Gamma-ray Burst 000508B

On May 8, 2000 at 19:13 UT RXTE's ASM detected a burst (BATSE trigger 8098) while coming out of out of Earth-occult. This burst was also seen by Ulysses, and thus a small error box could be derived.

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• BACODINE_FINAL_POSITION
  

  TITLE:         BACODINE FINAL BURST POSITION NOTICE
  NOTICE_DATE:   Mon 08 May 00 19:12:28 UT
  NOTICE_TYPE:   Final
  TRIGGER_NUM:   8098
  GRB_RA:        261.48d {+17h 25m 56s} (J2000),
                 261.49d {+17h 25m 58s} (current),
                 260.71d {+17h 22m 51s} (1950)
  GRB_DEC:       -25.35d {-25d 20' 58"} (J2000),
                 -25.35d {-25d 21' 00"} (current),
                 -25.31d {-25d 18' 23"} (1950)
  GRB_ERROR:     1.7 [deg radius, statistical only]
  GRB_FLUENCE:   30487 [cnts]    Peak=4024 [cnts/sec]  Del_t=6.4 [sec]
  GRB_TIME:      69050.87 SOD {19:10:50.87} UT
  GRB_DATE:      11672 TJD;   129 DOY;   00/05/08
  GRB_SC_AZ:     149.64 [deg]                        {XScan=3.44}
  GRB_SC_EL:     -83.19 [deg]  {Zenith_angle=173.19}  {Scan=-174.12}
  SC_X_RA:       357.74 [deg] (J2000)
  SC_X_DEC:        0.50 [deg]
  SC_Z_RA:        87.94 [deg]
  SC_Z_DEC:       21.98 [deg]
  SUN_POSTN:      46.03d {+03h 04m 06s}  +17.33d {+17d 19' 43"}
  SUN_DIST:      146.12 [deg]
  MOON_POSTN:    113.38d {+07h 33m 31s}  +21.09d {+21d 05' 18"}
  MOON_DIST:     150.46 [deg]
  PROG_VERSION:  5.33
  PROG_LEVEL:    1
  COMMENTS:      Definite GRB.  
  COMMENTS:      This notice is based on 12 1.024-sec samples of the light curve.
  

• GCN/RXTE_ASM_GRB_POSITION
  

  TITLE:                    GCN/RXTE_ASM BURST POSITION NOTICE
  NOTICE_DATE:              Mon 08 May 00 23:23:09 UT
  NOTICE_TYPE:              RXTE-ASM Initial
  TRIGGER_NUM:              8098
  GRB_DATE:                 11672 TJD;   129 DOY;   00/05/08
  GRB_TIME:                 69050.88 SOD {19:10:50.88} UT
  POSITION_TYPE:            Line
  GRB_RXTE_RA:              248.756d {+16h 35m 01s} (J2000),
                            248.761d {+16h 35m 03s} (current),
                            248.008d {+16h 32m 02s} (1950)
  GRB_RXTE_DEC:             -22.672d {-22d 40' 18"} (J2000),
                            -22.673d {-22d 40' 21"} (current),
                            -22.569d {-22d 34' 09"} (1950)
  GRB_RXTE_ERROR:           10.000 [deg half-length (stat+sys),90%]
  GRB_RXTE_LINE_LENGTH:     11.500 [deg]
  GRB_RXTE_LINE_WIDTH:      0.077 [deg]
  GRB_RXTE_LINE_POS_ANGLE:  64.400 [deg]
  GRB_RXTE_INTEN:           330.00 [mCrab]
  SUN_POSTN:                 46.03d {+03h 04m 06s}  +17.33d {+17d 19' 43"}
  SUN_DIST:                 158.01 [deg]
  MOON_POSTN:               113.38d {+07h 33m 31s}  +21.09d {+21d 05' 18"}
  MOON_DIST:                138.72 [deg]
  COMMENTS:                 RXTE-ASM GRB Coordinates.  
  COMMENTS:                 This GRB was only seen in one camera.  
  COMMENTS:                 Due to missing anodes, we can poorly constrain the  
  COMMENTS:                 position of the GRB along the long direction of the  
  COMMENTS:                 error box.  From the given position, the box should  
  COMMENTS:                 extend 10 degrees to the north east, and 1.5 degrees
  COMMENTS:                 to the south west.  
  COMMENTS:                   
  COMMENTS:                 This was a complex observation to analyze. It appears
  COMMENTS:                 that the GRB came out of earth-occult in progress  
  COMMENTS:                 at around 19:13:40 UTC.  The average flux over the  
  COMMENTS:                 full 90-s observation was 330 mCrab (2-12 keV), but  
  COMMENTS:                 we only observed the burst for around 20 s.  The   
  COMMENTS:                 maximum flux may have exceeded 2 Crab.
  COMMENTS:                   
  COMMENTS:                 The ASM position passes 5' outside the nominal 0.4deg
  COMMENTS:                 radius LOCBURST position reported by BATSE.
  

• GCN/RXTE_ASM_GRB_POSITION
  

  TITLE:                    GCN/RXTE_ASM BURST POSITION NOTICE
  NOTICE_DATE:              Tue 09 May 00 19:05:10 UT
  NOTICE_TYPE:              RXTE-ASM Update
  TRIGGER_NUM:              8098
  GRB_DATE:                 11672 TJD;   129 DOY;   00/05/08
  GRB_TIME:                 69050.88 SOD {19:10:50.88} UT
  POSITION_TYPE:            Box
  GRB_RXTE_RA:              253.498d {+16h 53m 60s} (J2000),
                            253.503d {+16h 54m 01s} (current),
                            252.758d {+16h 51m 02s} (1950)
  GRB_RXTE_DEC:             -20.504d {-20d 30' 13"} (J2000),
                            -20.505d {-20d 30' 15"} (current),
                            -20.423d {-20d 25' 22"} (1950)
  GRB_ERROR_RA1:            254.326d {+16h 57m 18s} (J2000)
  GRB_ERROR_DEC1:           -20.130d {-20d 07' 47"} (J2000)
  GRB_ERROR_RA2:            256.674d {+17h 06m 42s} (J2000)
  GRB_ERROR_DEC2:           -20.362d {-20d 21' 42"} (J2000)
  GRB_ERROR_RA3:            252.669d {+16h 50m 41s} (J2000)
  GRB_ERROR_DEC3:           -20.850d {-20d 51' 00"} (J2000)
  GRB_ERROR_RA4:            253.313d {+16h 53m 15s} (J2000)
  GRB_ERROR_DEC4:           -20.618d {-20d 37' 04"} (J2000)
  GRB_RXTE_ERROR:           0.900 [deg radius (stat+sys), 90%]
  GRB_RXTE_INTEN:           300.00 [mCrab]
  SUN_POSTN:                 46.03d {+03h 04m 06s}  +17.33d {+17d 19' 43"}
  SUN_DIST:                 153.85 [deg]
  MOON_POSTN:               113.38d {+07h 33m 31s}  +21.09d {+21d 05' 18"}
  MOON_DIST:                142.82 [deg]
  COMMENTS:                 RXTE-ASM GRB Coordinates.  
  COMMENTS:                 Further analysis has revealed a detection of this  
  COMMENTS:                 GRB in the second dwell after its emergence from  
  COMMENTS:                 behind the Earth.  We report here the joint position
  COMMENTS:                 of these two lines of position.
  

• GCN notice #665
  D. A. Smith and A. M. Levine (MIT), K. Hurley (UCB), and S. Barthelmy (NASA/GSFC) report on behalf of the RXTE/ASM teams at MIT and NASA/GSFC and the IPN collaboration:
  The RXTE All-Sky Monitor has detected emission we associate with GRB 000508B (BATSE #8098). One camera of the ASM was advantageously placed to observe the field around the BATSE LOCBURST position within 200 seconds of the trigger time (19:10:50.88 UTC). A dramatic rise in intensity occured over approximately 10 s, to a peak of ~1.5 Crab (2-12 keV) at roughly 19:13:44, 75 s into a 90-s ASM observation. Analysis of the position histogram data shows evidence for a previously unknown X-ray source in this and the next sequential observation, after the camera was rotated through six degrees.
  Localizations of these two detections yields an error box in the shape of a long, thin parallelogram centered at R.A. = 253.498d, Decl. = -20.504d (J2000). This position is confirmed by an annulus derived via the IPN through detections by BATSE and Ulysses. The preliminary annulus is 9.67' in width (3sigma), with a radius of 76.512 deg, centered at R.A. = 309.088, Decl. = 35.112 (J2000.0). This annulus intersects the above diamond at the following points, creating a joint error box with area ~46 sq. arcmin.:

  253.700d {16h 54m 48s} -20.432d {-20d 25' 55"}
  253.643d {16h 54m 34s} -20.380d {-20d 22' 48"}
  253.483d {16h 53m 56s} -20.456d {-20d 27' 22"}
  253.5383 {16h 54m 09s} -20.511d {-20d 30' 40"}
  

  The time of the increase in the count rate in the first ASM observation is consistent with the estimated time that the best-fit location for the GRB rose from behind the Earth's limb, so we attribute the characteristics of the rise and the lack of detectable emission prior to this time to Earth occultation, not to any intrinsic properties of the GRB source.
  See the web page at http://xte.mit.edu/grb000508b/ for images and further commentary. The image is reproduced below:

• GCN/IPN Notice for GRB000508A
  

  TITLE:          GCN/IPN LOCALIZATION
  NOTICE_TYPE:    Original (based on the BATSE-Original location)
  NOTICE_DATE:    Tue May  9 23:50:36 GMT 2000
  TRIGGER_NUM:    8098
  GRB_DATE:       00/05/08
  GRB_TIME:       19:10:50.87 UT
  BACO_RA:        260.49d {+17h 21m 59s}   (J2000)
  BACO_DEC:       -24.68d {-24d 40' 46"}
  BACO_ERR:       9.0 [degees radius, statistical only]
  HUNT_RA:        ???.??d {??h ??m ??s}   (J2000)
  HUNT_DEC:        ??.??d {??d ??' ??}
  HUNT_ERR:       ?.? [degees radius, statistical plus systematic]
  B_H_DELTA:      ?.?? [deg]
  BACO_SC_AZ:     157.58 [deg]
  BACO_SC_EL:     -82.64 [deg]  {Zen_angle=}
  SUN_POSTN:      46.03d {+03h 04m 06s}   +17.33d {+17d 19' 43"}   (Current)
  SUN_B_DIST:     147.08 [deg]
  MOON_POSTN:     113.38d {+07h 33m 31s}   +21.09d {+21d 05' 18"}   (Current)
  MOON_B_DIST:    149.57 [deg]
  ANNULUS_RA:     309.0879d {}   (J2000)
  ANNULUS_DEC:    35.1118d {}
  ANNULUS_RADIUS: 76.512 [deg]
  ANNULUS_WIDTH:  [deg]  (Total width)
  COMMENTS:       Definite GRB. 
  COMMENTS:       This notice is based on 2 1.024-sec samples of the light curve.
  COMMENTS:       This report is based only on the BATSE-Original and IPN
  COMMENTS:       information as input.  There is no Huntville input
  COMMENTS:       at this early stage of processing.
  COMMENTS:       Multi-peaked event.  Duration ~60sec.
  COMMENTS:       Weakly detected above 300 keV.
  

  This IPN localization is preliminary. The "total width" of the annulus was selected to include all known uncertainties and systematics. The final analysis will reduce this width. All follow-up queries should be addressed to Kevin Hurley (UC Berkeley, khurley@sunspot.ssl.berkeley.edu).
  The center of the IPN annulus is tabulated below along the segment that intersects the Huntsville error circle. The Distance column is the sky-angle distance between the BACODINE location and the sampled position on the arc segment. The position of maximum probability plus the 1-, 2-, & 3-sigma containment probabilities (statistical+systematic) are marked.
  A detailed description of the format, content, and meaning of this document is given in the URL: http://gcn.gsfc.nasa.gov/gcn/ipn.html

       (J2000)
     RA       DEC       Distance
  
   287.372  128.715    26.68   <=== +3-sigma probability
   286.836  128.576    26.24
   286.302  128.434    25.80
   285.770  128.289    25.36
   285.241  128.140    24.92
   284.713  127.988    24.48
   284.188  127.833    24.04
   283.665  127.674    23.60
   283.144  127.513    23.16
   282.625  127.348    22.72
   282.108  127.180    22.28
   281.594  127.009    21.83
   281.081  126.834    21.39
   280.571  126.657    20.95
   280.064  126.476    20.50
   279.558  126.293    20.06
   279.055  126.106    19.61
   278.553  125.916    19.17
   278.055  125.723    18.72
   277.558  125.527    18.27
   277.064  125.328    17.83   <=== +2-sigma probability
   276.571  125.126    17.38
   276.082  124.921    16.93
   275.594  124.713    16.48
   275.109  124.502    16.03
   274.626  124.288    15.58
   274.145  124.071    15.13
   273.667  123.851    14.68
   273.191  123.628    14.23
   272.717  123.402    13.78
   272.245  123.174    13.32
   271.776  122.942    12.87
   271.309  122.708    12.42
   270.845  122.471    11.96
   270.383  122.231    11.51
   269.923  121.989    11.05
   269.465  121.743    10.60
   269.010  121.495    10.14
   268.557  121.244     9.68
   268.106  120.991     9.22
   267.658  120.734     8.77   <=== +1-sigma probability
   267.212  120.476     8.31
   266.768  120.214     7.85
   266.327  119.950     7.39
   265.888  119.683     6.93
   265.451  119.414     6.47
   265.016  119.142     6.02
   264.584  118.868     5.56
   264.154  118.591     5.10
   263.727  118.311     4.64
   263.301  118.030     4.19
   262.878  117.745     3.74
   262.457  117.459     3.29
   262.038  117.170     2.85
   261.622  116.878     2.42
   261.208  116.584     2.01
   260.796  116.288     1.63
   260.386  115.990     1.31
   259.979  115.689     1.11
   259.573  115.386     1.09
   259.573  115.386     1.09   <=== Max probability
   259.573  115.386     1.09
   259.170  115.081     1.26
   258.769  114.774     1.57
   258.371  114.464     1.94
   257.974  114.153     2.35
   257.579  113.839     2.78
   257.187  113.523     3.23
   256.797  113.205     3.68
   256.408  112.885     4.14
   256.022  112.563     4.61
   255.638  112.239     5.08
   255.256  111.913     5.55
   254.876  111.585     6.02
   254.498  111.255     6.49
   254.122  110.923     6.97
   253.748  110.589     7.44
   253.376  110.254     7.92
   253.006  109.916     8.40
   252.638  109.577     8.88
   252.272  109.236     9.36   <=== -1-sigma probability
   251.908  108.894     9.84
   251.545  108.549    10.33
   251.185  108.203    10.81
   250.826  107.855    11.29
   250.469  107.506    11.78
   250.114  107.154    12.26
   249.761  106.802    12.75
   249.410  106.447    13.23
   249.060  106.091    13.72
   248.712  105.734    14.21
   248.366  105.375    14.69
   248.021  105.015    15.18
   247.678  104.653    15.67
   247.337  104.289    16.16
   246.998  103.925    16.65
   246.660  103.559    17.14
   246.323  103.191    17.63
   245.988  102.822    18.12   <=== -2-sigma probability
   245.655  102.452    18.61
   245.323  102.080    19.10
   244.993  101.708    19.59
   244.664  101.334    20.08
   244.337  100.958    20.57
   244.011  100.582    21.06
   243.687  100.204    21.55
   243.364   99.825    22.05
   243.042   99.445    22.54
   242.722   99.064    23.03
   242.403   98.682    23.52
   242.086   98.299    24.02
   241.769   97.914    24.51
   241.454   97.529    25.01
   241.140   97.142    25.50
   240.828   96.755    25.99
   240.516   96.366    26.49
   240.206   95.977    26.98
   239.897   95.587    27.48   <=== -3-sigma probability
  

• GCN notice #667
  A. Henden (USRA/USNO) reports on behalf of the USNO GRB team:
  We have acquired preliminary shallow BVRc all-sky photometry for an 11x11 arcmin field that covers the error box for GRB000508B with the USNOFS 1.0-m telescope on one photometric night. Stars brighter than V=12 are saturated and should be used with care. We have placed the photometric data on our anonymous ftp site: ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb000508b.dat. The current photometry has a potential external zero-point error of about two percent. The astrometry in this file is based on linear plate solutions with respect to USNO-A2.0. The internal errors are less than 100mas. Further calibration of this field will be performed if an optical afterglow is identified.
• GCN notice #668
  K. Z. Stanek (CfA), P. M. Garnavich (Notre Dame), P. J. Groot, S. Jha (CfA) and M. Hicks (JPL) report:
  We have observed most of the RXTE/ASM-IPN error-box of GRB 000508B (GCN 665) using the FLWO 1.2-meter telescope on Mt. Hopkins and the KPNO 2.1m telescope. The center of the GRB 000508B error-box is located at Galactic coordinates (l,b)=(0.48 deg,14.38 deg), and the Schlegel et al. (1998) Galactic reddening toward this direction is E(B-V)=0.51 (A_V=1.7 mag). Due to the proximity to the Galactic plane the stellar field is fairly dense.
  At KPNO we obtained four 600 sec R-band images, the first two at UT May 10 07:30 and the second two at UT May 10 11:33. At FLWO we obtained two 600 sec R-band images, first one at UT May 10 06:39 and the second one at UT May 10 09:14. In addition, at FLWO we have obtained UBVI images for the field. Using DAOPHOT-II (Stetson 1992) on the FLWO 1.2-meter R-band image we detect about 5,000 objects with R<22.5 in 11x11 arcmin field.
  Visual comparison with the POSS-II red plate reveals no obvious ``new'' objects. Employing the image subtraction code ISIS-2 (Alard 1999) between the two epochs taken at each telescope reveals four possible variable objects located in the error-box, with the following coordinates and magnitudes from Henden et al. (GCN 667):

  V1) RA=253.58616  DEC=-20.41683  V=16.75
  
  V2) RA=253.54913  DEC=-20.46479  V=17.33
  
  V3) RA=253.53600  DEC=-20.43531  V=17.72
  
  V4) RA=253.60865  DEC=-20.42111  V=18.24
  

  All of these objects are easily identified on the POSS-II plate, so most likely NONE of these objects is the optical counterpart to GRB 000508B. Further observations are planned at FLWO.
• GCN notice #670
  B. L. Jensen, H. Pedersen, J. Hjorth (U. of Copenhagen), J. P. U. Fynbo (U. of Aarhus/ESO), J. Gorosabel, N. Lund (DSRI,Copenhagen), H. Kjeldsen, F. Grundahl (U. of Aarhus), C. Zurita, J. Casares (IAC,Tenerife), C. Sanchez-Fernandez and A.J. Castro-Tirado (LAEFF, Madrid) report on behalf of a larger European GRB collaboration:
  We have obtained images of the RXTE/IPN error box reported by Smith et al. (GCN #665) with the 2.56-m Nordic Optical Telescope (NOT+ALFOSC) on La Palma, and the 1.54-m Danish Telescope (DK-1.54m+DFOSC) at La Silla, as follows:

  Telescope      Date                  Filter/Exp t. FWHM
  NOT       2000 May 10.14 UT (t+32h); I:5x300s;     FWHM=0.8"
  DK-1.54m  2000 May 10.17 UT (t+33h); R:3x420s;     FWHM=1.5"
  DK-1.54m  2000 May 10.38 UT (t+38h); R:3x420s;     FWHM=1.5"
  DK-1.54m  2000 May 12.25 UT (t+83h); R:4x420s;     FWHM=1.3"
  

  We have visually compared the combined May 10 2520s R-band image with red POSS-II exposure. The three sets of May 10 images have been compared internally, both visually and using automated routines based on DAOPHOT II/ALLSTAR PSF-photometry. Additionally, we have compared the combined May 10 and May 12 R-band images, visually and through automated routines. We do not, in any of the comparisons, find any significantly variable objects down to a 3-sigma mag limit of R~22.5. We do not find significant variability in the objects noted by Stanek et al. (GCN #668). An image of the error-box is posted at http://www.astro.ku.dk/~brian_j/grb/grb000508B