Gamma-ray Burst 050422

(All information courtesy of the instrument teams.)

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 22 Apr 05 08:07:26 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     115214,   Seg_Num: 0
GRB_RA:          324.4306d {+21h 37m 43s} (J2000),
                 324.4733d {+21h 37m 54s} (current),
                 324.0284d {+21h 36m 07s} (1950)
GRB_DEC:         +55.7844d {+55d 47' 04"} (J2000),
                 +55.8084d {+55d 48' 30"} (current),
                 +55.5585d {+55d 33' 31"} (1950)
GRB_ERROR:       5.8 [arcsec radius, statistical plus systematic]
GRB_INTEN:       56100.00 [arb]
GRB_SIGNIF:      5.09 [sigma]
GRB_DATE:        13482 TJD;   112 DOY;   05/04/22
GRB_TIME:        28469.37 SOD {07:54:29.37} UT
TAM[0-3]:        327.64 237.19 261.38 242.12
AMPLIFIER:       2
WAVEFORM:        135
SUN_POSTN:        30.11d {+02h 00m 25s}  +12.27d {+12d 16' 07"}
SUN_DIST:         66.28 [deg]
MOON_POSTN:      186.76d {+12h 27m 02s}   -1.25d {-01d 15' 03"}
MOON_DIST:       115.70 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:       98.03,  2.58 [deg] galactic lon,lat of the burst
ECL_COORDS:        3.61, 62.72 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        WARNING: XRT alignment calibration is on-going, and there may be  
COMMENTS:        residual systematic offsets of several arcseconds not accounted for yet  
COMMENTS:        by our on-board position determination algorithm.  We have increased  
COMMENTS:        the estimated error circle radius to take this into account.  
COMMENTS:        The 'object' found for this position is very likely a cosmic ray hit in the CCD; not a burst afterglow.

red DSS finding chart ps-file

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 22 Apr 05 08:08:10 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     115214,   Seg_Num: 0 
GRB_RA:          324.454d {+21h 37m 49s} (J2000),
                 324.497d {+21h 37m 59s} (current), 
                 324.052d {+21h 36m 13s} (1950) 
GRB_DEC:         +55.799d {+55d 47' 55"} (J2000),
                 +55.823d {+55d 49' 22"} (current),
                 +55.573d {+55d 34' 22"} (1950)
GRB_DATE:        13482 TJD;   112 DOY;   05/04/22
GRB_TIME:        28359.80 SOD {07:52:39.80} UT
TRIGGER_INDEX:   478
GRB_PHI:         -35.03 [deg]
GRB_THETA:        19.15 [deg]
DELTA_TIME:      71.00 [sec]
LC_URL:          sw00115214000msb.lc
SUN_POSTN:        30.10d {+02h 00m 25s}  +12.27d {+12d 16' 06"}
SUN_DIST:         66.27 [deg]
MOON_POSTN:      186.75d {+12h 26m 59s}   -1.24d {-01d 14' 35"}
MOON_DIST:       115.70 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:       98.05,  2.58 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        3.65, 62.72 [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/BACODINE POSITION NOTICE


TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 22 Apr 05 08:08:54 UT
NOTICE_TYPE:     Swift-XRT Lightcurve
TRIGGER_NUM:     115214,   Seg_Num: 0
POINT_RA:        324.431d {+21h 37m 43s} (J2000)
POINT_DEC:       +55.806d {+55d 48' 23"} (J2000)
LC_START_DATE:   13482 TJD;   112 DOY;   05/04/22
LC_START_TIME:   28472.11 SOD {07:54:32.11} UT
LC_STOP_DATE:    13482 TJD;   112 DOY;   05/04/22
LC_STOP_TIME:    28699.75 SOD {07:58:19.75} UT
LC_LIVE_TIME:    223.98 [sec], 98.4%
DELTA_TIME:      86172.36 [sec]
N_BINS:          100
TERM_COND:       0
LC_URL:          sw00115214000msx.lc
SUN_POSTN:        30.11d {+02h 00m 25s}  +12.27d {+12d 16' 07"}
SUN_DIST:         66.28 [deg]
MOON_POSTN:      186.76d {+12h 27m 02s}   -1.25d {-01d 15' 04"}
MOON_DIST:       115.69 [deg]
MOON_ILLUM:      95 [%]
GAL_COORDS:       98.04,  2.60 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:        3.64, 62.74 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-XRT Lightcurve.

GCN notice #3314
L. Barbier (GSFC), D. Palmer (LANL), D. Burrows (PSU), A. Blustin (MSSL), H. Krimm (GSFC/USRA), N. Gehrels (GSFC), K. McGowan (MSSL), M. Chester (PSU)
At 07:52:40 UT, the Swift Burst Alert Telescope (BAT) triggered and located on-board GRB050422 (trigger #115214). The BAT on-board calculated location is RA, dec 324.454, +55.799 (J2000) with an uncertainty of 4 arcmin (radius, 3-sigma, including estimated systematic uncertainty). The BAT light curve showed a multipeak structure with a duration of about 60 seconds. The peak count rate measured by BAT was about 1000 counts/sec in the 15 - 350 keV band, occurring 50 seconds after the trigger.
The Swift spacecraft slewed at about T+60 seconds onto the BAT position. No BAT position message was received from TDRSS due to the fact that the burst occurred during a Malindi pass.
The spacecraft executed a prompt slew and the XRT began taking data on the target at 07:54:29.4 UT. The XRT image looks like a cosmic ray hit, not a real source. Therefore the XRT position may be incorrect. However, the XRT spectra and lightcurve look like there is a real source in the field of view. Verification of the XRT position will require analysis of ground-processed data following the next ground station pass.
The Swift Ultra Violet/Optical (UVOT) observations began at 07:54:32.2 UT, 112 seconds after the BAT trigger. The first data taken after the spacecraft settled was a 100 sec exposure using the V filter with the midpoint of the observation at 162 sec after the BAT trigger. This image was sent directly to the ground via TDRSS with the FOV pixel binning set at 8x8 pixels to reduce telemetry. A comparison against the Digitized Sky Survey reveals no new source inside the BAT error circles at RA, dec 324.454, 55.799 (J2000) with a radius of 4 arcmin.
GCN notice #3315
C. Pagani (INAF-OAB), D. N. Burrows (PSU), A. P. Beardmore (U. Leicester), and N. Gehrels (GSFC) report on behalf of the Swift XRT team:
The Swift BAT instrument detected a GRB at 07:52:40 UT on 22nd April 2005 (GCN Circ 3314). The spacecraft executed a prompt slew and the XRT began taking data on the target at 07:54:29.4 UT. Due to the presence of a cosmic ray in the initial image the on-board software could not properly centroid on the GRB, and the position generated on-board and sent out automatically through BACODINE was incorrect (the Notice indicated that this position was probably a cosmic ray). From ground processed data we find a uncataloged, rapidly X-ray source within the BAT error circle, located at:
```
RA(J2000) = 21:37:54.5,
Dec(J2000) = +55:46:46.6.
```
We estimate an uncertainty of about 5 arcseconds radius (90% containment). This position is 84 arcseconds from the BAT position reported in GCN 3314.
GCN notice #3316
M. Suzuki (Saitama), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC), J. Cannizzo (GSFC/UMBC), M. Ajello (MPE), M. Chester (PSU) on behalf of the Swift/BAT team:
At 07:52:39 UT Swift-BAT detected GRB 050422 (trigger= 115214) (GCN Circ 3314, Barbier et al.). The refined BAT ground position is (RA,Dec) = 324.454, 55.798, [deg; J2000] +- 3 arcmin, (95% containment). The partial coding was 98%.
The light curve shows multiple peaks, with the main peak starting about T+42 seconds after the trigger and with another hard peak at T+102 seconds. T90 (15-350 keV) is (59.2 +- 0.3) seconds (estimated error including systematics).
The photon index of the time-averaged spectrum is 1.4 +- 0.2. The fluence in the 15-350 keV band is (1.2 +- 0.2) x 10^-6 erg/cm2. The 1-s peak photon flux measured from T0+53.1 seconds in the 15-350 band is (0.7 +- 0.1 ) ph/cm2/s. All the quoted errors are at the 90% confidence level.
GCN notice #3317
K. McGowan (MSSL), A. Blustin (MSSL), S. Rosen (MSSL), L. Barbier (GSFC), S. Hunsberger (PSU), M. Still (GSFC), P. Smith (MSSL), N. Gehrels (GSFC), K. Mason (MSSL), J. Nousek (PSU), on behalf of the Swift UVOT team
Starting with the data taken ~113s after the BAT trigger (Barbier et al, GCN 3314) we have co-added the data of GRB 050422 in each of the Ultra-Violet/Optical Telescope (UVOT) V, B and U bands. The co-added image for the V-band is made up of 1 x 100 s and 5 x 10 s exposures, the co-added B-band and U-band images are made up of 5 x 10 s exposures. The XRT error circle (Pagani et al., GCN 3315) falls partially on a known source from the DSS. No new source is detected in any of the bands; we estimate the five sigma magnitude upper limits from the co-added images to be:
```
Filter  Upper Limit  Duration(s)  T_start(s)  T_mid(s)
   V        17.9        148.7        112.9      374.1
   B        18.2         48.8        258.6      432.5
   U        17.8         48.8        244.5      418.0
```
Where T_start is time after trigger, and T_mid is the midpoint of the summed exposure.
The magnitudes are based on preliminary zero-points, measured in orbit, and will require refinement with further calibration.
We note that the reddening in this direction is E_{B-V} = 1.4.

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Jochen Greiner, last update: 22-Apr-2005 [Disclaimer]