Gamma-ray Burst 020625

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/HETE BURST POSITION NOTICE
NOTICE_DATE:    Tue 25 Jun 02 11:36:07 UT
NOTICE_TYPE:    HETE S/C_Alert
TRIGGER_NUM:    2081,   Seq_Num: 1
GRB_DATE:       12450 TJD;   176 DOY;   02/06/25
GRB_TIME:       41149.33 SOD {11:25:49.33} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
GAMMA_RATE:     134  [cnts/s]  on a 5.200 [sec] timescale
SC_LONG:        160 [deg East]
SUN_POSTN:       94.08d {+06h 16m 19s}  +23.39d {+23d 23' 08"}
MOON_POSTN:     281.92d {+18h 47m 41s}  -25.14d {-25d 08' 07"}
MOON_ILLUM:     100 [%]
COMMENTS:       No s/c ACS pointing info available yet.
COMMENTS:       Probable GRB.

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/HETE BURST POSITION NOTICE
NOTICE_DATE:    Tue 25 Jun 02 14:19:24 UT
NOTICE_TYPE:    HETE Ground Analysis
TRIGGER_NUM:    2081,   Seq_Num: 3
GRB_DATE:       12450 TJD;   176 DOY;   02/06/25
GRB_TIME:       41149.32 SOD {11:25:49.32} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
GAMMA_RATE:     134  [cnts/s]  on a 5.200 [sec] timescale
SC_-Z_RA:       273 [deg]
SC_-Z_DEC:      -23 [deg]
SC_LONG:          0 [deg East]
WXM_CNTR_RA:    310.928d {+20h 43m 43s} (J2000),
                310.958d {+20h 43m 50s} (current),
                310.313d {+20h 41m 15s} (1950)
WXM_CNTR_DEC:    +7.089d {+07d 05' 21"} (J2000),
                 +7.098d {+07d 05' 54"} (current),
                 +6.908d {+06d 54' 29"} (1950)
WXM_CORNER1:    310.6549   7.2290 [deg]
WXM_CORNER2:    310.9020   7.3880 [deg]
WXM_CORNER3:    311.2010   6.9500 [deg]
WXM_CORNER4:    310.9529   6.7900 [deg]
WXM_MAX_SIZE:   27.57 [arcmin] diameter
WXM_LOC_SN:     9 sig/noise (pt src in image)
WXM_IMAGE_SN:   X= 0.0 Y= 0.0 [sig/noise]
WXM_LC_SN:      X= 0.0 Y= 0.0 [sig/noise]
SUN_POSTN:       94.08d {+06h 16m 19s}  +23.39d {+23d 23' 08"}
SUN_DIST:       132.81 [deg]
MOON_POSTN:     281.92d {+18h 47m 41s}  -25.14d {-25d 08' 07"}
MOON_DIST:       42.86 [deg]
MOON_ILLUM:     100 [%]
GAL_COORDS:     53.17,-21.06 [deg] galactic lon,lat of the burst
ECL_COORDS:     315.50,24.30 [deg] ecliptic lon,lat of the burst
COMMENTS:       Probable GRB.
COMMENTS:       Burst_Validity flag is true.
COMMENTS:       WXM data refined since S/C_Last Notice.

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/HETE BURST POSITION NOTICE
NOTICE_DATE:    Tue 25 Jun 02 15:16:17 UT
NOTICE_TYPE:    HETE Ground Analysis
TRIGGER_NUM:    2081,   Seq_Num: 4
GRB_DATE:       12450 TJD;   176 DOY;   02/06/25
GRB_TIME:       41149.32 SOD {11:25:49.32} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
GAMMA_RATE:     134  [cnts/s]  on a 5.200 [sec] timescale
SC_-Z_RA:       273 [deg]
SC_-Z_DEC:      -23 [deg]
SC_LONG:          0 [deg East]
WXM_CNTR_RA:    311.060d {+20h 44m 14s} (J2000),
                311.090d {+20h 44m 22s} (current),
                310.446d {+20h 41m 47s} (1950)
WXM_CNTR_DEC:    +7.170d {+07d 10' 12"} (J2000),
                 +7.179d {+07d 10' 45"} (current),
                 +6.988d {+06d 59' 18"} (1950)
WXM_CORNER1:    310.7870   7.3090 [deg]
WXM_CORNER2:    311.0340   7.4690 [deg]
WXM_CORNER3:    311.3330   7.0310 [deg]
WXM_CORNER4:    311.0860   6.8710 [deg]
WXM_MAX_SIZE:   27.57 [arcmin] diameter
WXM_LOC_SN:     9 sig/noise (pt src in image)
WXM_IMAGE_SN:   X= 0.0 Y= 0.0 [sig/noise]
WXM_LC_SN:      X= 0.0 Y= 0.0 [sig/noise]
SUN_POSTN:       94.08d {+06h 16m 19s}  +23.39d {+23d 23' 08"}
SUN_DIST:       132.65 [deg]
MOON_POSTN:     281.92d {+18h 47m 41s}  -25.14d {-25d 08' 07"}
MOON_DIST:       43.01 [deg]
MOON_ILLUM:     100 [%]
GAL_COORDS:     53.31,-21.12 [deg] galactic lon,lat of the burst
ECL_COORDS:     315.67,24.34 [deg] ecliptic lon,lat of the burst
COMMENTS:       Probable GRB.
COMMENTS:       Burst_Validity flag is true.
COMMENTS:       WXM data refined since S/C_Last Notice.

GCN notice #1441
P.A. Price, B.P. Schmidt, T.S. Axelrod (RSAA, ANU) and J.S. Bloom (CfA) report:
We have observed the error-circle of HETE Trigger #2081 with the robotic MSO 50-inch telescope at 2002 Jun 25.65 UT. Exposures consisted of 3x300 sec integrations in MACHO R, and cover the entire error circle. We do not identify any afterglow candidate on visual comparison with the DSS2 to a limit approximately R ~ 19.5 mag.
This message may be cited.
GCN notice #1442
G. Ricker, J-L Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf of the HETE Science Team;
N. Butler, J. Doty, R. Vanderspek, J. Villasenor, G. Crew, G. Monnelly, T. Cline, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of the HETE Operations and HETE Optical-SXC Teams;
Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, and T. Donaghy, on behalf of the HETE WXM Team;
M. Boer, J-F Olive, J-P Dezalay, and K. Hurley on behalf of the HETE FREGATE Team;
write:
At 11:25:49.32 UTC (41149.32 s UT) on 25 June 2002, the HETE FREGATE instrument detected event H2081. This event, which triggered FREGATE in Band C (30-400 keV), was very hard: the event is strongly evident (SNR ~ 12) in FREGATE Band C and is evident in FREGATE Band B (6-80 keV), but is barely visible, if at all, in FREGATE Band A (6-40 keV) and in the WXM 2-25 keV energy band.
A second event occurred 86 sec later. This event was much softer: it is barely visible in FREGATE Band C, but is discernible in FREGATE bands A and B. This second event is also strongly evident in the WXM 2-25 keV energy band (SNR ~ 8). Triggers on the WXM data are currently off in order to avoid inundating the astronomical community with XRB triggers, and therefore no WXM flight location was calculated for this event.
The probability of the HETE FREGATE and WXM instruments detecting two separate GRBs within 100 sec is very small. We therefore interpret the two events as part of a single, long GRB, consisting of two main peaks and having a duration > 125 sec.
No real-time spacecraft aspect was available because of the full moon (99% illumination). Ground analysis produced a location, using the spacecraft aspect at the time of trigger H2081 (corresponding to the beginning of the first peak), that was reported in a GCN Position Notice at 14:19:24 UT, 173 min after the burst. Further ground analysis revealed that the spacecraft had drifted by an unusually large amount (~10 arcminutes) during the burst. Therefore a refined location, using the spacecraft aspect at the time of the second peak, which could be localized using WXM data, was reported in a second GCN Position Notice at 15:16:17 UT, 230 min after the burst. The refined location can be expressed as a 90% confidence rectangle that is 18 arcminutes by 32 arcminutes. The center and the corners of the rectangle lie at the following J2000 coordinates:
```
RA = 20h 44m 14s, Dec = +07o 10' 12" (center)
RA = 20h 43m 09s, Dec = +07o 18' 32" (corner)
RA = 20h 44m 08s, Dec = +07o 28' 08" (corner)
RA = 20h 45m 20s, Dec = +07o 01' 52" (corner)
RA = 20h 44m 21s, Dec = +06o 52' 16" (corner).
```
The first peak of GRB020625 had a peak flux >6 Crab and a duration of ~20 sec in FREGATE Band C (30-400 keV), during which a total of 1200 net counts were detected. The second peak had a peak flux ~2.0 x 10^-8 ergs cm-2 s-1 (i.e., ~1 x Crab flux) averaged over 1.2 sec and a duration of ~17 sec in FREGATE Band A (6-40 keV). During this time interval a total of 830 net counts were detected, corresponding to a fluence of ~1.5 x 10^-7 ergs cm-2. In the WXM 2-25 keV band, the second peak had a duration of 25 seconds. The WXM localization SNR was ~9.
Further information (including a light curve) for GRB020625 is provided at the following URL:
http://space.mit.edu/HETE/Bursts/
This message is citable.
GCN notice #1444
V.Burnashev (CrAO), V.Rumyantsev (CrAO) and A.Pozanenko (IKI) report:
We have imaged of the error box for GRB 020625 / HETE #2081 with the 0.70-m Cassegrain telescope of Crimean Astrophysical Observatory (field 15x15 arcminutes).
We obtained several frames which include the center of error box and partially covered its area on 2002 Jun. 25.9138 (10.5h after the burst) - 25.9861 UT.
We do not identify any afterglow candidate on visual comparison with the DSS2 to a limit approximately R ~ 18.2 mag.
This message may be cited.
GCN notice #1445
GRB 020625, optical observations ---------------------------------
Alberto Castro-Tirado (IAA-CSIC, Granada) Javier Méndez (ING Group, La Palma) Pilar Ruiz Lapuente (Univ. de Barcelona) Javier Gorosabel (IAA-CSIC, Granada) José María Castro Cerón (ROA, San Fernando)
report:
"We have obtained several images in the Sloan i'-band filter following the detection by HETE of GRB 020625 (Ricker et al. GCN 1442) with the 2.5-m Isaac Newton Telescope (+WFC) at La Palma. The observations started 16.3 hr after the event and cover 90 % of the HETE error box. Details follow:
```
Date  (UT time)            Frames    Seeing   Limiting Mag
-----------------------------------------------------------
June 26, 03:42-04:22     4 x 600-s    1".8      20.5
June 27, 03:39-03:49     1 x 600-s    0".9      21.0
June 28, 23:47-00:10     2 x 600-s    1".2      21.0
```
No sources varying by more than 0.3 mag were seen within the fraction of the HETE error box imaged at the INT. This complements the upper limits given by Burnashev et al. (GCN 1444). Further observations are planned."

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Jochen Greiner, last update: 05-Jul-2002 [Disclaimer]