//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3094 SUBJECT: Swift-BAT detection of GRB 050315 DATE: 05/03/15 21:55:41 GMT FROM: Ann M. Parsons at NASA/GSFC/Swift A. Parsons, S. Barthelmy, L. Barbier (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), R. Fink, N. Gehrels (GSFC), S. Holland (GSFC/USRA), D. Hullinger (GSFC/UMD), K. Hurley (UCB), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), S. Piranomonte (ASDC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), A. Smale (NASA HQ), M. Suzuki (Saitama), J. Tueller (GSFC) on behalf of the Swift-BAT team: At 20:59:42 UT, the Swift Burst Alert Telescope (BAT) triggered and located on-board GRB 050315. The spacecraft automatically slewed to the burst location, and UVOT began automated observations. XRT was not in a mode suitable for immediate position determination. Using the time interval of the trigger of the burst, the ground-calculated location is RA,Dec 306.476,-42.591 (J2000) with an uncertainty of 3 arcmin (radius, including a systematic uncertainty, 90% containment). The burst was 40 degrees off the BAT boresight (60% coding). The burst lightcurve has 2 overlapping FRED-like peaks. The duration is ~40 sec. There is no further emmission out to T+180 sec, where the end of the real-time TDRSS data ends. The peak count rate is ~2500 counts/sec. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3095 SUBJECT: GRB 050315: Early Observations with Swift/UVOT DATE: 05/03/15 23:42:15 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. Rosen, K. McGowan, M. De Pasquale (MSSL), P. Boyd (GSFC/UMBC), S. T. Holland, M. Still (GSFC/USRA), W. Landsman (GSFC), S. Hunsberger (PSU), A. Breeveld (MSSL), P. Roming (PSU), K. Mason, P. Schady (MSSL), M. Ivanushkina (PSU), T. Poole (MSSL), C. Gronwall (PSU), A. Blustin (MSSL), P. Brown, S. Koch (PSU), M. Carter, H. Huckle (MSSL), P. Broos (PSU), T. Kennedy, P. Smith, B. Hancock (MSSL), A. Parsons (GSFC), J. Nousek (PSU), N. Gehrels (GSFC), on behalf of the Swift UVOT team. The Swift Ultra-Violet/Optical Telescope (UVOT) began observing the field of GRB 050315 (GCN 3094) at 21:01:13 UT, approximately 90 seconds after the BAT trigger. The first image was sent down via the TDRSS link approximately 200 seconds after the trigger. This image was a 100 second exposure taken with the V filter. It was centred on the BAT position, and had a size of 5 x 5 arcminutes, which covered 88% of the BAT error circle. The middle of the exposure was 140.19 seconds after the BAT trigger. The image was binned 8 x 8 to reduce the bandwidth required for transmission. A comparison against the DSS showed no new sources down to a 5-sigma limiting magnitude of approximately V = 18.5. We stress that this limiting magnitude is based on ground calibrations and may be uncertain by approximately 0.5 mag. The full-resolution version of this image will be transmitted to the ground during the next Malindi pass, which will occur at approximately 0000 UTC March 16, 2005. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3097 SUBJECT: GRB 050315: Swift XRT Position DATE: 05/03/16 01:06:00 GMT FROM: David Burrows at PSU/Swift D. C. Morris, D. N. Burrows, J. E. Hill, J. A. Kennea, J. A. Nousek (PSU), C. Pagani, G. Chincarini (INAF-OAB), A. F. Abbey, P. T. O'Brien (U. Leicester), G. Cusumano, T. Mineo (INAF-IASF/Palermo), M. Capalbi (ASDC), A. Parsons, S. Holland, N. White, N. Gehrels (GSFC), K. Mason (MSSL), and K. Hurley (UCB) report on behalf of the Swift XRT team: The Swift BAT instrument detected GRB 050315 at 20:59:42 UT on 15 March 2005 (Parsons et al 2005, GCN 3094). The observatory executed an automated slew to the BAT position and the XRT began taking data at 21:01:05.5 UT. The XRT was in Manual state and made observations in Photon Counting mode. Data were dumped to the ground at about 00:00 UT on 16 March 2005 and a preliminary analysis was performed by the XRT team. We find a bright uncataloged, rapidly fading X-ray source located at: RA(J2000) = 20:25:54, Dec(J2000) = -42:36:0.2 We estimate an uncertainty of about 6 arcseconds. This source is 32 arcseconds from the BAT position reported in GCN 3094. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3098 SUBJECT: Non-detection of GRB050315 in ATCA Radio Observations DATE: 05/03/16 03:02:01 GMT FROM: Brian Schmidt at RSAA, ANU (MSSSO) Mark H Wieringa (Australia Telescope National Facility), Brian P Schmidt (Australian National University) and Alicia Soderberg (CalTech) report on behalf of a larger collaboration: "We observed a region covering the Swift burst GRB 050315 (GCN#3094) using the Australia Telescope Compact Array for 1 hour centered on March 16.02 UT. At frequencies of 4.8 and 8.6 GHz no emission was detected within the 6 arcsec diameter error circle of the XRT position (GCN#3097). The 3-sigma detection limits are 0.6 and 0.8 mJy at 4.8 and 8.6 GHz respectively. No detections above these limits are present in a larger area (1 arcmin diameter) around the XRT position." We thank the ATNF Director for making this rapid response possible. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3099 SUBJECT: GRB050315: Swift-BAT Refined analysis DATE: 05/03/16 05:10:29 GMT FROM: Takanori Sakamoto at NASA/GSFC T. Sakamoto (GSFC/NRC), S. Barthelmy, L. Barbier (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), R. Fink, N. Gehrels (GSFC), S. Holland (GSFC/USRA), D. Hullinger (GSFC/UMD), K. Hurley (UCB), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), S. Piranomonte (ASDC), G. Sato (ISAS), A. Smale (NASA HQ), M. Suzuki (Saitama), J. Tueller (GSFC) on behalf of the Swift-BAT team: Analysis of the available data for the Swift-BAT GRB050315 (Parsons et al., GCN Circ 3094) yields a fluence of > 2.8x10^-6 erg/cm2 in the 15-350 keV band and a peak flux of 2.5 ph/cm2/sec (also 15-350 keV). The photon index of the 1-s peak spectrum (T0+25 sec.) is 2.5 +- 0.3 (90% confidence). Although there is a data gap, the time averaged spectrum also shows a soft spectrum. This appears to be a soft X-ray-rich GRB. We are planning a further circular when more complete data are avaliable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3100 SUBJECT: GRB 050315: Optical afterglow identification DATE: 05/03/16 09:41:52 GMT FROM: Edo Berger at Carnegie Obs Dan Kelson and Edo Berger (Carnegie Observatories) report: "On 2005, March 16.347 UT we imaged the XRT error circle of GRB 050315 (GCN 3097) with the newly-comissioned LDSS3 instrument on Magellan/Clay in the r-band filter. Within the 6" radius error circle we find a single bright object which is not present in the DSS at coordinates (J2000): RA = 20:25:54.1 DEC = -42:36:02.2 with an uncertainty of about 0.5" in each coordinate. We consider this object to be the optical afterglow of GRB 050315." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3101 SUBJECT: GRB 050315: Absorption redshift DATE: 05/03/16 09:57:54 GMT FROM: Edo Berger at Carnegie Obs Dan Kelson and Edo Berger (Carnegie Observatories) report: "Using LDSS3 on Magellan we also obtained a 20-minute spectrum of the afterglow candidate (GCN 3100). We find several absorption features which we identify as AlIII (1854.7 and 1862.8) and SiII (1808.0) at a redshift of z=1.949. We conclude that this is the redshift of GRB 050315. Given a fluence of >2.8e-6 erg/cm^2 (GCN 3099), the isotropic-equivalent gamma-ray energy is > 2.6e52 erg." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3102 SUBJECT: GRB050315: Radio afterglow DATE: 05/03/16 18:04:36 GMT FROM: Alicia Soderberg at Caltech A. M. Soderberg (Caltech) and D. A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB collaboration: "Using the Very Large Array at 8.5 GHz, we observed the field of GRB050315 (GCN 3094) on 2005 Mar 16.68 UT (t=0.80 d). Within the XRT localization (GCN 3097), we detect a radio source at the following coordinates: RA: 20:25:54.17 Dec: -42:36:01.0 (J2000) with a positional uncertainty of ~0.5 arcsec. Noting that this source is roughly coincident with the optical afterglow position reported by Kelson and Berger (GCN 3100), we interpret this as the radio afterglow of GRB050315. Further observations are planned." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3103 SUBJECT: GRB 050315 I-band observations DATE: 05/03/16 21:51:06 GMT FROM: David Bersier at STScI D. Bersier, J. Rhoads, A. Fruchter (STScI), D. Gilbank (Toronto) report on behalf of the NOAO GRB collaboration: We have observed the field of GRB 050315 (GCN 3094) with the MOSAIC II wide-field camera on the CTIO 4m Blanco telescope, starting 0.47d after the burst. The afterglow seen in the optical and radio (GCNs 3100, 3101 and 3102) is well detected in our I-band data, taken at a mean time of 0.484d after the burst. A preliminary reduction, using an average zero point for this camera, yields mI=20.7. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3104 SUBJECT: GRB 050315, SMARTS optical/IR afterglow observations DATE: 05/03/16 22:18:02 GMT FROM: Bethany Cobb at Yale U B. E. Cobb and C. D. Bailyn (Yale), part of the larger SMARTS consortium, report: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 050315 (GCN 3094, Parsons et al.) beginning ~11.6 hours post-burst (2005-03-16 08:35:09 UT). Total summed exposure times amounted to 180s in BRIYJK and 120s in H and V. An optical source is detected in R and I at the coordinates of the reported optical afterglow candidate (GCN 3100, Kelson & Berger). This source is, however, only slightly brighter than our detection limits. Preliminary comparison with Landolt Standard PG 1047+003 and USNO B1.0 stars yields the following approximate afterglow magnitudes: R = 20.9 I = 20.3 No source was detected in B or V with upper limits of B > 22.3 and V > 21.4. Additionally, the afterglow candidate is not detected in the IR images to the following detection limits (obtained by comparison with 2MASS): J > 18.0 H > 17.4 K > 16.3 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3105 SUBJECT: GRB 050315: Swift-BAT further refined analysis DATE: 05/03/16 22:41:45 GMT FROM: Hans Krimm at NASA-GSFC H. Krimm (GSFC/USRA), S. Barthelmy, L. Barbier (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), R. Fink, N. Gehrels (GSFC), S.T. Holland (GSFC/USRA), D. Hullinger (GSFC/UMD), K. Hurley (UCB), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), S. Piranomonte (ASDC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), A. Smale (NASA HQ), M. Suzuki (Saitama), J. Tueller (GSFC) on behalf of the Swift-BAT team: Continued analysis of the full data set (now with telemetry gaps filled in) for the Swift-BAT GRB050315 (Parsons et al., GCN Circ 3094, Sakamoto et al., GCN Circ 3099) yields a fluence of 4.2 x 10^-6 erg/cm2 in the 15-350 keV band and a peak flux of 2.4 ph/cm2/sec (also 15-350 keV). The photon index of the 1-s peak spectrum (T0+24.6 sec.) is 2.4 +- 0.3 (90% confidence). The time averaged spectrum also shows a soft spectrum with a power law index of 2.3 +- 0.1 (90% confidence). The Swift mission is still in its early orbit phase and the BAT spectral response continues to be refined. Further spectral analysis is in progress. In particular, since there is an uncertainty in the energy response at the lowest energies at the current time, it is not possible to conclude that this event is an X-ray flash. The burst shows considerable structure in its light curve. There is a precursor starting ~60 seconds before the trigger and continuing up until the main peak emission begins. The first of the two main peaks has a slow rise of about ten seconds and a gradual decline interrupted at TO ~22 seconds by a second peak with a much steeper rise. The burst shows signs of spectral evolution (hard to soft) from the precursor through the two main peaks. There is no significant emission after the decay of the second peak. The overall measures of burst duration give T90 = 96 +- 10 seconds and T50 = 25 +- 5 seconds. The errors in duration are estimated systematic errors. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3110 SUBJECT: GRB 050315, SMARTS optical afterglow decay DATE: 05/03/17 21:04:47 GMT FROM: Bethany Cobb at Yale U B. E. Cobb and C. D. Bailyn (Yale), part of the larger SMARTS consortium, report: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained additional optical/IR imaging of the reported optical afterglow candidate (GCN 3100, Kelson & Berger) of GRB 050315 (GCN 3094, Parsons et al.) beginning ~35.6 hours post-burst. Total summed exposure times amounted to 10 minutes R and I and 12.5 minutes in J. The source identified as the afterglow candidate has dimmed since our previous observations (GCN 3104, Cobb & Bailyn). Preliminary comparison with Landolt Standards PG 1047+003 and RU 149 yields the following approximate afterglow magnitudes: R = 21.6 I = 21.5 The counterpart was again not detected in the IR, with a magnitude limit of J > 18.6. Our R and I observations are summarized below: time post-burst: R magnitude: I magnitude: 11.6 hours 20.9 20.3 35.6 hours 21.6 21.5 We note that the I-band observations are close to the detection limit, and have measurement errors of >0.2 magnitudes, so the evidence for a color change should be treated with caution. The R-band magnitudes have errors of ~0.2, so assuming a power-law afterglow decay (afterglow flux proportional to t^alpha), then this corresponds to an alpha of -0.57 +\- 0.25. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3128 SUBJECT: GRB 050315: Variability Analysis of Swift BAT Time History DATE: 05/03/20 23:58:18 GMT FROM: Don Lamb at U.Chicago GRB 050315: Variability Analysis of Swift BAT Time History T. Q. Donaghy, T. Sakamoto, D. Q. Lamb, E. E. Fenimore, D. E. Reichart, on behalf of the Swift BAT Team report: We have calculated the variability measure V (Fenimore and Ramirez-Ruiz 2000; Reichart et al. 2001) for GRB 050315 (Parsons et al., GCN Circular 3094), using the Swift BAT time history data for this burst. We find values V = 0.017 +/- 0.027, 0.068 +/- 0.022, 0.086 +/- 0.041, and 0.064 +/- 0.016 (68 percent confidence regions) in the 15-25 keV, 25-50 keV, 50-100 keV, and 25-100 keV energy bands, respectively. These values of V are the same within the statistical uncertainties; this is consistent with the results of Reichart et al. (2001), who found no significant trend of V with energy for BATSE bursts. Analyzing the Swift BAT spectral data for GRB 050315, we find a peak photon energy flux in 1 s of (9.2 +/- 0.6) x 10-8 erg cm-2 s-1 (68% confidence region) in the 33.9 - 339.1 keV energy band [which corresponds to the 100-1000 keV energy band in the rest frame of the source for a redshift of z = 1.949 (Kelson and Berger, GCN Circular 3101)]. This peak photon energy flux corresponds to an isotropic- equivalent peak luminosity in the 100-1000 keV energy band in the rest frame of the source of L_obs = (3.2 +/- 0.2) x 10^51 erg s-1. Using V in the 25-100 keV energy band as a luminosity (and therefore a redshift) estimator, we estimate an isotropic-equivalent luminosity in 100-1000 keV in the rest frame of the source of log L_V (erg s-1) = 51.46 +/- 0.747 and a redshift z_V = 1.94 (+2.02/-0.97) for the burst. These values are consistent with the observed values log L_obs (erg s-1) = 51.51 (+0.02/-0.04) (90% confidence region) and z = 1.949 (Kelson and Berger, GCN Circular 3101). These results are encouraging. They suggest that analyses of the Swift BAT time history data for a large sample of bursts will provide a decisive test of the validity of the variability measure V as a luminosity (and therefore a redshift) estimator, and if the analyses confirm its validity, they will make possible a better calibration of the estimator. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3133 SUBJECT: Refined Swift XRT positions for GRB050315, GRB050318 and GRB 050319 DATE: 05/03/21 22:15:51 GMT FROM: David Burrows at PSU/Swift A. P. Beardmore, K. L. Page (U. Leicester), V. Mangano (INAF-IASF/Palermo), P. Romano (INAF-OAB), M. R. Goad, O. Godet, J. P. Osborne (U. Leicester), G. Chincarini, S. Campana (INAF-OAB), D. N. Burrows, J. L. Racusin (PSU), G. Cusumano, T. Mineo (INAF-IASF/Palermo), M. Perri, F. Tamburelli (ASDC), L. Angelini, F. Marshall, N. Gehrels (GSFC) report on behalf of the Swift XRT team: We report refined XRT source positions for GRB 050315 (GCN3094, GCN3097), GRB 050318 (GCN3111, GCN3113), and GRB 050319 (GCN3117), based on improved ground-based analysis of extended data sets from these three bursts. We find the following afterglow positions: GRB 050315: RA(J2000) = 20:25:53.9, Dec(J2000) = -42:36:01.4 (P. Romano), which is 2.3" from the optical counterpart (GCN3100). GRB 050318: RA(J2000) = 03:18:51.1, Dec(J2000) = -46:23:44.7 (V. Mangano), which is 1.1" from the optical counterpart (GCN3123). GRB 050319: RA(J2000) = 10:16:48.1, Dec(J2000) = +43:32:52.3 (K. Page), which is 3.1" from the optical counterpart (GCN3116). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3294 SUBJECT: GRB 050315: potential host galaxy DATE: 05/04/19 13:53:07 GMT FROM: Javier Gorosabel at LAEFF-INTA, Madrid J. Gorosabel (IAA-CSIC, Granada), P. Laursen, B.L. Jensen, J.P.U. Fynbo, J. Hjorth, D. Watson, H. Pedersen, P. Jakobsson, J.M. Castro Cer¢n (NBI, Copenhagen), M.I. Andersen (AIP, Potsdam), report: "We have obtained deep R-band imaging of the field of the GRB 050315 optical afterglow (GCN Circ. 3100) with the 1.54m Danish telescope on La Silla. The observations were carried out during five nights (8, 9, 11, 12 & 14 April 2005) with a total exposure time of ~7 hours. In the stacked image, which has a 3 sigma limiting magnitude of 24.2, an object is detected within an arcsec of the afterglow position. This object, which we tentatively identify as the GRB 050315 host galaxy, shows an elongated shape in the E-W direction. The magnitude of the potential host galaxy is R=23.9+/-0.2. The photometric calibration is based on observations of Landolt fields. A finding chart can be found at: http://www.dsri.dk/~jgu/grb050315/FCs/GRB050315.R.Danish.medianw.gif Further sub-arsecond deep observations are necessary to clarify the nature of this object." This message can be cited.