Gamma-ray Burst 030725

(All information courtesy of the instrument teams.)

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Results of Observations

GCN/BACODINE POSITION NOTICE

  
TITLE:          GCN/HETE BURST POSITION NOTICE
NOTICE_DATE:    Fri 25 Jul 03 11:49:02 UT
NOTICE_TYPE:    HETE S/C_Alert 
TRIGGER_NUM:    2779,   Seq_Num: 1
GRB_DATE:       12845 TJD;   206 DOY;   03/07/25
GRB_TIME:       42384.82 SOD {11:46:24.82} UT 
TRIGGER_SOURCE: Trigger on the 6-120 keV band.
GAMMA_RATE:     562  [cnts/s]  on a 0.160 [sec] timescale
SC_-Z_RA:       327 [deg]      
SC_-Z_DEC:      -17 [deg]
SC_LONG:        238 [deg East]
SUN_POSTN:      124.41d {+08h 17m 37s}  +19.68d {+19d 40' 55"}
MOON_POSTN:      76.76d {+05h 07m 03s}  +24.59d {+24d 35' 17"}
MOON_ILLUM:     14 [%]
COMMENTS:       Probable GRB.

GCN/BACODINE POSITION NOTICE
```
  
```

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/HETE BURST POSITION NOTICE
NOTICE_DATE:    Fri 25 Jul 03 13:19:34 UT
NOTICE_TYPE:    HETE Ground Analysis
TRIGGER_NUM:    2779,   Seq_Num: 3
GRB_DATE:       12845 TJD;   206 DOY;   03/07/25
GRB_TIME:       42384.81 SOD {11:46:24.81} UT
TRIGGER_SOURCE: Trigger on the 6-120 keV band.
GAMMA_RATE:     562  [cnts/s]  on a 0.160 [sec] timescale
SC_-Z_RA:       326 [deg]
SC_-Z_DEC:      -17 [deg]
SC_LONG:        238 [deg East]
WXM_CNTR_RA:    308.392d {+20h 33m 34s} (J2000),
                308.457d {+20h 33m 50s} (current),
                307.482d {+20h 29m 56s} (1950)
WXM_CNTR_DEC:   -50.758d {-50d 45' 30"} (J2000),
                -50.746d {-50d 44' 45"} (current),
                -50.930d {-50d 55' 46"} (1950)
WXM_CORNER1:    308.4720 -51.0010 [deg]
WXM_CORNER2:    308.3140 -50.9840 [deg]
WXM_CORNER3:    308.3130 -50.5160 [deg]
WXM_CORNER4:    308.4700 -50.5330 [deg]
WXM_MAX_SIZE:   29.72 [arcmin] diameter
WXM_LOC_SN:     0 sig/noise (pt src in image)
WXM_IMAGE_SN:   X= 19.7 Y= 4.7 [sig/noise]
WXM_LC_SN:      X= 25.5 Y= 0.7 [sig/noise]
SUN_POSTN:      124.41d {+08h 17m 37s}  +19.68d {+19d 40' 55"}
SUN_DIST:       148.77 [deg]
MOON_POSTN:      76.76d {+05h 07m 03s}  +24.59d {+24d 35' 17"}
MOON_DIST:      132.75 [deg]
MOON_ILLUM:     14 [%]
GAL_COORDS:     348.23,-36.57 [deg] galactic lon,lat of the burst
ECL_COORDS:     297.24,-30.89 [deg] ecliptic lon,lat of the burst
COMMENTS:       Definite 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:    Fri 25 Jul 03 16:07:46 UT
NOTICE_TYPE:    HETE Ground Analysis
TRIGGER_NUM:    2779,   Seq_Num: 4
GRB_DATE:       12845 TJD;   206 DOY;   03/07/25  
GRB_TIME:       42384.80 SOD {11:46:24.80} UT
TRIGGER_SOURCE: Trigger on the 6-120 keV band.
GAMMA_RATE:     562  [cnts/s]  on a 0.160 [sec] timescale
SC_-Z_RA:       325 [deg]
SC_-Z_DEC:      -17 [deg] 
SC_LONG:        238 [deg East]
SXC_CNTR_RA:    308.444d {+20h 33m 47s} (J2000),
                308.509d {+20h 34m 02s} (current),
                307.534d {+20h 30m 08s} (1950)
SXC_CNTR_DEC:   -50.764d {-50d 45' 49"} (J2000),
                -50.752d {-50d 45' 05"} (current),
                -50.935d {-50d 56' 06"} (1950)
SXC_CORNER1:    308.4020 -50.9930 [deg]
SXC_CORNER2:    308.4889 -51.0030 [deg]
SXC_CORNER3:    308.4860 -50.5349 [deg]
SXC_CORNER4:    308.3990 -50.5250 [deg] 
SXC_MAX_SIZE:   28.87 [arcmin] diameter  
SXC_LOC_SN:     3 sig/noise (pt src in image)
SUN_POSTN:      124.41d {+08h 17m 37s}  +19.68d {+19d 40' 55"}
SUN_DIST:       148.76 [deg] 
MOON_POSTN:      76.76d {+05h 07m 03s}  +24.59d {+24d 35' 17"}
MOON_DIST:      132.72 [deg]
MOON_ILLUM:     14 [%]
GAL_COORDS:     348.22,-36.60 [deg] galactic lon,lat of the burst
ECL_COORDS:     297.28,-30.90 [deg] ecliptic lon,lat of the burst
COMMENTS:       Definite GRB. 
COMMENTS:       Burst_Validity flag is true.    
COMMENTS:       SXC data refined since S/C_Last Notice.

GCN notice #2322
GRB030725 (=H2779): A Bright GRB Localized by the HETE WXM and SXC
Y. Shirasaki, T. Tamagawa, M. Suzuki, C. Graziani, T. Donaghy, M. Matsuoka, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, Y. Nakagawa, R. Satoh, Y. Urata, T. Yamazaki and Y. Yamamoto, on behalf of the HETE WXM Team;
G. Ricker, J-L. Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf of the HETE Science Team;
G. Prigozhin, N. Butler, G. Crew, J. Doty, A. Dullighan, R. Vanderspek, J. Villasenor, T. Cline, J. G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Monnelly, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of the HETE Operations and HETE Optical-SXC Teams;
C. Barraud, M. Boer, J-F Olive, J-P Dezalay, and K. Hurley on behalf of the HETE FREGATE Team;
write:
At 11:46:24.82 UTC (42384.82 s UT) on 25 July 2003, the HETE FREGATE and WXM instruments detected GRB030725 (=H2779), a bright, double-peaked long GRB located at high galactic latitude (b = 37 degrees).
The burst triggered Fregate in the 5-120 keV energy band. A GCN burst alert was issued 2.6 m later. Because the source was located at the extreme edge of the FOV of the WXM Y counter, no flight localization was derived. Ground analysis of the WXM data provided a localization that was reported in a GCN Notice at 13:19:34 UT. The WXM localization can be expressed as a 90% confidence error region that is centered at:
WXM Center-ground: RA= 20h 33m 34s, Dec= -50d 45' 30" (J2000)
The WXM error region is unusually elongated because of the very low exposure of the Y detector. The four corners of the WXM error region are located at J2000 coordinates:
```
WXM_CORNER1:    	RA= 20h 33m 53.3s, Dec= -51d 00' 04"
WXM_CORNER2:    	RA= 20h 33m 15.3s, Dec= -50d 59' 02"
WXM_CORNER3:    	RA= 20h 33m 15.1s, Dec= -50d 30' 58"
WXM_CORNER4:    	RA=	20h 33m 52.8s, Dec= -50d 31' 59"
```
Ground analysis of the SXC data provided a better localization that was disseminated as a GCN notice at 16:07:46 UT. The SXC localization can be expressed as a 90% confidence error region that is centered at:
SXC Center-Ground: RA= 20h 33m 47s , Dec= -50d 45' 49" (J2000)
The SXC X camera detected the burst, but the SXC Y camera did not. We were able to use the WXM Y localization to constrain the SXC error region in the Y direction. The four corners of the SXC error region are located at J2000 coordinates:
```
SXC_CORNER1:    RA= 20h 33m 36.5s, Dec= -50d 59' 35"
SXC_CORNER2:    RA= 20h 33m 57.3s, Dec= -51d 00' 11"
SXC_CORNER3:    RA= 20h 33m 56.6s, Dec= -50d 32' 06"
SXC_CORNER4:    RA= 20h 33m 35.7s, Dec= -50d 31' 30"
```
H2779 was comprised by two FRED-like* peaks, separated by ~160s. The duration of the first peak was ~40s, while that of the second peak was ~10s. A total of 25000 counts were detected in the 7-30 keV energy band during the ~180s interval encompassing both peaks, corresponding to a fluence of ~5 x 10-6 ergs cm-2. The peak flux was >2 x 10-7 ergs cm-2 s-1 (ie >5 x Crab flux) in the same energy band. [* FRED = Fast rise, exponential decay]
In the 30-400 keV band, the fluence was ~2 x 10-5 ergs cm-2, which is ~4 times the fluence in the 7-30 keV band. Thus, H2779 appears to be a "classical" long hard burst.
A light curve and finding chart for GRB030725 is provided at the following URL:
http://space.mit.edu/HETE/Bursts/GRB030725
This message may be cited.

GCN notice #2324
Berto Monard of Bronberg Observatory, Pretoria South Africa reports, on behalf of the AAVSO International High Energy Network, the possible detection of an optical transient to GRB030725 (=H2779; Shirasaki et al., GCN 2322).

  The location of the OT is estimated to be (J2000)
  RA: 20 33 59.49
  Dec: -50 40 56.0

The OT shows a fading behavior (starting 7.1hrs after burst):

GRB030725   030725.788   18.8  Unfiltered with a red zeropoint
GRB030725   030725.848   19.0  Unfiltered with a red zeropoint
GRB030725   030725.938   19.6  Unfiltered with a red zeropoint

Objects from the UCAC1 catalog were used for photometry and astrometry.
The FTS images will be posted shortly to ftp.aavso.org in the grb/GRB030725 directory.
More details on the observation are below:

Contact name: Berto Monard
Contact e-mail: bmonard@mweb.co.za
Observer: Berto Monard / MLF
Site Name: Bronberg Observatory / CBA Pretoria
Nearest town: Pretoria / South Africa
Site latitude: 25deg 55min South
Site longitude: 28deg 27min East
Site elevation: 1590m
Telescope type: SCT / 30cm
Telescope focal ratio: f/4.2 effectively
CCD camera: SBIG ST-7E
CCD detector: KAF-0401E
CCD dimensions: 765x510 pixels
CCD pixel scale: 1.52 arcsec/pixel
F.O.V: 18 arcmin E-W x 12.5 arcmin N-S
GRB object name: GRB 030725
Observation date: 20030725 UT
Observation midpoint time: 18 55 UT  and 20 02 UT
Exposure time per frame: 45 sec
Number of stacked frames: 15 respectively 8
Filters used: unfiltered / CR
Processed: FF, DS, stacked
Estimated seeing: 3.0 arcsec FWHM
Limiting magnitude: 20.5CR estimated
Sky conditions: clear, fair seeing

Details of observations: a follow up on the previous report

The AAVSO International GRB network is greatful for a generous grant from the Curry Foundation and to NASA for the financial support for the High Energy Workshops for Amateur Astronomers.

GCN notice #2334
B. Monard (Bronberg Obs.) reports on behalf of the AAVSO International GRB network:
Additional observations of the HETE GRB030725 (=H2779; Shirasaki et al., GCN 2322) error circle were made with the Bronberg 0.30m telescope and unfiltered CCD. Many 45-second exposures with UT midpoint of 030728.724 were stacked, with a limiting magnitude of about 21CR (based on USNO-A red magnitudes).
The candidate optical transient located at
```
      20:33:59.49  -50:40:56.0 J2000
```
that was reported by Monard (GCN 2324) has now faded below our detection limit. This strengthens the assertion that this is the optical afterglow from GRB030725. The 030728 fits image will be uploaded to ftp://ftp.aavso.org/grb/GRB030725 later today.
We encourage observations by other sites.
The AAVSO International GRB network is greatful for a generous grant from the Curry Foundation and to NASA for the financial support for the High Energy Workshops for Amateur Astronomers.
GCN notice #2335
C. Vinter, S. Jorgensen (U. Copenhagen), J. Gorosabel (IAA-CSIC/STScI), J. Hjorth, B. L. Jensen (U. Copenhagen), J. P. U. Fynbo (U. Aarhus) report:
"We observed the optical transient (Monard, GCN ##2324,2334) located inside the HETE-2 error box of GRB 030725 (Shirasaki et al., GCN #2322) with the Danish 1.5-m telescope on July 29.38 2003. The optical transient is detected at R = 21.2 +- 0.2 (preliminary calibration, partly based on zero points from previous nights, partly on USNO-B1.0 reference stars). The resulting decay rate is quite slow, with an average power-law decay index of ~ -0.9 since the detection 7 hours after the burst (Monard GCN #2324)."
GCN notice #2337
K. Hurley and T. Cline, on behalf of the Ulysses, HETE, Mars Odyssey, and KONUS GRB teams,
I. Mitrofanov, S. Charyshnikov, V. Grinkov, A. Kozyrev, M. Litvak, and A. Sanin, on behalf of the HEND-Odyssey GRB team,
W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on behalf of the GRS/Odyssey GRB team,
E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team,
D. M. Smith, R. P. Lin, J. McTiernan, R. Schwartz, C. Wigger, W. Hajdas, and A. Zehnder, on behalf of the RHESSI GRB team,
A. von Kienlin, G. Lichti, and A. Rau, on behalf of the INTEGRAL SPI-ACS GRB team, and
G. Ricker, J-L Atteia, N. Kawai, D. Lamb, S. Woosley, J. Doty, R. Vanderspek, J. Villasenor, G. Crew, G. Monnelly, N. Butler, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, J. Braga, R. Manchanda, G. Pizzichini, Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, T. Donaghy, M. Boer, J-F Olive, and J-P Dezalay, on behalf of the HETE GRB team, report:
Ulysses, Mars Odyssey-GRS, Konus-Wind, RHESSI, INTEGRAL (SPI-ACS), and, of course, HETE-FREGATE, observed this GRB (H2779, GCN 2322). Because Ulysses, Earth, and Mars are practically aligned, a small error box cannot be derived for this burst by triangulation alone. However, five statistically independent annuli can be obtained for it. Their 3 sigma widths are 11.2' (Ulysses-Mars Odyssey), 8.0' (Ulysses-Konus), 5.3' (Ulysses-RHESSI), 4.2' (Ulysses-INTEGRAL), and 4.9' (Ulysses-HETE). All these annuli are consistent with, and reduce the area of, the HETE SXC 90% confidence error box given in GCN 2322. Although the optical transient reported by Henden (GCN 2324, 2334) lies slightly outside the 90% confidence SXC error box, it lies within all the IPN annuli, at distances from the centerlines corresponding to 0.6 sigma (Ulysses- Mars Odyssey), 2.3 sigma (Ulysses-Konus), 1.6 sigma (Ulysses-RHESSI), 1.6 sigma (Ulysses-INTEGRAL), and 0.7 sigma (Ulysses-HETE FREGATE).
The narrowest 3 sigma annulus (Ulysses-INTEGRAL) intersects the 90% confidence SXC error box to form an error box whose area is ~16 sq. arcmin., or a factor of ~5 smaller than the SXC error box. The intersection points are:
```
	RA(2000)	Decl.(2000)
	308.487		-50.701
	308.486		-50.586
	308.415		-50.527
	308.400		-50.629
```
A map will be posted shortly at ssl.berkeley.edu/ipn3/030725
GCN notice #2344
S. F. Jorgensen, C. Vinter (U. Copenhagen), A. Cassan (IAP, Paris), B. L. Jensen (U. Copenhagen), J. Gorosabel (IAA-CSIC/STScI), J. P. U. Fynbo (U. Aarhus), J. Hjorth, K. Pedersen (U. Copenhagen) report:
"We have obtained R-band observations of the the candidate optical afterglow of GRB 030725 (Monard, GCN ##2324,2334; Vinter et al. GCN #2335) with the Danish 1.5m telescope at La Silla. The late R-band light curve (Jul 29.3 - Aug 6.3 2003 UT) is well-fitted by a power law decay with index -1.4 +- 0.1. The optical transient is now R ~ 23."
GCN notice #2384
Magellan Observations of GRB030725 (=H2779)
A. Dullighan, N. Butler, R. Vanderspek, J. Villasenor, and G. Ricker (MIT)
write:
We have observed the optical counterpart (Monard, GCN 2324) of the HETE-discovered Gamma Ray Burst GRB030725(=H2779; Shirasaki et al, GCN 2322) with the MagIC instrument on the 6.5m Magellan Clay telescope at Las Campanas Observatory in Chile. Two 300 second, Sloan r-band exposures were taken in an interval centered on August 1.305 UT, at 6.81 days after the burst. Another two 360 sec Sloan r-band exposures were taken on August 2.166 UT, at 7.68 days after the burst. Date UT r Magnitude August 1.305 22.25 +/- 0.05 August 2.166 22.55 +/- 0.05 These measurements are consistent with the late time decay slope of -1.4 +/- 0.1 as reported by Jorgensen, et al. (GCN 2344).
A lightcurve for the optical afterglow of GRB 030725 can be seen at:
http://space.mit.edu/HETE/Bursts/GRB030725/
This message may be cited.

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Jochen Greiner, last update: 16-Sep-2003 [Disclaimer]