| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
6:12:38 UTC |
GCN_circulars,Swift Det |
| ra |
183.1127° |
Swift |
| decl |
-67.6639° |
Swift |
| pos_error |
4.53e-04° |
Swift |
| T90 |
52.6 s |
Swift |
| T90_start |
6:12:38 UTC |
Swift |
| fluence |
4.90e-07 erg/cm² |
Swift |
| T100 |
52.6 s |
|
| GBM_located |
False |
|
| mjd |
57626.25877314815 |
GCN_circulars,Swift Det |
| IPN table |
|---|
| GRB_name |
GRB160826A |
| ra |
183.0750° |
| decl |
-67.6833° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB160826A |
| t_trigger |
6:12:38 UTC |
| ra |
183.1127° |
| decl |
-67.6639° |
| pos_error |
4.53e-04° |
| T90 |
52.6 s |
| fluence |
4.90e-07 erg/cm² |
| GCN 19866 table |
|---|
| GRB_name |
GRB160826A |
| GCN_number |
19866 |
| Detection_method |
Swift Det |
| t_trigger |
6:12:38 UTC |
| ra |
183.0740° |
| decl |
-67.6890° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 19866
SUBJECT: GRB 160826A: Swift detection of a burst
DATE: 16/08/26 06:29:47 GMT
FROM: Kim Page at U.of Leicester
B. Mingo (U Leicester), H. A. Krimm (CRESST/GSFC/USRA),
K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of
the Swift Team:
At 06:12:38 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 160826A (trigger=709907). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 183.074, -67.689 which is
RA(J2000) = 12h 12m 18s
Dec(J2000) = -67d 41' 19"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a multi-peaked
structure with a duration of about 30 sec. The peak count rate
was ~1300 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 06:14:20.8 UT, 102.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 183.11400,
-67.66411 which is equivalent to:
RA(J2000) = 12h 12m 27.36s
Dec(J2000) = -67d 39' 50.8"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 104 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 consistent with the Galactic value of 4.59
x 10^21 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 5.77e-10 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 108 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. Because of the density of catalogued stars, further
analysis is required to report an upper limit for any afterglow in the
sub-image. The 8'x8' region for the list of sources generated on-board covers
100% of the XRT error circle. Because of the density of catalogued stars,
further analysis is required to report an upper limit for any afterglow in the
region. No correction has been made for the expected extinction corresponding
to E(B-V) of 0.47.
Burst Advocate for this burst is B. Mingo (bm188 AT 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 19868 table |
|---|
| GRB_name |
GRB160826A |
| GCN_number |
19868 |
| Detection_method |
Swift-XRT Other |
| ra |
183.1127° |
| decl |
-67.6639° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 19868
SUBJECT: GRB 160826A: Swift-XRT refined Analysis
DATE: 16/08/26 15:36:20 GMT
FROM: Phil Evans at U of Leicester
P.A. Evans (U. Leicester), A. D'Ai (INAF-IASFPA), A. Maselli
(INAF-IASFPA), A. Melandri (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU), D.N. Burrows (PSU), S.L. Gibson (U. Leicester), J.P.
Osborne (U. Leicester) and B. Mingo report on behalf of the Swift-XRT
team:
We have analysed 6.5 ks of XRT data for GRB 160826A (Mingo et al. GCN
Circ. 19866), from 93 s to 22.1 ks after the BAT trigger. The data
comprise 114 s in Windowed Timing (WT) mode (the first 5 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The refined XRT position is RA, Dec = 183.1127, -67.6639 which is
equivalent to:
RA (J2000): 12 12 27.05
Dec(J2000): -67 39 50.0
with an uncertainty of 3.5 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.64 (+0.06, -0.05).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.68 (+0.31, -0.28). The
best-fitting absorption column is 9.1 (+3.3, -2.7) x 10^21 cm^-2, in
excess of the Galactic value of 4.6 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 5.7 x 10^-11 (8.5 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 9.1 (+3.3, -2.7) x 10^21 cm^-2
Galactic foreground: 4.6 x 10^21 cm^-2
Excess significance: 2.7 sigma
Photon index: 1.68 (+0.31, -0.28)
If the light curve continues to decay with a power-law decay index of
1.64, the count rate at T+24 hours will be 2.1 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x
10^-14 (1.7 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/00709907.
This circular is an official product of the Swift-XRT team.
|
| GCN 19871 table |
|---|
| GRB_name |
GRB160826A |
| GCN_number |
19871 |
| Detection_method |
Swift-UVOT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 19871
SUBJECT: GRB 160826A: Swift/UVOT Upper Limits
DATE: 16/08/26 19:00:50 GMT
FROM: Mike Siegel at PSU/Swift MOC
S. J. LaPorte (PSU) and B. Mingo (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160826A
109 s after the BAT trigger (Mingo et al., GCN Circ. 19866).
No optical afterglow consistent with the XRT position
(Mingo et al. GCN Circ. 19868)
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 109 259 147 >21.1
u_FC 267 517 246 >19.8
white 109 1195 353 >22.1
v 597 1245 78 >19.8
b 523 1170 58 >20.2
u 267 4893 340 >19.8
w1 648 1290 74 >19.0
m2 622 1269 78 >19.3
w2 573 1220 78 >19.9
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.47 in the direction of the burst
(Schlegel et al. 1998).
|
| GCN 19872 table |
|---|
| GRB_name |
GRB160826A |
| GCN_number |
19872 |
| Detection_method |
Swift-BAT Det |
| ra |
183.1200° |
| decl |
-67.6640° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 19872
SUBJECT: GRB 160826A: Swift-BAT refined analysis
DATE: 16/08/26 19:35:43 GMT
FROM: Hans Krimm at NASA-GSFC
M. Stamatikos (OSU), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), B. Mingo (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (AGU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 160826A (trigger #709907)
(Mingo, et al., GCN Circ. 19866). The BAT ground-calculated position is
RA, Dec = 183.120, -67.664 deg which is
RA(J2000) = 12h 12m 28.8s
Dec(J2000) = -67d 39' 51.7"
with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted light curve shows a single, rough FRED-like peak starting
at T+0 sec, peaking at about T+5 sec and decaying to near background by T+20
sec. This is followed by low-level emission out to about T+70 sec.
T90 (15-350 keV) is 52.6 +- 14.5 sec (estimated error including systematics).
The time-averaged spectrum from T+3.85 to T+61.58 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.54 +- 0.29. The fluence in the 15-150 keV band is 4.9 +- 0.9 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+4.64 sec in the 15-150 keV band
is 0.4 +- 0.1 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/709907/BA/
|