Gamma-ray Burst 000115

On January 15, 2000, 14:49:32 UT a rather bright X-ray burst was detected by BATSE (trigger 7954). A subsequent scanning observation with RXTE/PCA revealed a new X-ray source. A second, later observation proved the fading of this X-ray source, strongly suggesting the X-ray counterpart nature.

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

BACODINE_FINAL_POSITION

TITLE:         BACODINE FINAL BURST POSITION NOTICE
NOTICE_DATE:   Sat 15 Jan 00 14:50:41 UT
NOTICE_TYPE:   Final
TRIGGER_NUM:   7954
GRB_RA:        132.71d {+08h 50m 50s} (J2000),
               132.71d {+08h 50m 50s} (current),
               132.28d {+08h 49m 08s} (1950)
GRB_DEC:       -46.10d {-46d 05' 58"} (J2000),
               -46.10d {-46d 06' 00"} (current),
               -45.91d {-45d 54' 41"} (1950)
GRB_ERROR:     0.2 [deg radius, statistical only]
GRB_FLUENCE:   188819 [cnts]    Peak=51047 [cnts/sec]  Del_t=10.9 [sec]
GRB_TIME:      53372.02 SOD {14:49:32.02} UT
GRB_DATE:      11558 TJD;    15 DOY;   00/01/15
GRB_SC_AZ:     101.28 [deg]                        {XScan=66.27}
GRB_SC_EL:     -21.01 [deg]  {Zenith_angle=111.01}  {Scan=-153.01}
SC_X_RA:       219.23 [deg] (J2000)
SC_X_DEC:       17.99 [deg]
SC_Z_RA:       301.64 [deg]
SC_Z_DEC:      -22.13 [deg]
SUN_POSTN:     296.69d {+19h 46m 46s}  -21.17d {-21d 10' 24"}
SUN_DIST:      111.18 [deg]
MOON_POSTN:     37.70d {+02h 30m 48s}   +9.31d {+09d 18' 18"}
MOON_DIST:     100.15 [deg]
PROG_VERSION:  5.33
PROG_LEVEL:    1
COMMENTS:      Definite GRB.  
COMMENTS:      This notice is based on 24 1.024-sec samples of the light curve.

GCN/RXTE_PCA_POSITION

TITLE:           GCN/RXTE_PCA BURST POSITION NOTICE
NOTICE_DATE:     Sun 16 Jan 00 00:43:23 UT
NOTICE_TYPE:     RXTE-PCA
TRIGGER_NUM:     7954
GRB_DATE:        11558 TJD;    15 DOY;   00/01/15
GRB_TIME:        53372.03 SOD {14:49:32.03} UT
GRB_RXTE_RA:     120.80d {+08h 03m 12s} (J2000),
                 120.80d {+08h 03m 12s} (current),
                 120.23d {+08h 00m 56s} (1950)
GRB_RXTE_DEC:    -17.10d {-17d 05' 59"} (J2000),
                 -17.10d {-17d 06' 00"} (current),
                 -16.96d {-16d 57' 30"} (1950)
GRB_RXTE_ERROR:  0.200 [deg radius, statistical only]
GRB_RXTE_INTEN:  2.00 [mCrab]
SUN_POSTN:       296.69d {+19h 46m 46s}  -21.17d {-21d 10' 24"}
SUN_DIST:        141.51 [deg]
MOON_POSTN:       37.70d {+02h 30m 48s}   +9.31d {+09d 18' 18"}
MOON_DIST:        86.23 [deg]
PROG_LEVEL:      3
COMMENTS:        RXTE-PCA GRB Coordinates.  
COMMENTS:        The RXTE-PCA observation started at 00/01/15 17:23:54.00 UT.  
COMMENTS:        A previously unknown source with a flux of 2 mCrab  
COMMENTS:        was detected at 17:44 UT or 2h55m after the  
COMMENTS:        burst trigger.  The estimated 90  
COMMENTS:        region covers +/- 0.15 deg. in RA and   
COMMENTS:        +/- 0.20 deg. in Decl.   
COMMENTS:        Source variability could cause a systematic  
COMMENTS:        error in Decl. Another RXTE scan is planned  
COMMENTS:        to reduce the uncertainty in Decl.  
COMMENTS:        This message may be cited.  
COMMENTS:        (F. Marshall and T. Takeshima)

GCN notice #519
F. E. Marshall (GSFC), T. Takeshima (USRA/GSFC), T. Giblin & R.M. Kippen (UAH/MSFC) report:
RXTE observed GRB 000115 (BATSE Trigger 7954) for a second time on 16 Jan. 2000 from 03:23 to 03:37 UT. Preliminary analysis shows no significant detection of the X-ray afterglow indicating that it is decaying at least as rapidly as t**-1. The best-fit RXTE position (J2000) remains that determined from the first observation (RA = 120.8, Decl. = -17.1). The 90 per cent confidence error box is approximately 0.3 degrees wide in RA and 0.4 degrees wide in Decl. Substantial variability on the time scale of an hour could cause an additional systematic uncertainty in Decl.
GCN notice #520
K. Hurley, T. Cline, S. Barthelmy, and E. Mazets, report:
KONUS-WIND and NEAR (among others) observed GRB000115 (BATSE #7954). Preliminary triangulation gives an annulus centered at RA(2000)=63.092 o, Decl.(2000)=29.512 o, with radius 72.715 +/- 0.015 o (3 sigma). This annulus intersects the RXTE error box (GCN 519) to form an ~21 sq. arcmin. error box, whose corners are at:
```
RA(2000)        Decl.(2000)

8 h 03 m 12.5 s -17 o 18 ' 00"
8 h 03 m 21.2 s -17 o 18 ' 00"
8 h 03 m 48.0 s -17 o 10 ' 42"
8 h 03 m 48.0 s -17 o 07 ' 42"
```
A map may be found at ssl.berkeley.edu/ipn3/000115 and reproduced below.
GCN notice #521
K. Hurley, reports:
The top edge of the RXTE error box at ssl.berkeley.edu/ipn3/000115 (GCN 520) was incorrectly drawn. A revised figure has now been posted. This does not change the IPN/RXTE error box coordinates. Thanks to J. Halpern for pointing out this error.
GCN notice #522
T. Giblin and R. M. Kippen (UAH/MSFC) report on behalf of the BATSE GRB Team:
On 2000 January 15.61773 UT, BATSE was triggered by the bright GRB000115 (Trigger# 7954). The time history of the burst is significantly variable with a series of well-defined pulses over a broad range of intensities. The pulse emission is followed by a soft (<300 keV) and weak emission tail with a decay time of approximately 20 seconds. The measured T50 and T90 durations are 4.5 (+/- 0.09) and 15.0 (+/- 0.14) seconds, respectively.
The brightest peak of the burst and several weaker pulses show emission above 300 keV. The energy fluence hardness ratio (100-300 keV / 50-100 keV) is 3.18 (+/- 0.02), typical for long bursts. The 50-300 keV peak flux measured on the 64 ms timescale is 56.96 (+/- 0.81) photons/s/cm^2, placing it in the top 1% of the BATSE peak flux distribution. The fluence above 25 keV is 4.36 (+/- 0.07) x 10^-5 ergs/cm^2, placing it in the top 10% of the BATSE fluence distribution. The BATSE location is consistent with the x-ray afterglow detected by RXTE/PCA (GCN 519) and with the IPN annulus (GCN 520-521). The BATSE light curve and skymap are now available at: http://gammaray.msfc.nasa.gov/~kippen/batserbr/
GCN notice #524
B. L. Jensen, J. Hjorth, J. Pritchard, H. Pedersen (U. of Copenhagen) N. Masetti, E. Palazzi (ITeSRE-CNR, Bologna) J. Gorosabel (LAEFF-INTA, Madrid) A. J. Castro-Tirado (LAEFF-INTA, Madrid and IAA-CSIC, Granada) M. Salvato (AIP, Potsdam) C. Kouveliotou (USRA, at NASA/MSFC Huntsville) E. Rola, L. Kaper (U. of Amsterdam) M. R. Zapatero-Osorio and A. Rosenberg (IAC, Tenerife) report on behalf of a larger European collaboration:
We have obtained images of the RXTE/IPN error box of GRB 000115 (Marshall et al. GCN #519; Hurley et al. GCN #520), with the CTIO 0.9m telescope, the ESO Danish 1.5m telescope (+DFOSC), the 1.23m CAHA telescope and the 0.82m IAC telescope, in BVR between Jan 17.127 and Jan 21.382, as follows:
```
Telescope, Filter, Exp., Date,                     Seeing, Lim_mag.
===================================================================
1.5DK         R   6x300s (2000 Jan 17.127-17.155 UT), 1.8"  22.3
1.5DK         R   6x300s (2000 Jan 17.329-17.357 UT), 1.7"  22.5

CTIO          R   3x600s (2000 Jan 17.093-17.115 UT), 1.6"  21.5
CTIO          R   3x600s (2000 Jan 17.243-17.265 UT), 1.6"  21.6

1.23-CAHA     B     900s (2000 Jan 17.956-17.967 UT), 2.2"  21.1
1.23-CAHA     R   2x450s (2000 Jan 17.941-17.954 UT), 2.0"  22.5

IAC80         R   4x900s (2000 Jan 18.050-18.083 UT), 2.4"  21.2
IAC80         R   4x900s (2000 Jan 18.096-18.129 UT), 2.4"  21.2

1.23-CAHA     V     600s (2000 Jan 18.065-18.073 UT), 2.2"  22.0
1.23-CAHA     B    1200s (2000 Jan 18.953-18.967 UT), 2.3"  21.4

1.23-CAHA     B    1800s (2000 Jan 19.946-19.967 UT), 3.6"  20.5

1.5DK         R   8x300s (2000 Jan 21.344-21.382 UT), 2.0"  22.0
```
No optical afterglow candidate is evident from analyzing these data, nor from comparison with DSS. We found no object down to R~22.0 (B~20.5) (USNO A2.0-based calibration) to show variation of more than R=0.3 (B=0.3) mag during the period observed.
GCN notice #558
A. Henden (USRA/USNO) reports on behalf of the USNO GRB team:
We have acquired BVRcIc all-sky photometry for the field of GRB000115 with the USNOFS 1.0-m telescope on two photometric nights. This is a single 11x11arcmin field located towards the southeastern corner of the RXTE error box. We have placed the photometric data on our anonymous ftp site: ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb000115.dat. The astrometry in these files is based on linear plate solutions with respect to USNO-A2.0. The internal errors are less than 100mas. As no optical counterpart has been identified, only aperture photometry has been performed and the file does not go as faint as for previous fields.
GCN notice #563
J. Gorosabel (DSRI, Copenhagen, Denmark) F. Vrba, A. Henden (U. S. Naval Observatory, Flagstaff, USA) V. Mohan, A.K. Pandey, R. Sagar, S.B. Pandey (UPSO, Nainital, India) P. Kilmartin (University of Canterbury, New Zealand) I. Bond, N. Rattenbury, P. Yock (University of Auckland, New Zealand) A.J. Castro-Tirado (LAEFF-INTA, Madrid and IAA-CSIC, Granada, Spain) report on behalf of a larger European collaboration:
We have obtained optical images of the RXTE/IPN error box of GRB 000115 (GCN 519, GCN 520) with the UPSO 1.04-m Sampurnanand telescope, the USNO Flagstaff Station 1.0-m telescope and the 0.61-m Mount John University Observatory (MJUO) telescope between Jan 16.275 UT and Jan 19.764 UT.
The observations are summarized in the following table:
```
      Date            Telescope     Seeing(")   Exp.   Filter   Lim. Mag.
------------------------------------------------------------------------
Jan 16.275-16.357     1.00-USNO       2.7       5400      R^      22.1
Jan 17.701-17.765     1.04-UPSO       2.6       4200      I       21.7
Jan 17.906-17.950     0.61-MJUO       3.1       900     (R+I)*    I~20
Jan 18.781-18.899     1.04-UPSO       3.1       3000      I       21.2
Jan 19.697-19.764     1.04-UPSO       2.4       4200      I       22.0
------------------------------------------------------------------------
 ^ The image does not completely cover the RXTE/IPN error box,
   missing the southern part (~20%) of it.

 * Observations performed through a broad-band filter (R + I bandpass).
------------------------------------------------------------------------
```
Photometry of these data does not reveal reliable variable sources in the error box, being any variability less than I=0.25 and R=0.20 mag for objects with I < 21 and R < 21. The USNO R-band co-added image has been compared to the one taken with the 1.54-m Danish telescope on Jan 21.344-21.382 UT (GCN 524). The zero points have been determined based on the standard stars given by A. Henden (GCN 558).

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Jochen Greiner, last update: 18-Feb-2000 [Disclaimer]