Gamma-ray Burst 050509

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 09 May 05 01:46:45 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     118707,   Seg_Num: 0
GRB_RA:          310.588d {+20h 42m 21s} (J2000),
                 310.626d {+20h 42m 30s} (current),
                 310.239d {+20h 40m 57s} (1950)
GRB_DEC:         +54.070d {+54d 04' 12"} (J2000),
                 +54.089d {+54d 05' 22"} (current),
                 +53.890d {+53d 53' 22"} (1950)
GRB_ERROR:       4.00 [arcmin radius, statistical only]
GRB_INTEN:       6255 [cnts]    Peak=319 [cnts/sec]
TRIGGER_DUR:     1.024 [sec]
TRIGGER_INDEX:   137     E_range: 15-50 keV
BKG_INTEN:       37350 [cnts]
BKG_TIME:        6376.00 SOD {01:46:16.00} UT
BKG_DUR:         8 [sec]
GRB_DATE:        13499 TJD;   129 DOY;   05/05/09
GRB_TIME:        6388.51 SOD {01:46:28.51} UT
GRB_PHI:          85.85 [deg]
GRB_THETA:         8.15 [deg]
SOLN_STATUS:     0x3
RATE_SIGNIF:     19.94 [sigma]
IMAGE_SIGNIF:    9.00 [sigma]
MERIT_PARAMS:     +1  +0  +0  +0  +1  +6  +0  +1 -18  +1 
SUN_POSTN:        46.09d {+03h 04m 22s}  +17.35d {+17d 20' 45"}
SUN_DIST:         79.16 [deg]
MOON_POSTN:       53.85d {+03h 35m 23s}  +22.42d {+22d 24' 60"}
MOON_DIST:        79.35 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:       91.36,  7.25 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      347.20, 66.95 [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:     Mon 09 May 05 01:47:29 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     118707,   Seg_Num: 0
POINT_RA:        310.615d {+20h 42m 28s} (J2000)
POINT_DEC:       +54.073d {+54d 04' 22"} (J2000)
GRB_DATE:        13499 TJD;   129 DOY;   05/05/09
GRB_TIME:        6442.76 SOD {01:47:22.76} UT
COUNTS:          2    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.  
COMMENTS:        No source found in the image.

GCN/SWIFT NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 09 May 05 01:49:04 UT
NOTICE_TYPE:     Swift-XRT Lightcurve
TRIGGER_NUM:     118707,   Seg_Num: 0
POINT_RA:        310.620d {+20h 42m 29s} (J2000)
POINT_DEC:       +54.074d {+54d 04' 25"} (J2000)
LC_START_DATE:   13499 TJD;   129 DOY;   05/05/09
LC_START_TIME:   6445.49 SOD {01:47:25.49} UT
LC_STOP_DATE:    13499 TJD;   129 DOY;   05/05/09
LC_STOP_TIME:    6528.44 SOD {01:48:48.44} UT
LC_LIVE_TIME:    49.86 [sec], 60.1%
DELTA_TIME:      86317.05 [sec]
N_BINS:          34
TERM_COND:       2
LC_URL:          sw00118707000msx.lc
SUN_POSTN:        46.09d {+03h 04m 22s}  +17.35d {+17d 20' 45"}
SUN_DIST:         79.14 [deg]
MOON_POSTN:       53.86d {+03h 35m 26s}  +22.42d {+22d 25' 09"}
MOON_DIST:        79.33 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:       91.37,  7.24 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      347.24, 66.94 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-XRT Lightcurve.  
COMMENTS:        This Lightcurve was terminated by the 'Snapshot End' condition.

GCN/SWIFT NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Mon 09 May 05 01:49:51 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     118707,   Seg_Num: 0
GRB_RA:          310.588d {+20h 42m 21s} (J2000),
                 310.626d {+20h 42m 30s} (current),
                 310.239d {+20h 40m 57s} (1950)
GRB_DEC:         +54.070d {+54d 04' 12"} (J2000),
                 +54.089d {+54d 05' 22"} (current),
                 +53.890d {+53d 53' 22"} (1950)
GRB_DATE:        13499 TJD;   129 DOY;   05/05/09
GRB_TIME:        6388.51 SOD {01:46:28.51} UT
TRIGGER_INDEX:   137
GRB_PHI:          85.85 [deg]
GRB_THETA:         8.15 [deg]
DELTA_TIME:      76.00 [sec]
LC_URL:          sw00118707000msb.lc
SUN_POSTN:        46.09d {+03h 04m 22s}  +17.35d {+17d 20' 45"}
SUN_DIST:         79.16 [deg]
MOON_POSTN:       53.85d {+03h 35m 23s}  +22.42d {+22d 24' 60"}
MOON_DIST:        79.35 [deg]
MOON_ILLUM:      1 [%]
GAL_COORDS:       91.36,  7.25 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:      347.20, 66.95 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
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:           
COMMENTS:        The next comments were copied from the BAT_POS Notice:  
COMMENTS:        This is a GRB.

GCN notice #3379
C. Hurkett, E. Rol, (U Leicester), L. Barbier (GSFC), S. Barthelmy (GSFC), A. Blustin (MSSL), D. Burrows (PSU), J. Cummings (GSFC/NRC), N. Gehrels (GSFC), J. Kennea (PSU), C. Markwardt (GSFC/UMD), on behalf of the Swift Team;
At 01:46:28 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB050509 (trigger=118707). The BAT on-board calculated location is RA, Dec 310.588, +54.070 (J2000) with an uncertainty of 3 arcmin (radius, 3-sigma, including estimated systematic uncertainty). The BAT light curve shows a single main peak with a small peak on the rising edge (at T-6sec). The total duration is ~13 sec. The BAT peak count rate is ~2300 events/sec at T_zero (15-350 keV).
The Swift spacecraft slewed promptly onto the BAT position. The XRT imaged the field at 01:47:22.76 (54.8s after the burst), but did not find any bright source in the field. An XRT position will be determined by analysis of the full data following the next ground station pass.
The Swift Ultra Violet/Optical (UVOT) observations began at 01:47:20.5 UT, 52 seconds after the BAT trigger. The first data taken after the spacecraft settled was a 90 sec exposure using the V filter with the midpoint of the observation at 97 sec after the BAT trigger. Based on a preliminary comparison with the DSS and USNO-B, we detect no new source within the BAT error circle down to an approximate five sigma limiting magnitude of 17.3.
The observation was truncated by an observing constraint at 01:50:00 UT after approximately 110 sec.
GCN notice #3380
J. A. Kennea, D. N. Burrows (PSU), C. P. Hurkett, E. Rol (U. Leicester) and N. Gehrels (NASA/GSFC) report on behalf of the Swift XRT team:
The Swift BAT instrument detected GRB 050509a at 01:46:28 UT on 9th May 2005 (GCN Circ 3379). The observatory executed an automated slew to the BAT position and the XRT began taking data at 01:47:22 UT. The XRT was in Auto state but was not able to centroid on the afterglow due to low source intensity. From downlinked data we find a uncatalogued X-ray source located at:
```
RA(J2000) = 20:42:19.7,
Dec(J2000) = +54:04:16.2
```
We estimate an uncertainty of about 6 arcseconds radius (90% containment). This position is 13 arcseconds from the BAT position reported in GCN 3379.
GCN notice #3382
E.S. Rykoff (U Mich), H. Swan (U Mich), B. Schaefer (Louisiana State), R. Quimby (U Texas), report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 050509A (Swift trigger 118749), producing images beginning 10.0 s after the GCN notice time. An automated response took the first image at 04:00:43.0 UT, 23.7 s after the burst, under excellent conditions. We took 10 5-sec, 10 20-sec and 60+ 60-sec eposures. These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging is ongoing.
Comparison to the DSS (second epoch) reveals no new sources within the 3-sigma error circle, nor do we detect the tentative UVOT source (Hurkett et al, GCN 3381). Individual images have limiting magnitudes ranging from 17.07-18.48. In particular, we set a limit of magnitude 17.25 in a single 5 s exposure, starting 23.7 s after the burst. Coadding the images into sets of 10 reveals no new sources down to limits of 18.63 (77 s effective length (t_end - t_start), beginning 23.7s post-burst), 18.72 (298.5s effective length, beginning 100.6s post-burst), and 19.46 (695.6s effective length, beginning 399.1s post-burst).
GCN notice #3389
GRB 050509A: Optical observations
J. P. U. Fynbo, B. L. Jensen, J. Hjorth, P. Jakobsson,=20 J. M. Castro Cer=F3n, H. Pedersen, D. Watson (Niels Bohr Institute), J. N=E4r=E4nen (Nordic Optical Telescope) report:
"Using ALFOSC on the 2.56m Nordic Optical Telescope we have obtained=20 I-band imaging of the XRT error circle for GRB 050509A (Swift trigger 118707, GCN 3379, 3380) at two epochs starting ~20 min and ~2.5 hr after the GRB trigger. In the XRT error-circle we detect several sources. One source is less than 2" from the centre of the XRT error=20 circle and not seen in the DSS-II (red). The position of this source is:
```
RA(2000) = 20:42:19.60,  Dec(2000) = +54:04:17.8
```
The source is fainter than the sensitivity of the DSS-II red image and=20 has an estimated magnitude of I =3D 21.7 (not corrected for a galactic=20 extinction of A_I =3D 1.15 mag). The source does not vary significantly=20 between the two epochs. An image of the field is shown at:
http://www.astro.ku.dk/~brian_j/grb/grb050509A/ "
GCN notice #3394
T. Poole (MSSL), C. Hurkett (Leicester), S. Hunsberger (PSU), A. Breeveld (MSSL), P. Boyd (GSFC), N. Gehrels (GSFC), K. Mason (MSSL), J. Nousek (PSU), on behalf of the Swift UVOT team
The Swift Ultra-Violet/Optical Telescope (UVOT) began observations of GRB050509a on May 09, 2005 at 01:47:20.5 UT, 52 seconds after the initial Swift BAT trigger (Hurkett et al., GCN 3379). The XRT error circle (Kennea et al., GCN 3380) falls partially on a known source from the DSS. We detect no new sources at the Swift XRT position (Kennea et al, GCN 3380). The limiting magnitudes (in 6" radius apertures) in each of the UVOT filters are as follows:
```
Filter    Lim_Mag      Lim_mag  Total duration  T_start T_mid
            5sigma       3sigma  (s)             (s)     (s)

V          18.23        18.79   191             52      1853
UVW1       18.97        19.52   210             5722    5827
UVM2       20.29        20.84   921             3763    4739
```
UVOT only observed GRB050509b in V, UVW1 and UVM2 because it's run of observations were interrupted by GRB050509b.
The magnitudes are based on preliminary zero-points, measured in orbit, and will require refinement with further calibration.
This message may be cited.
GCN notice #3407
L. Barbier (GSFC), S. Barthelmy (GSFC), P. Boyd (GSFC-UMBC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), T. Mitani (ISAS) D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Suzuki (Saitama), J. Tueller (GSFC), W. Voges (MPE)
on behalf of the Swift/BAT team:
At 01:46:28 UT Swift-BAT detected GRB 050509a (trigger=118707) (GCN Circ 3379, C. Hurkett, et al.). The refined BAT ground position is (RA,Dec) = 310.608,+54.059, [deg; J2000] {20:42:24; +54:00:14} +- 0.45 arcmin, (95% containment). XRT found an uncatalogued x-ray source 13 arcseconds from the BAT position (GCN Circ 3380, J. Kennea, et al.) The coding was 100% in the FOV.
The 1-s maskweighted lightcurve shows two distinct peaks. T90 (15-350 keV) is (11.6 +- 1.0) seconds (estimated error including systematics).
The photon index of the time-averaged spectrum is 2.1 +- 0.2. The fluence in the 15-350 keV band is (4.6 +- 0.7) x 10^-7 erg/cm2. The 1-s peak photon flux measured from T0+0.388 second in the 15-350 keV band is (0.98 +- 0.13) ph/cm2/s. All the quoted errors are at the 90% confidence level.
GCN notice #3460
GRB 050509.074: Further I-band imaging
Johan P. U. Fynbo, Brian L. Jensen, Jens Hjorth, Pall Jakobsson, J. M. Castro Cer=F3n, H. Pedersen, Darach Watson (Niels Bohr Institute), Tapio Pursimo, Raine Karjalainen, John Telting (Nordic Optical Telescope), Bj=F6rn Voss (University of Kiel) report:
"Using StanCAM on the 2.56m Nordic Optical Telescope we have obtained further I-band imaging of the XRT error circle for GRB 050509.074 (Swift trigger 118707, GCN 3379, 3380) on May 19.17. All sources detected in our early I-band images from 20 min and 2.5 hr after the burst (GCN 3389) are also detected in the image from May 19. Our 3-sigma upper limit on the magnitude of any transient source in the XRT error circle (except in the eastern part covered by the bright star) is I=3D22.5. Images of the field are shown at:
http://www.astro.ku.dk/~brian_j/grb/grb050509.074/ "

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Jochen Greiner, last update: 23-May-2005 [Disclaimer]