| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
5:15:11 UTC |
GCN_circulars,Swift Det |
| ra |
291.7916° |
Swift |
| decl |
-65.3936° |
Swift |
| pos_error |
2.33e-04° |
Swift |
| T90 |
6.26 s |
Swift |
| T90_start |
5:15:11 UTC |
Swift |
| fluence |
2.70e-07 erg/cm² |
Swift |
| T100 |
6.26 s |
|
| GBM_located |
False |
|
| mjd |
56927.218877314815 |
GCN_circulars,Swift Det |
| IPN table |
|---|
| GRB_name |
GRB140927A |
| ra |
291.8458° |
| decl |
-65.3833° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB140927A |
| t_trigger |
5:15:11 UTC |
| ra |
291.7916° |
| decl |
-65.3936° |
| pos_error |
2.33e-04° |
| T90 |
6.26 s |
| fluence |
2.70e-07 erg/cm² |
| GCN 16842 table |
|---|
| GRB_name |
GRB140927A |
| GCN_number |
16842 |
| Detection_method |
Swift Det |
| t_trigger |
5:15:11 UTC |
| ra |
291.8450° |
| decl |
-65.3880° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16842
SUBJECT: GRB 140927A: Swift detection of a burst
DATE: 14/09/27 05:35:42 GMT
FROM: David Palmer at LANL
R. L. C. Starling (U Leicester), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (NASA/GSFC), C. J. Mountford (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU) and
T. N. Ukwatta (LANL) report on behalf of the Swift Team:
At 05:15:11 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 140927A (trigger=613775). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 291.845, -65.388 which is
RA(J2000) = 19h 27m 23s
Dec(J2000) = -65d 23' 14"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a spiky
structure with a duration of about 30 sec. The peak count rate
was ~1500 counts/sec (15-350 keV), at ~6 sec after the trigger.
The XRT began observing the field at 05:17:13.7 UT, 122.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 291.79216, -65.39285 which is
equivalent to:
RA(J2000) = 19h 27m 10.12s
Dec(J2000) = -65d 23' 34.3"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 81 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 (7.56 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4
(+3.21/-2.72) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 250 seconds with the U filter starting
123 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 100% of the
XRT error circle. The typical 3-sigma upper limit has been about 19.2 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 18.0 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.08.
Burst Advocate for this burst is R. L. C. Starling (rlcs1 AT star.le.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 16843 table |
|---|
| GRB_name |
GRB140927A |
| GCN_number |
16843 |
| Detection_method |
Swift-XRT Det |
| ra |
291.7916° |
| decl |
-65.3936° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16843
SUBJECT: GRB 140927A: Enhanced Swift-XRT position
DATE: 14/09/27 15:09:54 GMT
FROM: Phil Evans at U of Leicester
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 2980 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 140927A, 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 = 291.79158, -65.39357 which is equivalent
to:
RA (J2000): 19h 27m 9.98s
Dec (J2000): -65d 23' 36.9"
with an uncertainty of 1.8 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 16844 table |
|---|
| GRB_name |
GRB140927A |
| GCN_number |
16844 |
| Detection_method |
Swift-XRT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16844
SUBJECT: GRB 140927A: Swift-XRT refined Analysis
DATE: 14/09/27 17:35:04 GMT
FROM: Phil Evans at U of Leicester
J.A. Kennea (PSU), V. Mangano (PSU), M.C. Stroh (PSU), A.P. Beardmore
(U. Leicester), P.A. Evans (U. Leicester), B.P. Gompertz (U.
Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), M. de Pasquale
(INAF-IASFPA) and R.L.C. Starling report on behalf of the Swift-XRT
team:
We have analysed 7.1 ks of XRT data for GRB 140927A (Starling et al.
GCN Circ. 16842), from 108 s to 29.7 ks after the BAT trigger. The
data comprise 7 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Evans et al. (GCN Circ.
16843).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.76 (+/-0.05).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.79 (+0.25, -0.23). The
best-fitting absorption column is 1.6 (+1.0, -0.8) x 10^21 cm^-2, in
excess of the Galactic value of 7.6 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 3.9 x 10^-11 (4.8 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.6 (+1.0, -0.8) x 10^21 cm^-2
Galactic foreground: 7.6 x 10^20 cm^-2
Excess significance: 1.7 sigma
Photon index: 1.79 (+0.25, -0.23)
If the light curve continues to decay with a power-law decay index of
0.76, the count rate at T+24 hours will be 4.7 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x
10^-13 (2.3 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/00613775.
This circular is an official product of the Swift-XRT team.
|
| GCN 16845 table |
|---|
| GRB_name |
GRB140927A |
| GCN_number |
16845 |
| Detection_method |
Swift-BAT Det |
| ra |
291.8020° |
| decl |
-65.4000° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16845
SUBJECT: GRB 140927A: Swift-BAT refined analysis
DATE: 14/09/27 21:49:44 GMT
FROM: Amy Lien at GSFC
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), R. L. C. Starling (U Leicester)
J. Tueller (GSFC), 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 140927A (trigger #613775)
(Starling, et al., GCN Circ. 16842). The BAT ground-calculated position is
RA, Dec = 291.802, -65.400 deg which is
RA(J2000) = 19h 27m 12.5s
Dec(J2000) = -65d 23' 58.4"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 54%.
The mask-weighted light curve shows a multi-peaked structure starts at ~ T0 and
ends at ~ T+9 s. The structure has roughly two main peaks, at ~ T+3.8 s and ~ T+7.7 s,
respectively. T90 (15-350 keV) is 6.26 +- 1.43 sec (estimated error including systematics).
The time-averaged spectrum from T+0.43 to T+8.70 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.82 +- 0.30. The fluence in the 15-150 keV band is 2.7 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+7.70 sec in the 15-150 keV band
is 0.9 +- 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/613775/BA/
|
| GCN 16846 table |
|---|
| GRB_name |
GRB140927A |
| GCN_number |
16846 |
| Detection_method |
Swift-UVOT Other |
| ra |
291.7924° |
| decl |
-65.3932° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 16846
SUBJECT: GRB 140927A: Swift-UVOT analysis
DATE: 14/09/27 22:34:48 GMT
FROM: Craig Swenson at PSU/Swift
C. Swenson (PSU) and R. L. C. Starling (U Leicester) report on
behalf of the Swift UVOT team:
Analysis of the field of GRB 140927A shows a bright DSS source
located at RA, DEC= 291.79237,-65.39323, which is 1.7" from the
enhanced XRT position (Evans et al., GCN Circ. 16843). No elongation
or fading of the known source is observed in the first 10e4 seconds
of UVOT observations, meaning that any potential afterglow contribution
is being overpowered by the known source.
|