//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8227 SUBJECT: GRB 080915: Swift detection of a burst DATE: 08/09/15 00:14:56 GMT FROM: David Palmer at LANL S. R. Oates (UCL-MSSL), A. P. Beardmore (U Leicester), J. R. Cummings (NASA/UMBC), P. A. Evans (U Leicester), C. Gronwall (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL), A. M. Parsons (GSFC), R. L. C. Starling (U Leicester) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 00:02:49 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080915 (trigger=324744). The BAT on-board calculated location is RA, Dec 18.004, -76.014 which is RA(J2000) = 01h 12m 01s Dec(J2000) = -76d 00' 51" 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 20 sec. The peak count rate was ~700 counts/sec (15-350 keV), at ~2 sec after the trigger. Due to an observing constraint, Swift will not slew until T0+62.4 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is S. R. Oates (sro 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: 8228 SUBJECT: GRB 080915: ROTSE-III Optical Limits DATE: 08/09/15 00:45:01 GMT FROM: Wiphu Rujopakarn at U AZ/Steward W. Rujopakarn (Steward), H. Swan (U Mich), T. Guver (U Arizona) report on behalf of the ROTSE collaboration: ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 080915 (Swift trigger 324744; Oates et al., GCN 8227), producing images beginning 11.2 s after the GCN notice time. An automated response took the first image at 00:03:42.2 UT, 52.2 s after the burst, under cloudy conditions. These observations were affected by the full moon. We took 10 5-sec, and 1 20-sec exposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is on going. Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma Swift/BAT error circle. Individual images have limiting magnitudes ranging from 14.0-14.3; we set the following specific limit. start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd? -------------------------------------------------------------------- 00:03:42.2 00:03:47.2 5 14.2 52.2 N //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8230 SUBJECT: GRB 080915, Swift-BAT refined analysis DATE: 08/09/15 12:32:14 GMT FROM: Scott Barthelmy at NASA/GSFC T. Ukwatta (GWU), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), S. R. Oates (UCL-MSSL), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from recent telemetry downlinks, we report further analysis of BAT GRB 080915 (trigger #324744) (Oates, et al., GCN Circ. 8227). The BAT ground-calculated position is RA, Dec = 17.911, -76.042 deg, which is RA(J2000) = 01h 11m 38.5s Dec(J2000) = -76d 02' 29.9" with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 89%. The mask-weighted light curve shows a single FRED-like peak starting at ~T-5 sec, peaking at ~T+4 sec and ending at ~T+25 sec. T90 (15-350 keV) is 14 +- 5 sec (estimated error including systematics). The time-averaged spectrum from T-1.2 to T+16.2 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.64 +- 0.29. The fluence in the 15-150 keV band is 2.3 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+3.03 sec in the 15-150 keV band is 0.5 +- 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/324744/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8231 SUBJECT: GRB 080915: Swift-XRT afterglow detection and analysis DATE: 08/09/15 12:34:11 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) and S.R. Oates (MSSL/UCL) report on behalf of the Swift-XRT team. We have analysed 1.7 ks of XRT data on GRB080915 (Oates et al, GCN Circ 8227), beginning 4.9 ks after the GRB trigger. Swift did not slew immediately to the burst due to an Earth limb constraint. We find a faint, fading source with a mean count rate ~0.01 counts per second at a position of RA, Dec=17.9473, -76.0204 degrees, which is equivalent to: RA (J2000): 01h 11m 47.35s Dec (J2000): -76d 01' 13.4" with an uncertainy of 6.5 arcsec (radius, 90% containment). This position is 54 arcsec from the BAT position, within the BAT error circle. The light curve shows a power-law decay with an index of 0.94 (+1.19/-0.58); the large uncertainty arises because the light curve contains only 2 points. A spectrum formed from the PC data can be modelled with an absorbed power-law. The absorption column is poorly constained, but consistent with the Galactic value of 6.7 x 10^20 cm^-2 (Kalberla et al. 2005), and the photon index is 2.3 (+2.6, -1.3). If the light curve continues to decay at alpha=0.94 we predict a count rate at T0+24 hrs of 0.0018 counts per second. This corresponds to an observed (unabsorbed) 0.3-10 keV flux of 6.36 x 10^-14 (1.22 x 10^-13) erg cm^-2 s^-1. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8232 SUBJECT: GRB 080915: Swift/UVOT Upper Limits DATE: 08/09/15 13:39:55 GMT FROM: Alice Breeveld at MSSL-UCL A. Breeveld (MSSL-UCL) and S.R. Oates (MSSL-UCL) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of GRB 080915 (Oates et al., GCN Circ. 8227) with settled exposures starting 3872s after the trigger. We do not find a source in any of the UVOT observations inside the XRT error circle (Evans et al., GCN Circ. 8231). The 3-sigma upper limits in the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for detecting a source in the first white finding chart exposure and subsequent co-added exposures are: Filter T_start T_stop Exp Mag (3-sigma UL) (s) (s) (s) ========================================================= white (FC) 3872 3972 98.2 > 19.9 white 5004 5204 196.6 > 20.5 v 3979 4179 196.6 > 18.8 v 9633 10539 885.1 > 19.7 b 4799 4999 196.6 > 19.6 u 4594 4794 196.6 > 19.1 uvw1 4389 4589 196.6 > 19.3 uvm2 4184 11087 731.3 > 20.4 uvw2 5210 5329 117.3 > 19.6 The values quoted above are not corrected for the expected Galactic extinction corresponding to a reddening of E(B-V) = 0.049 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8233 SUBJECT: GRB 080915: REM NIR early observations DATE: 08/09/15 15:28:59 GMT FROM: Stefano Covino at Brera Astronomical Observatory S. Covino, P. D'Avanzo, L.A. Antonelli, D. Malesani, D. Fugazza, L. Calzoletti, S. Campana, G. Chincarini, M.L. Conciatore, S. Cutini, V. D'Elia, F. D'Alessio, F. Fiore, P. Goldoni, D. Guetta, C. Guidorzi, G.L. Israel, E. Maiorano, N. Masetti, A. Melandri, E. Meurs, L. Nicastro, E. Palazzi, E. Pian, S. Piranomonte, L. Stella, G. Stratta, G. Tagliaferri, G. Tosti, V.Testa, S.D. Vergani, F. Vitali report on behalf of the REM team: The robotic 60-cm REM telescope located at La Silla (Chile) observed automatically the field of the GRB 080915 (Oates et al. GCN 8227) on Sep 15 starting from about 2 min after the GRB time for 30 min. In the XRT error circle (Evans et al. GCN 8231) we see no sources fainter than the 2MASS limits in the J, H and K bands. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8234 SUBJECT: GRB 080915B: Swift detection of a burst DATE: 08/09/15 16:04:26 GMT FROM: David Palmer at LANL H. Ziaeepour (UCL-MSSL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), C. Gronwall (PSU), S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU), J. Mao (INAF-OAB), P. T. O'Brien (U Leicester), S. R. Oates (UCL-MSSL), J. P. Osborne (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), A. M. Parsons (GSFC), D. Perez (U Leicester), M. Perri (ASDC), T. Sakamoto (NASA/UMBC), R. L. C. Starling (U Leicester), G. Stratta (ASDC) and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team: At 15:53:35 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 080915B (trigger=324805). The BAT on-board calculated location is RA, Dec 213.078, -11.473 which is RA(J2000) = 14h 12m 19s Dec(J2000) = -11d 28' 23" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single FRED peak structure with a duration of about 5 sec. The peak count rate was ~13,000 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to the Solar observing constraint, Swift cannot slew to the BAT position until mid-December. There will thus be no XRT or UVOT data for this trigger. Burst Advocate for this burst is H. Ziaeepour (hz 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: 8236 SUBJECT: GRB 080915B, Swift-BAT refined analysis DATE: 08/09/15 19:49:30 GMT FROM: Scott Barthelmy at NASA/GSFC K. McLean (GSFC/UMD), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU), H. Ziaeepour (UCL-MSSL) (i.e. the Swift-BAT team): Using the data set from T-28 to T+930 sec from the recent telemetry downlink, we report further analysis of BAT GRB 080915B (trigger #324805) (Ziaeepour, et al., GCN Circ. 8234). The BAT ground-calculated position is RA, Dec = 213.088, -11.491 deg, which is RA(J2000) = 14h 12m 21.2s Dec(J2000) = -11d 29' 26.9" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 74%. The mask-weighted light curve shows a roughly symmetric peak starting at ~T-0.5 sec, peaking at ~T+0.6 sec, and ending at ~T+4.5 sec. T90 (15-350 keV) is 3.9 +- 0.7 sec (estimated error including systematics). The time-averaged spectrum from T-0.5 to T+6.1 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.48 +- 0.35, and Epeak of 42.3 +- 9.1 keV (chi squared 54.5 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 9.9 +- 0.6 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+0.18 sec in the 15-150 keV band is 8.5 +- 0.3 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.02 +- 0.08 (chi squared 62.6 for 57 d.o.f.). 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/324805/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8248 SUBJECT: GRB 080915a, SMARTS optical/IR observations DATE: 08/09/16 19:57:08 GMT FROM: Bethany Cobb at Yale U B. E. Cobb (UC Berkeley), reports: Using the ANDICAM instrument on the SMARTS 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 080915a (GCN 8227, Oates et al.) with a mid-exposure time of 2008-09-15 01:54 UT (~1.9 hrs post-burst). We then re-observed the field at 2008-09-16 6:12 UT (~30.2 hrs post-burst). Total summed exposure times for each observation amounted to 36 minutes in I and 30 minutes in J. A comparison of our two epochs of imaging reveals no variable source at the position of the X-ray afterglow reported by Evans et al. (GCN 8231). Our limiting magnitudes are I>21.9 and J>20.1. (Optical photometry is calibrated against Landolt standard stars and IR photometry is calibrated against 2MASS stars in the field.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 8268 SUBJECT: GRB 080915A: GROND upper limits DATE: 08/09/18 15:09:18 GMT FROM: Thomas Kruehler at MPE/MPI A. Rossi (Tautenburg Obs.), T. Kruehler, J. Greiner, A. Yoldas, C. Clemens, R. Filgas (all MPE Garching), A. Kupcu Yoldas (ESO) and G. Szokoly (Eoetvoes Univ., Budapest), report on behalf of the GROND team: GROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile), started observations of the field of GRB 080915A (Oates et al. GCN #8227) in g'r'i'z'JHK at 00:07:25 UT on 2008-09-15, 4.6 minutes after the burst and continued for 130 minutes. The observations were resumed in the following night, starting at 05:18:45 UT and continued for 70 minutes. We detect 2 sources, one inside the XRT error circle (Evans et al.GCN #8231) at coordinates RA, DEC (J2000) = 01:11:47.83, -76:01:13.7, the other at the edge of the XRT error circle at coordinates RA, DEC (J2000) = 01:11:45.4, -76:01:10.5. A comparison of the two observing runs does not reveal any evidence for variability. We conclude that most likely none of them is associated with GRB 080915A. The co-added images from the first run then yield the following upper limits measured at a mid-time of 0.038 days after the trigger and calibrated on the SDSS standard star SA95-190: g' > 23.8 r' > 23.7 i' > 23.5 z' > 23.1 J > 20.5 H > 19.3 K > 18.3