Gamma-ray Burst 050318

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  
  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 18 Mar 05 15:45:38 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     111529,   Seg_Num: 0
  GRB_RA:           49.678d {+03h 18m 43s} (J2000),
                    49.722d {+03h 18m 53s} (current),
                    49.261d {+03h 17m 03s} (1950)
  GRB_DEC:         -46.403d {-46d 24' 11"} (J2000),
                   -46.385d {-46d 23' 03"} (current),
                   -46.584d {-46d 35' 02"} (1950)
  GRB_ERROR:       4.00 [arcmin radius, statistical only]
  GRB_INTEN:       3359 [cnts]    Peak=205 [cnts/sec]
  TRIGGER_DUR:     0.512 [sec]
  TRIGGER_INDEX:   69     E_range: 15-50 keV
  BKG_INTEN:       38827 [cnts]
  BKG_TIME:        56664.00 SOD {15:44:24.00} UT
  BKG_DUR:         8 [sec]
  GRB_DATE:        13447 TJD;    77 DOY;   05/03/18
  GRB_TIME:        56677.17 SOD {15:44:37.17} UT
  GRB_PHI:         -78.86 [deg]
  GRB_THETA:        22.20 [deg]
  SOLN_STATUS:     0x3
  RATE_SIGNIF:     16.82 [sigma]
  IMAGE_SIGNIF:    9.00 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +0  +1 +10  +0  +0 -43  +1 
  SUN_POSTN:       358.30d {+23h 53m 12s}   -0.74d {-00d 44' 14"}
  SUN_DIST:         63.93 [deg]
  MOON_POSTN:       98.42d {+06h 33m 42s}  +28.27d {+28d 16' 09"}
  MOON_DIST:        86.67 [deg]
  MOON_ILLUM:      58 [%]
  GAL_COORDS:      256.48,-55.24 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:       23.53,-60.88 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Coordinates.  
  COMMENTS:        This is a rate trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  

• red DSS finding chart ps-file
  
  
• GCN/SWIFT NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Fri 18 Mar 05 15:47:13 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     111529,   Seg_Num: 0
  GRB_RA:           49.678d {+03h 18m 43s} (J2000),
                    49.722d {+03h 18m 53s} (current),
                    49.261d {+03h 17m 03s} (1950)
  GRB_DEC:         -46.403d {-46d 24' 11"} (J2000),
                   -46.385d {-46d 23' 03"} (current),
                   -46.584d {-46d 35' 02"} (1950)
  GRB_DATE:        13447 TJD;    77 DOY;   05/03/18
  GRB_TIME:        56677.17 SOD {15:44:37.17} UT
  TRIGGER_INDEX:   69
  GRB_PHI:         -78.86 [deg]
  GRB_THETA:        22.20 [deg]
  DELTA_TIME:      19.00 [sec]
  LC_URL:          sw00111529000msb.lc
  SUN_POSTN:       358.30d {+23h 53m 12s}   -0.74d {-00d 44' 14"}
  SUN_DIST:         63.93 [deg]
  MOON_POSTN:       98.42d {+06h 33m 42s}  +28.27d {+28d 16' 09"}
  MOON_DIST:        86.67 [deg]
  MOON_ILLUM:      58 [%]
  GAL_COORDS:      256.48,-55.24 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:       23.53,-60.88 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-BAT GRB Lightcurve.  
  COMMENTS:        This does not match any source in the ground catalog.  
  

  
• GCN notice #3111
  H. Krimm (GSFC/USRA), S. Barthelmy, L. Barbier (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (GSFC/UMD), C. Markwardt (GSFC/UMD), T. McMahon (Langston U.), P. Meszaros (PSU), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Still (GSFC/USRA), M. Suzuki (Saitama), M. Tripicco (GSFC-SSAI) J. Tueller (GSFC) on behalf of the Swift-BAT team:
  At 15:44:37 UT, the Swift Burst Alert Telescope (BAT) triggered and located on-board GRB 050318. The spacecraft did not automatically slew to the burst location because of an observing constraint. The orbit is such that we just started the approximate 6-hour gap in telemetry downlink orbits, so it will be ~7 hours before we get the full data set on this burst and can say anything more than what is available from the real-time TDRSS messages.
  Using the time interval of the trigger of the burst (0.5 sec), the ground-calculated location is RA,Dec 49.651,-46.392 (J2000) with an uncertainty of 3 arcmin (radius, including a systematic uncertainty, 90% containment). The burst was 22 degrees off the BAT boresight (75% coding).
  The burst lightcurve has 2 peaks. The first peak is ~3 sec long with a peak count rate of 4000 cnts/sec. The second peak starts at T+25 and lasts ~15 sec with a peak rate of 4500 cnts/sec (15-350 keV) .
• GCN notice #3112
  C. B. Markwardt (GSFC/UMD), P. Boyd (GSFC/UMBC), N. Gehrels (GSFC) K. Hurley (UCB), F. E. Marshall (GSFC), M. Still (GSFC/USRA)
  RXTE observed GRB 050318 starting at 17:47 UTC (123 minutes after the BAT trigger), at the BAT reported position (Krimm et al, GCN Circ #3111). The exposure was 768 seconds. The RXTE PCA is a non-imaging instrument with a field of view of approximately 1 degree (FWHM).
  A PCA flux of 7E-12 erg/s/cm^2 was detected (2-10 keV), which is about four times the expected fluctuations due to the cosmic X-ray background. The flux is primarily below 6 keV. No obvious temporal variations are detected.
• GCN notice #3113
  J. A. Nousek, D. C. Morris, D. N. Burrows, D. Grupe, M. Chester, P. Meszaros (PSU), V. La Parola, V. Mangano (INAF-IASF/Palermo), S. Campana, G. Tagliaferri (INAF-OAB), M. Capalbi (ASDC), O. Godet, M. R. Goad (U. Leicester), L. Cominsky (Sonoma State U.), J. Greiner (MPE), H. Krimm, M. Still, and N. Gehrels (GSFC), report on behalf of the Swift XRT team:
  The Swift BAT instrument detected GRB 050318 at 15:44:37 UT on 18 March 2005 (Krimm et al 2005, GCN 3111). The BAT position was within the Swift Earth horizon constraint. The observatory executed an automated slew to the BAT position and the XRT began taking data in Auto State at 16:39:14 UT. Swift did not have contact with the ground station until about 22:29 UT. On receiving the data at Penn State, a preliminary analysis was performed by the XRT team. We find a bright uncataloged, rapidly fading X-ray source located at:

  RA(J2000) = 03:18:50.8,
  Dec(J2000) = -46:23:45.1.
  

  We estimate an uncertainty of about 6 arcseconds. This source is 87 arcseconds from the BAT position reported in GCN 3111.
• GCN notice #3114
  John Mulchaey and Edo Berger (Carnegie Observatories) report:
  "On 2005, March 18.995 UT we imaged the BAT error circle of GRB 050318 (GCN 3111) with IMACS on the Magellan/Baade telescope in the R-band. Within the 6" radius XRT error circle (GCN 3113) we find a single bright object which is not present in the DSS at coordinates (J2000):

          RA  =  03:18:51.0
          DEC = -46:23:44
  

  with an uncertainty of about 0.5" in each coordinate. We consider this object to be the optical afterglow of GRB 050318."
• GCN notice #3115
  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. Rosen, S. Koch (PSU), M. Carter, H. Huckle (MSSL), P. Broos (PSU), T. Kennedy, P. Smith, B. Hancock (MSSL), H. Krimm (GSFC/USRA), J. Nousek (PSU), N. Gehrels (GSFC), on behalf of the Swift UVOT team.
  The Swift Ultra-Violet/Optical Telescope (UVOT) began settled observations of the field of GRB 050318 (Krimm et al; GCN 3111) at 16:39:16 UT, 3,279s after the BAT trigger. The delay in acquiring the target was caused by an earth limb constraint. The first data taken after spacecraft settling was a 100s V image, sent directly to the ground through the TDRSS system, with pixel binning of 8x8 to reduce telemetry. Binned pixel sizes are 4x4 arcsec and the field of view is 5.3x5.3 arcmin. Mid-exposure time was 3,329s after the trigger. A comparison against the Digitized Sky Survey reveals a new source inside the BAT and XRT (Nousek et al; GCN 3113) error circles at:
  RA = 03 18 51.2(1) Dec = -46 23 43(2) J2000
  and consistent with the R-band detection of Mulchaey & Berger (GCN 3114) The V band magnitude is V = 18.4(3). The magnitude is based on ground data and will require confirmation by flight calibration.
  The full-resolution version of this image will be transmitted to the ground during the next Malindi pass providing an improved position.
• GCN notice #3122
  Edo Berger and John Mulchaey (Carnegie Observatories) report:
  "Using IMACS on the Magellan/Baade telescope we also obtained spectra of the afterglow of GRB 050318 (GCN 3114) on 2005, March 19 UT. We find several absorption features corresponding to two redshift systems at z=1.20 and z=1.44. We conclude that the redshift of GRB 050318 is z=1.44."
• GCN notice #3123
  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 (PSU), S. Rosen, K. McGowan (MSSL), S. Koch (PSU), M. Carter, H. Huckle (MSSL), P. Broos (PSU), T. Kennedy, P. Smith, B. Hancock (MSSL), H. Krimm (GSFC/USRA), J. Nousek (PSU), N. Gehrels (GSFC), on behalf of the Swift UVOT team.
  Analysis of a more complete data set from the Swift-UVOT of GRB 050318 (Krimm, et al., GCN 3111) yields an improved position from stacked V image exposures of
  RA = 03h 18m 51.15(2)s, Dec = -46d 23m 43.7(3)s (J2000).
  Images in various filters, stacked over the first 34 ksec after the trigger indicate time-averaged instrumental magnitudes of UVW2 > 22.0, UVM2 > 22.1, UVW1 > 21.5, U = 20.5(2), B = 20.0(1) and V = 19.7(1). This indicates either a highly reddened source, or an object of redshift z ~ 2.7 in front of the burst.
  Magnitudes are based on ground calibration and will require confirmation in flight.
• GCN notice #3133
  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).
• GCN notice #3134
  H. Krimm (GSFC/USRA), S. Barthelmy, L. Barbier (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (GSFC/UMD), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Still (GSFC/USRA), M. Suzuki (Saitama), J. Tueller (GSFC) on behalf of the Swift-BAT team:
  Continued analysis of the available data for the Swift-BAT GRB 050318 (Krimm, et al., GCN 3111) yields the following additional results. Due to an error in an on-board data processing script, event data from times after T+31.4 seconds were not recorded. Based on analysis of the rate data, we estimate that the lost event data represent about 18 per cent of the total burst flux. The fluence derived from the available event data and scaled to cover the entire burst is 2.1 X 10^-6 erg/cm^2 in the 15-350 keV band. The 1-s peak flux is 3.8 ph/cm^2/s (also 15-350 keV). The photon index of the 1-s peak spectrum (T+28.5 s) is 1.9 +/- 0.12 (90% confidence). The time averaged spectrum yields a photon index of 2.1 +/- 0.11 (90% confidence). The overall measure of burst duration is T90 = 32 +/- 2 s (including systematics).