| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
1:10:23 UTC |
GCN_circulars,Swift Det |
| ra |
129.9375° |
Swift |
| decl |
-39.2929° |
Swift |
| pos_error |
2.98e-04° |
Swift |
| GBM_located |
False |
|
| mjd |
60829.04887731482 |
GCN_circulars,Swift Det |
| Swift table |
|---|
| GRB_name |
GRB250603A |
| t_trigger |
1:10:23 UTC |
| ra |
129.9375° |
| decl |
-39.2929° |
| pos_error |
2.98e-04° |
| GCN 40613 table |
|---|
| GRB_name |
GRB250603A |
| GCN_number |
40613 |
| Detection_method |
Swift Det |
| t_trigger |
1:10:23 UTC |
| ra |
129.9180° |
| decl |
-39.2680° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 40613
SUBJECT: GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
DATE: 25/06/03 01:51:05 GMT
FROM: David Palmer at LANL
T. M. Parsotan (GSFC), R. Brivio (INAF-OAB), R. Gupta (NASA GSFC),
M. J. Moss (GSFC), D. M. Palmer (LANL) and C. Salvaggio (INAF-OAB)
report on behalf of the Neil Gehrels Swift Observatory Team:
At 01:10:23 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 250603A (trigger=1320335). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 129.918, -39.268 which is
RA(J2000) = 08h 39m 40s
Dec(J2000) = -39d 16' 05"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of about 18 sec with a possible short
spike at T0+16 sec. The peak count rate was ~1,300 counts/sec
(15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 01:12:04.7 UT, 101.7 seconds after
the BAT trigger. No source was detected in the 2.5-s promptly available
image. We are waiting for the full dataset to detect and localise the
XRT counterpart.
Although the initial 2.5s of XRT data do not show a clear X-ray
afterglow, the high significance of the BAT image (7.82 sigma)
gives us confidence that this is an astrophysical source.
Further analysis awaits the full downlinked dataset.
We note the presence of Fermi-GBM event at ~T+10 minutes
(GBM trigger: 770606412) with a position consistent (to its
25d error radius) with this source location.
Given the location of the BAT detection at 1.42d from the Galactic
plane, persistent flux over 10 minutes would suggest a Galactic transient.
If so, we would name it Swift J0839.7-3916 .
Burst Advocate for this burst is T. M. Parsotan (tyler.parsotan AT nasa.gov).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)
|
| GCN 40615 table |
|---|
| GRB_name |
GRB250603A |
| GCN_number |
40615 |
| Detection_method |
Swift-XRT Other |
| ra |
129.9375° |
| decl |
-39.2929° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 40615
SUBJECT: GRB 250603A: Swift-XRT position and confirmation of GRB nature
DATE: 25/06/03 05:40:03 GMT
FROM: K.L. Page at U Leicester
K.L. Page and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT
team:
The XRT began observing the field of GRB 250603A (GCN Circ. 40613) at
01:12:04.7 UT, 101.7 seconds after the BAT trigger. Using
promptly-collected data (although downlinked after a delay), we find a
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
129.93750, -39.29289 which is equivalent to:
RA(J2000) = 08h 39m 45.00s
Dec(J2000) = -39d 17' 34.4"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 104 arcseconds from the BAT onboard position, within the
BAT error circle.
Given the nature of the fading X-ray light-curve, we confirm this trigger
as GRB 250603A, and not a new Galactic transient.
This circular is an official product of the Swift-XRT team.
|
| GCN 40616 table |
|---|
| GRB_name |
GRB250603A |
| GCN_number |
40616 |
| Detection_method |
Swift-XRT Det |
| ra |
129.9375° |
| decl |
-39.2929° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 40616
SUBJECT: GRB 250603A: Enhanced Swift-XRT position
DATE: 25/06/03 06:07:13 GMT
FROM: Phil Evans at U of Leicester
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1415 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 250603A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 129.93745, -39.29287 which is equivalent
to:
RA (J2000): 08h 39m 44.99s
Dec (J2000): -39d 17' 34.3"
with an uncertainty of 2.3 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.
|
| GCN 40618 table |
|---|
| GRB_name |
GRB250603A |
| GCN_number |
40618 |
| Detection_method |
Swift-XRT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 40618
SUBJECT: GRB 250603A: Swift-XRT refined Analysis
DATE: 25/06/03 12:58:34 GMT
FROM: Phil Evans at U of Leicester
S. Campana (INAF-OAB), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB),
D.N. Burrows (PSU), M.A. Williams (PSU), S. Dichiara (PSU), J.P.
Osborne (U. Leicester), K.L. Page (U. Leicester) and P.A. Evans report
on behalf of the Swift-XRT team:
We have analysed 7.3 ks of XRT data for GRB 250603A, from 92 s to 34.7
ks after the trigger. The data comprise 3 s in Windowed Timing (WT)
mode (taken while Swift was slewing), with the remainder in Photon
Counting (PC) mode.
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.17 (+0.09, -0.08).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.48 (+0.32, -0.30). The
best-fitting absorption column is 1.6 (+0.5, -0.4) x 10^22 cm^-2, in
excess of the Galactic value of 6.9 x 10^21 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 7.6 x 10^-11 (1.1 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.6 (+0.5, -0.4) x 10^22 cm^-2
Galactic foreground: 6.9 x 10^21 cm^-2
Excess significance: 3.3 sigma
Photon index: 1.48 (+0.32, -0.30)
If the light curve continues to decay with a power-law decay index of
1.17, the count rate at T+24 hours will be 8.8 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.7 x
10^-14 (9.8 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01320335.
This circular is an official product of the Swift-XRT team.
|
| GCN 40619 table |
|---|
| GRB_name |
GRB250603A |
| GCN_number |
40619 |
| Detection_method |
Swift-UVOT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 40619
SUBJECT: GRB 250603A: Swift/UVOT Upper Limits
DATE: 25/06/03 13:14:52 GMT
FROM: Samantha Oates at University of Birmingham
S. R. Oates (Lancaster U.) and T. M. Parsotan (GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 250603A
105 s after the BAT trigger (Parsotan et al., GCN Circ. 40613).
No optical afterglow consistent with the enhanced XRT position
(Beardmore et al., GCN Circ. 40616) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 105 255 147 >20.4
u_FC 318 567 246 >19.7
white 105 1531 382 >21.0
v 647 5129 190 >19.0
b 573 1516 97 >19.6
u 318 1491 324 >19.8
w1 697 1467 78 >18.7
m2 672 1442 97 >18.5
w2 623 5029 294 >19.2
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.89 in the direction of the burst
(Schlegel et al. 1998).
|