| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
18:03:49 UTC |
GCN_circulars,Swift Det |
| ra |
3.3877° |
Swift |
| decl |
-54.4914° |
Swift |
| pos_error |
1.94e-04° |
Swift |
| T90 |
23.0 s |
Swift |
| T90_start |
18:03:49 UTC |
Swift |
| fluence |
3.30e-07 erg/cm² |
Swift |
| T100 |
23.0 s |
|
| GBM_located |
False |
|
| mjd |
58188.752650462964 |
GCN_circulars,Swift Det |
| IPN table |
|---|
| GRB_name |
GRB180311A |
| ra |
3.4333° |
| decl |
-54.4833° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB180311A |
| t_trigger |
18:03:49 UTC |
| ra |
3.3877° |
| decl |
-54.4914° |
| pos_error |
1.94e-04° |
| T90 |
23.0 s |
| fluence |
3.30e-07 erg/cm² |
| GCN 22468 table |
|---|
| GRB_name |
GRB180311A |
| GCN_number |
22468 |
| Detection_method |
Swift Det |
| t_trigger |
18:03:49 UTC |
| ra |
3.4330° |
| decl |
-54.4790° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 22468
SUBJECT: GRB 180311A: Swift detection of a burst
DATE: 18/03/11 18:18:00 GMT
FROM: David Palmer at LANL
K. L. Page (U Leicester), A. Deich (PSU), S. W. K Emery (UCL-MSSL),
J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL),
M. H. Siegel (PSU) and A. Tohuvavohu (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:
At 18:03:49 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 180311A (trigger=813721). Swift slewed to the burst after
a brief delay to clear the Earth limb observing contraint.
The BAT on-board calculated location is
RA, Dec 3.433, -54.479 which is
RA(J2000) = 00h 13m 44s
Dec(J2000) = -54d 28' 43"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex peak
structure with a duration of about 30 sec. The peak count rate
was ~1000 counts/sec (15-350 keV), at ~4 sec after the trigger.
The XRT began observing the field at 18:08:24.5 UT, 275.3 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 3.39027, -54.49162 which
is equivalent to:
RA(J2000) = 00h 13m 33.66s
Dec(J2000) = -54d 29' 29.8"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 100 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (1.59 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.9
(+3.32/-2.86) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 279 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 26% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.01.
Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk).
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/too.html.)
|
| GCN 22469 table |
|---|
| GRB_name |
GRB180311A |
| GCN_number |
22469 |
| Detection_method |
Swift-XRT Other |
| ra |
3.3872° |
| decl |
-54.4914° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 22469
SUBJECT: GRB 180311A: Prompt enhanced Swift-XRT position
DATE: 18/03/11 19:03:38 GMT
FROM: Phil Evans at U of Leicester
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 180311A, we find an
enhanced XRT position of the afterglow: RA, Dec: 3.3872, -54.4914 which
is equivalent to:
RA (J2000) = 00 13 32.93
Dec (J2000) = -54 29 29.0
with an uncertainty of 2.1 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/813721.
Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
|
| GCN 22470 table |
|---|
| GRB_name |
GRB180311A |
| GCN_number |
22470 |
| Detection_method |
Swift-XRT Det |
| ra |
3.3876° |
| decl |
-54.4915° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 22470
SUBJECT: GRB 180311A: Enhanced Swift-XRT position
DATE: 18/03/11 22:50:21 GMT
FROM: Phil Evans at U of Leicester
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 3908 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 180311A, 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 = 3.38761, -54.49145 which is equivalent
to:
RA (J2000): 00h 13m 33.03s
Dec (J2000): -54d 29' 29.2"
with an uncertainty of 1.7 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 22473 table |
|---|
| GRB_name |
GRB180311A |
| GCN_number |
22473 |
| Detection_method |
Swift-XRT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 22473
SUBJECT: GRB 180311A: Swift-XRT refined Analysis
DATE: 18/03/12 03:53:59 GMT
FROM: Phil Evans at U of Leicester
A. Tohuvavohu (PSU), S. J. LaPorte (PSU), J.A. Kennea (PSU), A.P.
Beardmore (U. Leicester), P.A. Evans (U. Leicester), V. D'Elia (ASDC),
A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB) and K.L. Page report on
behalf of the Swift-XRT team:
We have analysed 8.3 ks of XRT data for GRB 180311A (Page et al. GCN
Circ. 22468), from 284 s to 20.1 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Goad et al. (GCN Circ. 22469).
The light curve can be modelled with an initial power-law decay with an
index of alpha=3.1 (+0.9, -0.6), followed by a break at T+636 s to an
alpha of 0.57 (+0.10, -0.09).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.07 (+0.20, -0.19). The
best-fitting absorption column is 5.5 (+4.3, -3.7) x 10^20 cm^-2, in
excess of the Galactic value of 1.6 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.1 x 10^-11 (3.6 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 5.5 (+4.3, -3.7) x 10^20 cm^-2
Galactic foreground: 1.6 x 10^20 cm^-2
Excess significance: 1.7 sigma
Photon index: 2.07 (+0.20, -0.19)
If the light curve continues to decay with a power-law decay index of
0.57, the count rate at T+24 hours will be 0.012 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.6 x
10^-13 (4.2 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00813721.
This circular is an official product of the Swift-XRT team.
|
| GCN 22474 table |
|---|
| GRB_name |
GRB180311A |
| GCN_number |
22474 |
| Detection_method |
Swift-BAT Det |
| ra |
3.3790° |
| decl |
-54.4910° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 22474
SUBJECT: GRB 180311A, Swift-BAT refined analysis
DATE: 18/03/12 13:00:00 GMT
FROM: Amy Lien at GSFC
M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), K. L. Page (U Leicester),
T. Sakamoto (AGU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180311A (trigger #813721)
(Page et al., GCN Circ. 22468). The BAT ground-calculated position is
RA, Dec = 3.379, -54.491 deg which is
RA(J2000) = 00h 13m 31.0s
Dec(J2000) = -54d 29' 26.6"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 94%.
The mask-weighted light curve shows a single-peaked structure that starts
at ~ T0, peaks at ~T+3 s, and ends at ~T+26 s. T90 (15-350 keV) is
23.0 +- 8.7 sec (estimated error including systematics).
The time-averaged spectrum from T-0.2 to T+26.6 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.78 +- 0.29. The fluence in the 15-150 keV band is 3.3 +- 0.7 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+2.88 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.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/813721/BA/
|
| GCN 22475 table |
|---|
| GRB_name |
GRB180311A |
| GCN_number |
22475 |
| Detection_method |
Swift-UVOT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 22475
SUBJECT: GRB 180311A: Swift/UVOT Upper Limits
DATE: 18/03/12 16:42:41 GMT
FROM: Frank Marshall at Swift/UVOT
F. E. Marshall (NASA/GSFC) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180311A
280 s after the BAT trigger (Page et al., GCN Circ. 22468).
No optical afterglow consistent with the enhanced XRT position
(Goad et al. GCN Circ. 22470)
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 280 430 147 >20.3
white 280 6742 589 >21.2
v 437 7155 333 >19.4
b 536 8600 488 >20.9
u 511 7770 561 >20.5
w1 486 7565 330 >20.2
m2 7160 7360 197 >20.3
w2 1187 6950 255 >20.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).
|