Gamma-ray Burst 060203

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Fri 03 Feb 06 23:58:26 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     180151,   Seg_Num: 0
GRB_RA:          103.514d {+06h 54m 03s} (J2000),
                 103.692d {+06h 54m 46s} (current),
                 102.045d {+06h 48m 11s} (1950)
GRB_DEC:         +71.823d {+71d 49' 25"} (J2000),
                 +71.816d {+71d 48' 56"} (current),
                 +71.885d {+71d 53' 06"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=1566 [image_cnts]
TRIGGER_DUR:     80.000 [sec] 
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        -0.99 SOD {00:00:00.-98} UT
BKG_DUR:         0 [sec]
GRB_DATE:        13769 TJD;    34 DOY;   06/02/03
GRB_TIME:        86135.00 SOD {23:55:35.00} UT
GRB_PHI:         -168.01 [deg]
GRB_THETA:        43.13 [deg]
SOLN_STATUS:     0x413
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    8.16 [sigma]
MERIT_PARAMS:     +1  +0  +0  +6  +1  -2  +0  +0 +51  +1 
SUN_POSTN:       317.49d {+21h 09m 57s}  -16.33d {-16d 19' 44"}
SUN_DIST:        121.06 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:       26.30d {+01h 45m 11s}  +12.92d {+12d 55' 08"}
MOON_DIST:        73.81 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      143.22, 25.87 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       96.34, 48.68 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This Notice was delayed by more than 90 sec; probably due to it occurring during a Malindi downlink session.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 16.87,12.04 [deg].  
COMMENTS:        This trigger occured while the StarTracker had lost lock, so it is probably bogus.

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 04 Feb 06 00:00:20 UT
NOTICE_TYPE:     Swift-BAT GRB Lightcurve
TRIGGER_NUM:     180151,   Seg_Num: 0
GRB_RA:          103.514d {+06h 54m 03s} (J2000),
                 103.692d {+06h 54m 46s} (current),
                 102.045d {+06h 48m 11s} (1950)
GRB_DEC:         +71.823d {+71d 49' 25"} (J2000),
                 +71.816d {+71d 48' 56"} (current),
                 +71.885d {+71d 53' 06"} (1950)
GRB_DATE:        13769 TJD;    34 DOY;   06/02/03
GRB_TIME:        86135.00 SOD {23:55:35.00} UT
TRIGGER_INDEX:   20000
GRB_PHI:         -168.01 [deg]
GRB_THETA:        43.13 [deg]
DELTA_TIME:      0.00 [sec]
TRIGGER_DUR:     80.000 [sec] 
LC_URL:          sw00180151000msb.lc
SUN_POSTN:       317.49d {+21h 09m 57s}  -16.33d {-16d 19' 43"}
SUN_DIST:        121.06 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:       26.31d {+01h 45m 15s}  +12.93d {+12d 55' 36"}
MOON_DIST:        73.80 [deg]
MOON_ILLUM:      36 [%]
GAL_COORDS:      143.22, 25.87 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       96.34, 48.68 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Lightcurve.  
COMMENTS:           
COMMENTS:        The next comments were copied from the BAT_POS Notice:  
COMMENTS:        This is an image trigger.  
COMMENTS:        A point_source was found.  
COMMENTS:        This does not match any source in the on-board catalog.  
COMMENTS:        This does not match any source in the ground catalog.  
COMMENTS:        This is a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 16.87,12.04 [deg].  
COMMENTS:        This trigger occured while the StarTracker had lost lock, so it is probably bogus.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 04 Feb 06 00:45:34 UT
NOTICE_TYPE:     Swift-XRT Nack-Position
TRIGGER_NUM:     180151,   Seg_Num: 0
POINT_RA:        103.557d {+06h 54m 14s} (J2000)
POINT_DEC:       +71.819d {+71d 49' 08"} (J2000)
IMG_START_DATE:  13770 TJD;    35 DOY;   06/02/04
IMG_START_TIME:  2725.85 SOD {00:45:25.85} UT,   2990.9 [sec] since BAT Trigger
+Time
COUNTS:          6    Min_needed= 20
STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
PH2_ITER:        1    Max_iter_allowed= 4
ERROR_CODE:      1
COMMENTS:        SWIFT-XRT Nack Position.
COMMENTS:        No source found in the image.

GCN Circular #4641
A. Retter (PSU), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), N. Gehrels (GSFC), S. Hunsberger (PSU), J. Kennea (PSU), H. Krimm (GSFC/USRA) on behalf of the Swift team: At 23:55:35 UT, Swift-BAT had an 80-sec image trigger. And because of an observing constraint, the spacecraft did not slew to the flight-derived location; and so there are no immediate XRT or UVOT data products to analyze. We note that the star tracker was not in lock at the time of the trigger. Past experience shows that the gyros are able to maintain sufficient tracking to prevent drift and therefore false triggers, but it is still possible that this current trigger is a false positive. We will get the full data set in about 2 hours and may be able to determine the validity of this trigger at that time.

GCN/BACODINE POSITION NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 04 Feb 06 00:50:26 UT
NOTICE_TYPE:     Swift-UVOT Source List
TRIGGER_NUM:     180151,   Seg_Num: 0
POINT_RA:        103.557d {+06h 54m 14s} (J2000)
POINT_DEC:       +71.819d {+71d 49' 08"} (J2000)
POINT_ROLL:      321.295d
IMG_START_DATE:  13770 TJD;    35 DOY;   06/02/04
IMG_START_TIME:  2726.07 SOD {00:45:26.07} UT,   2991.1 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.514
N_STARS:         41
X_OFFSET:        527 [pixels]
Y_OFFSET:        485 [pixels]
X_MAX:           1486 [pixels]
Y_MAX:           1444 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00180151000msufc2991.fits
SUN_POSTN:       317.52d {+21h 10m 05s}  -16.32d {-16d 19' 05"}
SUN_DIST:        121.06 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:       26.76d {+01h 47m 02s}  +13.14d {+13d 08' 10"}
MOON_DIST:        73.48 [deg]
MOON_ILLUM:      37 [%]
GAL_COORDS:      143.22, 25.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       96.36, 48.68 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Source List.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 04 Feb 06 00:51:31 UT
NOTICE_TYPE:     Swift-UVOT Processed Source List
TRIGGER_NUM:     180151,   Seg_Num: 0
POINT_RA:        103.557d {+06h 54m 14s} (J2000)
POINT_DEC:       +71.819d {+71d 49' 08"} (J2000)
POINT_ROLL:      321.295d
IMG_START_DATE:  13770 TJD;    35 DOY;   06/02/04
IMG_START_TIME:  2726.07 SOD {00:45:26.07} UT,   2991.1 [sec] since BAT Trigger Time
FILTER:          3, V
BKG_MEAN:        1.514
N_STARS:         41
X_OFFSET:        527 [pixels]
Y_OFFSET:        485 [pixels]
X_MAX:           1486 [pixels]
Y_MAX:           1444 [pixels]
DET_THRESH:      10
PHOTO_THRESH:    5
SL_URL:          sw00180151000msufc2991.fits
SUN_POSTN:       317.52d {+21h 10m 06s}  -16.32d {-16d 19' 04"}
SUN_DIST:        121.06 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:       26.77d {+01h 47m 05s}  +13.14d {+13d 08' 26"}
MOON_DIST:        73.47 [deg]
MOON_ILLUM:      37 [%]
GAL_COORDS:      143.22, 25.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       96.36, 48.68 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Source List.
COMMENTS:        If you have elected to receive attachments:
COMMENTS:        The uvot_catalog_srclist.fits.gz file does not exist; skipping the attachment.

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 04 Feb 06 00:51:48 UT
NOTICE_TYPE:     Swift-UVOT Image
TRIGGER_NUM:     180151,   Seg_Num: 0
POINT_RA:        103.557d {+06h 54m 14s} (J2000)
POINT_DEC:       +71.819d {+71d 49' 08"} (J2000)
ROLL:            321.295d
IMG_START_DATE:  13770 TJD;    35 DOY;   06/02/04
IMG_START_TIME:  2726.07 SOD {00:45:26.07} UT,   2991.1 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     160706727
X_OFFSET:        847 [pixels]
Y_OFFSET:        805 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1007
Y_GRB_POS:       965
BINNING_INDEX:   1
IM_URL:          sw00180151000msuni2991.fits
SUN_POSTN:       317.52d {+21h 10m 06s}  -16.32d {-16d 19' 04"}
SUN_DIST:        121.06 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:       26.77d {+01h 47m 05s}  +13.14d {+13d 08' 30"}
MOON_DIST:        73.47 [deg]
MOON_ILLUM:      37 [%]
GAL_COORDS:      143.22, 25.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       96.36, 48.68 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Sat 04 Feb 06 00:53:14 UT
NOTICE_TYPE:     Swift-UVOT Processed Image
TRIGGER_NUM:     180151,   Seg_Num: 0
POINT_RA:        103.557d {+06h 54m 14s} (J2000)
POINT_DEC:       +71.819d {+71d 49' 08"} (J2000)
ROLL:            321.295d
IMG_START_DATE:  13770 TJD;    35 DOY;   06/02/04
IMG_START_TIME:  2726.07 SOD {00:45:26.07} UT,   2991.1 [sec] since BAT Trigger Time
FILTER:          3, V
EXPOSURE_ID:     160706727
X_OFFSET:        847 [pixels]
Y_OFFSET:        805 [pixels]
WIDTH:           160 [pixels]
HEIGHT:          160 [pixels]
X_GRB_POS:       1007
Y_GRB_POS:       965
BINNING_INDEX:   1
IM_URL:          sw00180151000msuni2991.fits
SUN_POSTN:       317.52d {+21h 10m 06s}  -16.32d {-16d 19' 03"}
SUN_DIST:        121.06 [deg]   Sun_angle= -9.7 [hr] (East of Sun)
MOON_POSTN:       26.79d {+01h 47m 08s}  +13.15d {+13d 08' 52"}
MOON_DIST:        73.46 [deg]
MOON_ILLUM:      37 [%]
GAL_COORDS:      143.22, 25.89 [deg] galactic lon,lat of the pointing direction
ECL_COORDS:       96.36, 48.68 [deg] ecliptic lon,lat of the pointing direction
COMMENTS:        SWIFT-UVOT Processed Image.  
COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
COMMENTS:        The image has 2x2 binning (compression).  
COMMENTS:        If you have elected to receive attachments:  
COMMENTS:        The uvot_catalog_image.fits.gz file does not exist; skipping the attachment.

GCN Circular #4643
S. Piranomonte (INAF/OAR), D. Malesani (SISSA), A. Pizzella, J. Mendez-Abreu, L. Lessio (INAF/OAPd), I. Yegorova (SISSA), and N. Masetti (INAF/IASF Bo) report on behalf of a larger collaboration:
We observed the field of the possible GRB 060203 (Swift trigger 180151; Retter et al., GCN 4641) using the 182 cm Copernico telescope located in Asiago (Italy), equipped with the AFOSC camera. Our images were taken in the R filter, under moderate conditions (seeing 1.8 arcsec, thin cirrus).
Coaddition of three exposures lasting 10 minutes each one (mean time Feb 4.067 UT, 1.6 h after the trigger) reveals no new sources with respect to the DSS 2, which reaches a comparable depth.
This message can be cited.
GCN Circular #4644
The Swift satellite slewed at 00:45:26 UT on 4 Feb 2006 to the position of the BAT trigger 180151 (Retter et al. 2006, GCN 4641), 2990 s after the trigger. Although it is still not clear whether this trigger is from a real astrophysical source, we find a faint, possibly fading, and uncataloged X-ray source at the following position:
```
RA(J2000) = 6h 54m 3.9s
Dec(J2000) = +71d 48' 39"
```
The estimated uncertainty is 6 arcseconds. The exposure time was 2.5 ks. This source is 44 arcseconds from the reported BAT position for trigger 180151.
This position includes the new XRT boresight, but was processed using proprietary software in an effort to distribute the position as soon as possible. A more definitive statement of the nature of this source will be distributed following analysis of the XRT data processed through the normal XRT pipeline software at the SDC.
GCN Circular #4645
D. Malesani (SISSA) and S. Piranomonte (INAF/OAR) report on behalf of a larger collaboration:
After the report of the position of the possible X-ray counterpart (Burrows, GCN 4644) of the Swift trigger 180151 (Retter et al., GCN 4641), we inspected again our images taken at Asiago (Piranomonte et al., GCN 4643).
Inside the XRT error circle we find a single object at the coordinates (J2000):
```
  alpha = 06:54:03.85;
  delta = +71:48:38.4.
```
The error is estimated to be less than 0.5".
The magnitude of this object is R ~ 20.4 after assuming R=18.1 for the closeby USNO star U1575_02633321 located 15 arcsec N-W.
We have no possibility yet to assess variability. Further observations are in progress.
This message can be cited.
GCN Circular #4646
S. B. Cenko, E. Ofek, A. M. Soderberg (Caltech), N. Cucchiara, D. B. Fox (Penn State) report on behalf of a larger collaboration:
We have imaged the error circle of the possible Swift GRB060203 (Retter et al., GCN 4641) with the automated Palomar 60-inch telescope. Observations consisted of 5 x 150 images in the Kron R filter, taken at a mean epoch of approximately 03:38 UT February 4th.
Inside the XRT error circle, we find the afterglow candidate proposed by Malesani et al. (GCN 4645). Furthermore, we find that since the observations described in Piranomonte et al. (GCN 4643), the object has faded. The approximate magnitude in our images, calibrated with respect to the USNOB-2 catalog, is 21.3 +/- 0.3. We therefore conclude this source is the optical afterglow of GRB060203.
GCN Circular #4647
T.P. McIntyre, S.P. Fuller, K.V. Garimella, A.L. Homewood, D.H. Hartmann (Clemson University), M.A.Leake (Valdosta State University), on behalf of the Clemson GRB Follow-Up Team, report:
We observed the Swift location box (Retter et al, GCN 4641) of GRB060203 with the SARA 0.9-m at Kitt Peak. We co-added 5 R-Band exposures of 300 seconds each, for a total integrated exposure time of 25 minutes, beginning about two hours after the burst at UT02:02:07. At the position given in GCN 4644 (Burrows) of the faint, possibly fading, and uncataloged X-ray source:
```
 RA(J2000) = 6h 54m 3.9s
 Dec(J2000) = +71d 48' 39"
```
we detect no new sources to a limiting magnitude of R ~ 19.2 mag compared to the USNOA2.0 catalogue. Additionally, to the same limiting magnitude, we find no new source across the complete original Swift error box of a three arc-minute radius about:
```
 RA(J2000) = 06h 54m 03s
 Dec(J2000) = +71d 49' 25"
```
Observations/analysis ongoing.
The Clemson Unversity GRB Response SIte may be found at: http://people.clemson.edu/~kgarime/burst/index.php The SARA Homepage may be found at: http://www.saraobservatory.org
This message may be cited.
GCN Circular #4648
J. S. Bloom, K. Alatalo (UCB) and C. Blake (Harvard) report:
"Starting at 2006-Feb-04 01h41m09 UT we began observing the field of =20 GRB 060203 (GCN 4641) with PAIRITEL. We analyzed the mosaics =20 constructed from the first 918 seconds. Consistent with the XRT =20 position (GCN 4644, 4641) and the suggested OT (GCN 4643, 4645, =20 4646), we find a bright IR counterpart in JHKs with preliminary =20 magnitude:
J =3D 17.90 =B1 0.05 H =3D 17.20 =B1 0.06 Ks =3D 16.18 =B1 0.07
Observations continue."
This message may be cited.
```
*****************************************************
Joshua Bloom
Assistant Professor, UC Berkeley
601 Campbell Hall, Berkeley, CA 94720
(510) 643-3839 http://astro.berkeley.edu/~jbloom 
*****************************************************
```
GCN Circular #4649
J. Cummings (GSFC/NRC), L. Barbier (GSFC), S. Barthelmy (GSFC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (GSFC/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) on behalf of the Swift-BAT team:
Using the partial data set from T-60.0 to T+123.1 sec from the recent telemetry downlink, we report further analysis of BAT GRB 060203 (trigger #180151) (Retter, et al., GCN 4641). The BAT ground-calculated position is RA,Dec = 103.468,+71.841 deg {06h 53m 52s,+71d 50' 28"} (J2000) +- 2.8 arcmin, (radius, sys+stat, 90% containment). This is 2 arcmin from the ground-calculated XRT position in Circ 4644. The partial coding was 50%.
The burst has a single broad shallow peak starting at T-20 to T+65 sec. We are waiting for more data to be downlinked and may find that this burst lasts longer than our current estimate. T90 (15-350 keV) is (83 +- 5) sec (estimated error including systematics).
We note that our initial doubts about the reality of this burst have significantly diminished after analyzing the Malindi data set, but these doubts have not been completely eliminated. There is still a small possibility that this trigger is a hard x-ray transient, and not a GRB. It is, however, not at all related to a phantom trigger due to the star tracker problem.
GCN Circular #4650
S. D. Hunsberger (PSU), F. Marshall (GSFC), P. Boyd (GSFC), P. Brown (PSU), and A. Cucchiara (PSU) on behalf of the Swift UVOT team:
UVOT took its first exposure of GRB060203 (Retter et al. GCN 4641) starting at 00:45:26 UT February 4th, approximately 2991 seconds after the trigger. No source is seen in the 197 second exposure with the V filter at the position of the reported optical afterglow (Malesani et al. GCN 4645; Cenko et al. GCN 4646) with a 3-sigma upper limit of 19.3 mag.
GCN Circular #4651
D. Morris (PSU), D. Burrows (PSU), N. Gehrels (GSFC), P. Boyd=20 (GSFC-UMBC), W. Voges (MPE) report on behalf of the Swift XRT team:
We have analyzed the Swift XRT data from the first two orbits of GRB=20 060203 (Retter et al., GCN4641), with a total exposure of 5000 seconds.=20 The refined XRT position is:
```
RA(J2000) = 06h 54m 04.35s
Dec(J2000) = +71d 48' 38.4"
```
This position is 44.6 arcseconds from the BAT position, 2.5 arcseconds=20 from the XRT position given in GCN4644 and 2.4 arcseconds from the=20 optical counterpart position given in GCN4645 (Malesani et al). We=20 estimate an uncertainty of 4 arcseconds radius (90% containment).
The 0.2-10 keV light curve in Photon Counting (PC) mode starts 3100=20 seconds from the BAT trigger (T0). The lightcurve shows evidence of a=20 shallow decay index of 0.6.
A preliminary spectral fit to the PC data gives a spectral power law=20 photon index of 2.24 =B1 0.3 in the 0.2-10 keV band with NH of 1.9e21 =B1= =20 7e20, above the galactic NH value for this direction of 6e20. The=20 unabsorbed 0.2-10 keV flux at the start of the XRT observation is=20 estimated to be about 1E-11 erg/cm2/s. If the current decay slope=20 continues, we predict an unabsorbed 0.2-10 keV flux of about 1e-12=20 erg/cm2/s at T+24hrs.
GCN Circular #4652
I. Bikmaev, A.Galeev, N. Sakhibullin (KSU/AST) I. Khamitov, Z. Aslan (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.), R. Burenin, M. Pavlinsky, R. Sunyaev (IKI)
report:
The field of XRT position of GRB 060203 (Swift BAT Trigger 180151, Retter et al., GCN 4641, GCN 4644) was observed with Russian-Turkish 1.5-m telescope (RTT150, Bakyrlytepe, TUBITAK National Observatory, Turkey) by using Andor CCD.
We made series of 30 sec exposures in Rc and V filters, and series of 60 sec exposures in B-filter on February 04, 00:20 - 03:50 UT.
We confirm the presence of the fading optical transient found by Malesani et al. (GCN 4645) and Genko et al. (GCN 4646) and estimate its magnitudes (relative to R = 18.1, V = 18.7, and B = 19.6 of nearby USNO star U1575_02633321) on our co-added frames as follows:
```
Rc = 19.9 +-0.1  UT(mean) = 00:49  ( 54 min after the burst)
V  = 22.3 +-0.3  UT(mean) = 01:33  ( 98 min   )
B  > 23          UT(mean) = 02:07  ( 2h 12 min)
Rc = 21.0 +-0.1  UT(mean) = 02:49  ( 2h 54 min)
V  > 22.5        UT(mean) = 03:05  ( 3h 10 min)
```
By using our and published R magnitudes the estimated power law decay slope is -0.90+/-0.04 (http://www.tug.tubitak.gov.tr/~irekk/grb/grb060203/grb060203.jpg)
The red spectrum of OT is supporting also by IR data of Bloom et al. (GCN 4648).
This message may be cited.
GCN Circular #4656
H. Krimm (GSFC/USRA), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cannizzo (GSFC-UMBC), J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (GSFC/UMD), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Tashiro (Saitama U.), J. Tueller (GSFC) on behalf of the Swift-BAT team:
Using the data set from T-299.0 to T+183.0 sec from the recent telemetry downlink, we report further analysis of BAT GRB 060203 (trigger #180151) (Retter et al., 4641, Burrows et al., GCN 4644, Cummings et al., GCN 4649). The BAT ground-calculated position is (RA,Dec) = 103.502, 71.838 deg {06h 54m 0.5s,+71d 50' 15.9"} (J2000) +- 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 50%.
Based on the event data that we have, the mask-weighted light curve shows a single broad peak lasting from T-20 to T+65 seconds. T90 (15-350 keV) is 60 +- 10 sec (estimated error including systematics). There is no evidence in the rate data for emission after this peak. We note that according to the flight log files, event data was cut off at T+183 seconds due to a pre-planned slew.
The time-averaged spectrum from T-22.1 to T+45.7 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.62 +- 0.23. The fluence in the 15-150 keV band is (8.5 +- 1.2) x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+25.92 sec in the 15-150 keV band is (0.6 +- 0.2) ph/cm2/sec. All the quoted errors are at the 90% confidence level.
GCN Circular #4680
E. Rol (U. of Leicester), A. Levan (U. of Hertsfordshire), K. Wiersema (U. of Amsterdam), P. Dobbie, D. Boyce (U. of Leicester), N. Tanvir (U. of Hertsfordshire) report on behalf of a larger collabration:
We have observed the optical counterpart of GRB060203 (Malesani, GCN 4645) with the Auxiliary Port Imaging Camera on the William Herschel Telescope. We obtained two epochs of observations in Z-band. Our results of seeing-matched aperture photometry are tabulated below:
```
time since burst  exposure time    seeing    magnitude
    (hours)          (seconds)     (arcsec)

       4.0           5 x 240         0.8       19.75
      22.8           5 x 240         0.7       21.60
```
The statistical error on the magnitude is typically 0.01, while we estimate the zeropoint calibration error to be 0.3 magnitudes.
We thus measure a decay for the optical counterpart of 1.85 +/- 0.01 magnitude over 18.8 hours, with an average decay index of 0.98 +/- 0.01.
GCN Circular #4714
P. Schady (PSU/UCL-MSSL), A. Retter (PSU), P. Brown (PSU), D. Vanden. Berk (PSU), F. Marshall (GSFC), N. Gehrels (GSFC) on behalf of the Swift/UVOT team report:
The Swift/UVOT began taking data on the field of GRB 060203 at 00:45:26 UT on 2006-02-04, approximately 50mins after the BAT trigger (Retter et al., GCN 4641). No afterglow candidate is detected in the summed images of any filter, either within the refined XRT error circle (Morris et al., GCN 4651) or at the position reported by Malesani et al. (GCN 4645) down to the following 3-sigma magnitude upper limits:
```
Filter  T_range(s)  Exp(s)  3sigUL(mag)
V       2976-27952    2618     20.7
B       5392-46016    4005     21.9
U       9808-51808    2952     21.4
UVW1    9600-51072    2516     20.7
UVM2    9392-50160    2829     21.0
UVW2    8976-34464    3816     21.4
White	8784-40240    3121     21.9
```
These magnitudes are uncorrected for Galactic extinction; E(B-V) = 0.158.

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Jochen Greiner, last update: 08-Feb-2006 [Disclaimer]