 10495), in addition to the Galactic value of 9.9 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 3.4 x 10^-11 (5.8 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 1.2, the count rate at T+48 hours will be 6.6 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.2 x 10^-14 (3.8 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00416103. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10519 SUBJECT: GRB 100316D: Swift XRT enhanced position and further refined analysis DATE: 10/03/17 13:42:03 GMT FROM: Rhaana Starling at U of Leicester R.L.C. Starling, P.A. Evans (U. Leicester) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift XRT team: We have now analysed the first 3 orbits of Swift XRT data for GRB 100316D (trigger=416135, Stamatikos et al. GCN Circ. 10496), comprising 8 s of Windowed Timing (WT) settling mode data, 593 s of WT mode data and 3.7 ks of Photon Counting (PC) mode data. The early light curve is flat and can be modelled with a power-law decay with a decay index of alpha=0.13+/-0.03 as described in Starling et al. (GCN Circ. 10505). This now breaks at some time after T+750 s to a steeper decay of alpha=2.0 +0.3/-0.1. Using 1967 s of XRT Photon Counting mode data and 1 U-band UVOT image, 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 = 107.62763, -56.25547 which is equivalent to: RA (J2000): 07h 10m 30.63s Dec (J2000): -56d 15' 19.7" with an uncertainty of 3.7 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). We note that this position is 1.5 arcsec from the optical/nIR candidate 'Object A' reported in the VLT/X-Shooter and Gemini/GMOS observations by Vergani et al. (GCN Circ. 10513) and GROND observations reported by Afonso et al. (GCN Circ. 10514), and 2.9 arcsec from the candidate 'Object B' reported in GCN Circ. 10513. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10520 SUBJECT: GRB 100316D: Swift/UVOT Observations DATE: 10/03/17 16:54:15 GMT FROM: Samantha Oates at MSSL S. R. Oates (MSSL-UCL), M. De Pasquale (MSSL-UCL) and M. Stamatikos (OSU/NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 100316D 148s after the BAT trigger (Stamatikos et al., GCN Circ. 10496). Coincident with the refined Swift XRT error circle (Starling et al. GCN Circ. 10519), we detect the DSS galaxy, which hosts the sources A and B (Vergani et al. GCN Circ. 10512, 10513), but we are unable to resolve it. Our photometry, performed on 3ks of data in the 7 UVOT filters, shows no change larger than 1 sigma in the flux of this DSS galaxy. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10521 SUBJECT: GRB 100316A: optical observations in CrAO DATE: 10/03/18 01:23:18 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of the Swift GRB 100316A (Baumgartner et al. GCN 10484) with Shajn telescope of CrAO starting (UT) March 16 19:15 under descending weather conditions and mean seeing of 2 arcsec. No object is detected in enhanced XRT error circle (Evans, GCN 10490). The upper limit of point like object in a stacked image based on USNO-B1.0 star 1618-0120609 (J2000) RA= 16:48:06.44 Dec= +71:50:15.2 (assuming R2=15.25) is following: T0+ Filter, Exposure, mag. (mid, d) (s) 0.7061 R 8x60 > 21.6 The non-detection is strongly support the object of R~20.5 reported in GCN 10487 (Gorosabel et al) is the optical afterglow of GRB100316A. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10523 SUBJECT: GRB 100316D: Further Gemini observations DATE: 10/03/18 02:55:05 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), P. D'Avanzo (INAF-OAB), S.D. Vergani (GEPI-Obs. Paris), D. Malesani (DARK/NBI) report for a larger collaboration. "We re-observed the location of GRB 100316D (Stamatikos et al. GCN 10496; Starling et al. GCN 10519) using Gemini/GMOS in the r-band. Observations began at 23:55 UT, approximately 36 hours after the GRB, and 24 hours after our first epoch (Vergani et al. GCN 10513). The seeing in the second epoch is slightly worse than the first (0.9" versus 0.7") and so the resulting images are slightly shallower. No obvious objects within the refined XRT error circle (Starling et al. GCN 10519) show significant (>3 sigma) evidence for variation. However, we do note the presence of a previously unreported compact source that is within the X-ray error circle, but is close to the nucleus of the galaxy, at RA(J2000) = 07:10:30.54 Dec(J2000) = -56:15:20.0 This source is brighter than those previously discussed in GCN 10513 (R~20) but again, given the difficulty of performing accurate photometry against a bright and varying background of the host, we can't as yet make any firm statements about variability. We note, it is of course possible that a brightening supernova component and fading afterglow are conspiring to mask variability between these two epochs, and further observations are planned. We thank the staff of Gemini, in particular Rodrigo Carrasco for their help in executing these observations." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10524 SUBJECT: GRB 100316D: Pre-burst emission measured by BAT DATE: 10/03/18 21:13:59 GMT FROM: Takanori Sakamoto at NASA/GSFC T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), M. Stamatikos (GSFC/OSU) (i.e. the Swift-BAT team): Using the BAT hard X-ray survey data (Detector Plane Histogram data), we have processed the BAT survey data for pre- and post-trigger periods using the batsurvey script and have extracted the flux at the location of the GRB. While Swift was pointing at GRB 100316C from T-2650 s to T-80 s, the GRB 100316D location was in the FOV of BAT. At 12:43, Swift slewed to a pre-planned target (1E 1048.1-5937), and triggered on GRB 100316D. After re-pointing to the location of GRB 100316D, Swift slewed away from GRB 100316D at T+750 s due to an observational constraint. GRB 100316D came back into the FOV of BAT at T+5050 s (a pre-planned observation of 1E 1048.1-5937). The BAT light curve in the 14-195 keV band around the trigger time is available at: -Light curve from T-6000 sec to T+6000 sec: http://gcn.gsfc.nasa.gov/other/GRB100316D_bat_lc.gif -Zoom-in light curve from T-2000 sec to T+1000 sec: http://gcn.gsfc.nasa.gov/other/GRB100316D_bat_lc_zoomin.gif The light curve produced by the BAT event-by-event data is overlaid with the survey light curve in the figure. There is a probable early low-level emission starting from T-1500 s. The emission then rises at T-500 s, peaks at T-100 s, and decays with an exponential decay constant of ~750 s. The emission continues through the slew at T+750 s. The emission is no longer detected by BAT after T+5050 s. As pointed out in Sakamoto et al. (GCN Circ. 10511), the BAT light curve profile of GRB 100316D is very similar to the GRB 060218-SN2006aj burst (Camapana, et al.; Nature, v224, p1008). The BAT light curve of GRB 060218 shows a rise at T-300 s, a peak at T+450 s, and an exponential decay constant of ~500 s, with a duration of ~2000 sec. GRB 100316D was detected in Swift-BAT from ~T-500 sec to at least ~T+800 sec, hence the lower limit on the duration of GRB 100316D is ~1300 sec. The fluence in the 15-150 keV band measured with the available 955 seconds of event data is 3.4 x 10^-6 erg/cm2. This corresponds to an isotropic equivalent energy (Eiso) of 3.1x10^49 ergs in the 15.88 keV - 158.85 keV band at the GRB rest frame assuming a redshift z=0.059 of a potential source and a galaxy inside the XRT error circle (Vergani et al. GCN Circ. 10512, 10513). This unusually long duration in concert with a soft spectrum and a low Eiso (Eiso of GRB 060218 was 6.2x10^49 ergs) strengthens the similarity between GRBs 100316D and 060218. Although the lack of a clear optical counterpart to GRB 100316D at this stage is distinctly different than GRB 060218, the prompt emission characteristics are very much like supernova-associated GRB 060218. Hence, we suggest additional follow-up observations especially in the IR that may confirm the presence of a host supernova. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10525 SUBJECT: GRB 100316D: Possible Supernova DATE: 10/03/19 12:32:17 GMT FROM: Andrew Levan at U.of Leicester K. Wiersema (U. Leicester), P. D'Avanzo (INAF-OAB), A.J. Levan (U. Warwick), N.R. Tanvir (U. Leicester), D. Malesani (DARK/NBI), S. Covino (INAF-OAB) report for a larger collaboration: "We obtained a third epoch of observations of the localization of GRB 100316D (Stamatikos et al. GCN 10496; Starling et al. GCN 10519) using Gemini South and GMOS. Observations began at 23:48 UT on March 18, and were obtained in the r-band under excellent seeing (0.5"). Image subtraction reveals that the source previously identified by Levan et al (GCN 10523), has brightened between the two observations by ~0.3 magnitudes. We suggest that this object represents the rising supernova associated with GRB 100316D. Images of the field, and the subtraction can be found at http://www.star.le.ac.uk/~anl/100316D Further observations are planned. We thank the staff of Gemini for their help in executing these observations" //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10533 SUBJECT: GRB 100316D: ATCA radio observations DATE: 10/03/20 15:52:22 GMT FROM: Alicia Soderberg at Harvard/CfA Mark Wieringa (CSIRO), Alicia Soderberg (Harvard/CfA), and Phil Edwards (CSIRO) report: "We observed the field of GRB 100316D (Stamatikos et al. GCN 10496) with the Australia Telescope Compact Array beginning on Mar 18.35 for 3.5 hrs. Data were collected at central frequencies of 5.4 and 9.0 GHz with 2 GHz bandwidth each. We do not detect any radio sources within the refined XRT error circle (Starling et al. GCN 10519). We place upper limits of 104 microJy at 5.4 GHz and 165 microJy at 9.0 GHz (4 sigma). At the redshift of the host galaxy (z=0.059; Vergani et al. GCN 10512), these limits imply a radio spectral luminosity below 8e+27 erg/s/Hz which is a factor of 2 to 10 lower than the radio afterglow luminosities observed for nearby long-duration GRBs 980425 (Kulkarni et al. 1998), 031203 (Soderberg et al. 2004), and 060218 (Soderberg et al. 2006) on comparable timescales. Further observations are planned." //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10541 SUBJECT: GRB 100316D: Spectroscopic Discovery of a Supernova from Magellan DATE: 10/03/22 22:19:26 GMT FROM: Ryan Chornock at UC Berkeley R. Chornock, A. M. Soderberg, R. J. Foley, E. Berger, A. Frebel, P. Challis (Harvard/CfA), J. D. Simon, and S. Sheppard (Carnegie) report: We have been obtaining nightly spectra of GRB 100316D (Stamatikos et al., GCN 10496) with the MagE, LDSS3, and IMACS spectrographs on the twin 6.5-m Magellan telescopes, starting on 2010 March 18.0 UT, approximately 1.5 days after the BAT trigger. All spectra included the variable point source found by Levan et al. (GCN 10523) and Wiersema et al. (GCN 10525) within the slit aperture. All spectra show superposed high-equivalent-width nebular emission lines at z=0.059, in agreement with Vergani et al. (GCN 10512). Our earliest spectra show a very blue continuum with a few weak stellar features indicative of some starlight from a young stellar population falling within our spectroscopic aperture, but no other obvious features. By the time of our most recent MagE spectrum, from March 22.0 UT (T0+5.5 days), a few broad undulations in the continuum have developed, although contamination from the galaxy light and possibly an afterglow remains significant. The strongest feature has a flux peak near 7850 Angs (in the rest frame) and a minimum near 7280 Angs. An additional local minimum in the continuum is located near 5700 Angs with a broad maximum located to the red of that. The appearance of undulations in the spectrum near the expected locations of supernova features from a comparison with SN 1998bw at early times (while no such undulations appear in our earliest spectra) leads us to conclude that we have spectroscopically determined that the transient source which was detected photometrically (Wiersema et al., GCN 10525) is a supernova. A plot of an early and a recent spectrum compared to SN 1998bw can be found here: http://www.cfa.harvard.edu/~eberger/grb100316d-mage.pdf //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10543 SUBJECT: Emerging Supernova in the Afterglow of GRB 100316D DATE: 10/03/24 13:37:52 GMT FROM: Filomena Bufano at INAF-Osb Astro di Padova F. Bufano, S. Benetti, E. Cappellaro, INAF Osservatorio Astronomico di Padova (INAF-OAPd); S. Covino, INAF Osservatorio Astronomico di Brera (INAF-OABr); S. Vergani, P.Goldoni, GEPI (Observatoire de Paris) - APC (Université Paris 7); M. Della Valle, INAF Osservatorio di Capodimonte; E. Pian, INAF Osservatorio Astronomico di Trieste; S. Campana, G.Tagliaferri, INAF-OABr; D.Malesani, J. Fynbo, Dark Cosmology Centre; M. Turatto, INAF Osservatorio Astronomico di Catania; F.Patat, European Southern Observatory (ESO) and P. Mazzali, INAF-OAPd report on behalf of a larger colaboration that a high-dispersion optical spectrum (range 350-900 nm, resolution 0.02 nm) of the afterglow associated to GRB 100316D (cf. GCN 10496) was obtained with the VLT telescope (+XShooter) at ESO-Paranal on March 23.04 UT. The spectrum of the source located at R.A.=07:10:31.8 and Decl.=-56:15:20.2, J2000.0 (as measured on the XShooter acquisition image) shows very broad bumps with peaks measured at about 430nm and 670nm reminiscent of an emerging broad line type Ic supernova (in agreement with Chornock et al, GCN 10541). Indeed, above 600 nm the spectrum of this source shows some similarities with that of SN 1998bw (Patat et al. 2001, ApJ, 555, 900) taken 7 days after outburst. There are however major differences with the spectrum of this transient, showing a significant flux deficiency in the range 450-550nm in comparison with SN 1998bw . [GCN OPS NOTE(24mar10): Per author's request, the parenthetical comment "(in agreement with Chornock et al, GCN 10541)" was added.] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10547 SUBJECT: GROND observations of GRB100316D/SN2010bh DATE: 10/03/26 22:58:43 GMT FROM: Arne Rau at MPE Arne Rau, Marco Nardini (both MPE Garching), Adria Updike (Clemson University), Robert Filgas, Jochen Greiner, Thomas Kruehler (all MPE Garching), and Sylvio Klose (TLS Tautenburg) report on behalf of the GROND team: We report on additional observations of the field of GRB 100316D (Swift trigger 416135; Stamatikos et al., GCN 10496) 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). Observations started on 17 March 2010 at 00:27 UT, 11.7 hours after the burst (Afonso et al., GCN Circular #10514). The field was observed during additional 16 epochs and observations are continuing. Image subtraction revealed the supernova SN2010bh reported by Wiersema et al. (GCN Circular #10525), Chornock et al. (GCN Circular #10541), and Bufano et al. (GCN Circular #10543) to emerge approx. 5 days post-burst and to reach an AB magnitude of r ~ 18.8 +/- 0.2 at 7.5 days post-burst. The observed light curve evolution of SN2010bh is similar to that of SN1998bw (Galama et al. 1998), the supernova associated with GRB980425, shifted to the redshift of GRB100316D (z=0.059; Vergani et al., GCN Circular #10512). The optical luminosity is comparable to SN1998bw, except in the g-band, where the flux is suppressed by approx. 30%. This likely corresponds to the significant flux deficiency in the range 450-550nm reported from the X-Shooter spectrum (Bufano et al., GCN Circular #10543). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 10565 SUBJECT: GRB 100316A: R-band limit DATE: 10/04/02 12:51:11 GMT FROM: Myungshin Im at Seoul Nat U Jang, M., Im, M. (SNU), and Y. Urata (NCU) report on behalf of the EAFON collaboration: We observed GRB100316A in R-band starting at 2010 March16, 08:09:17UT, or 20.78 ks after the BAT triggered (Baumgartner et al, GCN 10484), using the 1.0m telescope at Mt.Lemmon in Arizona, U.S. operated by Korea Astronomy Space Science Institute. No afterglow candidate was detected from a stacked image of eight 300s-frames. within the error circle of the enhanced XRT position (Evans et al.,GCN 10490). We estimate the 3-sigma limiting magnitude of the afterglow to be R ~ 22.0 +/- 0.2 at the midpoint time of the stacked image (~T0+21.98 ks) by calibrating it against sixteen USNO-B1 stars near the GRB, using their R2 magnitudes without correcting for the Galactic extinction. Our limit indicates fading of the optical afterglow candidate reported by Gorosabel et al. (GCN 10488) shortly after. We thank the LOAO operator, I. Baek for her help with the observation