| Summary table |
|---|
| Variable |
Value |
Source |
| GRB_name_Fermi |
GRB170912273 |
|
| T0 |
6:33:46 UTC |
GCN_circulars,Swift Det |
| ra |
215.4585° |
Swift |
| decl |
-61.9969° |
Swift |
| pos_error |
1.81e-04° |
Swift |
| T90 |
13.568 s |
Fermi_GBM |
| T90_error |
1.557 s |
Fermi_GBM |
| T90_start |
6:33:46.914 UTC |
Fermi_GBM |
| fluence |
3.82e-06 erg/cm² |
Fermi_GBM |
| fluence_error |
2.84e-08 erg/cm² |
Fermi_GBM |
| T100 |
19.6 s |
|
| GBM_located |
False |
|
| mjd |
58008.27344907408 |
GCN_circulars,Swift Det |
| Fermi GBM table |
|---|
| GRB_name_Fermi |
GRB170912273 |
| trigger_name |
bn170912273 |
| ra |
215.4592° |
| decl |
-61.9967° |
| pos_error |
3.14e+00° |
| datum |
2017-09-12 |
| t_trigger |
6:33:46.914 UTC |
| T90 |
13.568 s |
| T90_error |
1.557 s |
| T90_start |
6:33:46.914 UTC |
| fluence |
3.82e-06 erg/cm² |
| fluence_error |
2.84e-08 erg/cm² |
| flux_1024 |
8.80e+00 erg/cm²/s |
| flux_1024_error |
2.94e-01 erg/cm²/s |
| flux_1024_time |
-1.28e-01 erg/cm²/s |
| flux_64 |
1.19e+01 erg/cm²/s |
| flux_64_error |
1.35e+00 erg/cm²/s |
| IPN table |
|---|
| GRB_name |
GRB170912B |
| ra |
215.4667° |
| decl |
-62.0333° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB170912B |
| t_trigger |
6:33:46 UTC |
| ra |
215.4585° |
| decl |
-61.9969° |
| pos_error |
1.81e-04° |
| T90 |
19.6 s |
| fluence |
2.40e-06 erg/cm² |
| GCN 21864 table |
|---|
| GRB_name |
GRB170912B |
| GCN_number |
21864 |
| Detection_method |
Swift Det |
| t_trigger |
6:33:46 UTC |
| ra |
215.4660° |
| decl |
-62.0300° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21864
SUBJECT: GRB 170912B: Swift detection of a burst
DATE: 17/09/12 06:47:58 GMT
FROM: David Palmer at LANL
S. J. LaPorte (PSU), J. A. Kennea (PSU), P. T. O'Brien (U Leicester),
K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of
the Swift Team:
At 06:33:46 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 170912B (trigger=772052). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 215.466, -62.030 which is
RA(J2000) = 14h 21m 52s
Dec(J2000) = -62d 01' 47"
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 20 sec. The peak count rate
was ~9500 counts/sec (15-350 keV), at ~3 sec after the trigger.
The XRT began observing the field at 06:34:36.9 UT, 50.3 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 215.45921, -61.99674 which
is equivalent to:
RA(J2000) = 14h 21m 50.21s
Dec(J2000) = -61d 59' 48.3"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 120 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 does not constrain the column density.
The initial flux in the 2.5 s image was 4.76e-10 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 58 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 large, but uncertain extinction
expected.
Burst Advocate for this burst is S. J. LaPorte (extragsam AT gmail.com).
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 21868 table |
|---|
| GRB_name |
GRB170912B |
| GCN_number |
21868 |
| Detection_method |
Swift-XRT Det |
| ra |
215.4585° |
| decl |
-61.9971° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21868
SUBJECT: GRB 170912B: Enhanced Swift-XRT position
DATE: 17/09/12 10:59:09 GMT
FROM: Phil Evans at U of Leicester
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1328 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 170912B, 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 = 215.45854, -61.99709 which is equivalent
to:
RA (J2000): 14h 21m 50.05s
Dec (J2000): -61d 59' 49.5"
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 21872 table |
|---|
| GRB_name |
GRB170912B |
| GCN_number |
21872 |
| Detection_method |
Fermi GBM Det |
| t_trigger |
6:33:46.910 UTC |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21872
SUBJECT: GRB 170912B: Fermi GBM observations
DATE: 17/09/12 16:05:35 GMT
FROM: Peter Veres at UAH
P Veres (UAH), A von Kienlin (MPE) and C Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 06:33:46.91 UT on 12 September 2017, the Fermi Gamma-Ray Burst
Monitor triggered and located GRB 170912B (trigger 526890831 /
170912273) which was also detected by the Swift satellite (LaPorte et
al., GCN 21864). The GBM on-ground location is consistent with the
Swift position.
The angle from the Fermi LAT boresight at the GBM trigger
time is 39 degrees.
The GBM light curve shows multiple overlapping peaks
with a duration (T90) of about 13.3 s (50-300 keV).
The time-averaged spectrum from T0-1.7 s to T0+13.7 s is
best fit by a Band function with Epeak = 45.2 +/- 6.0 keV,
alpha = -0.88 +/- 0.23, and beta = -2.13 +/- 0.06.
The event fluence (10-1000 keV) in this time interval is
(4.5 +/- 0.2)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.1 s in the 10-1000 keV band
is 8.7 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
|
| GCN 21873 table |
|---|
| GRB_name |
GRB170912B |
| GCN_number |
21873 |
| Detection_method |
Swift-XRT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21873
SUBJECT: GRB 170912B: Swift-XRT refined Analysis
DATE: 17/09/12 16:08:31 GMT
FROM: Phil Evans at U of Leicester
S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), S.L. Gibson
(U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V.
D'Elia (ASDC) and S.J. LaPorte report on behalf of the Swift-XRT team:
We have analysed 6.5 ks of XRT data for GRB 170912B (LaPorte et al. GCN
Circ. 21864), from 45 s to 23.8 ks after the BAT trigger. The data
comprise 15 s in Windowed Timing (WT) mode (the first 3 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Osborne et
al. (GCN Circ. 21868).
The light curve can be modelled with an initial power-law decay with an
index of alpha=0.69 (+/-0.09), followed by a break at T+3083 s to an
alpha of 1.9 (+0.4, -0.3).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.7 (+/-0.3). The
best-fitting absorption column is 4.1 (+0.9, -0.8) x 10^22 cm^-2, in
excess of the Galactic value of 1.7 x 10^22 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 8.9 x 10^-11 (1.7 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.1 (+0.9, -0.8) x 10^22 cm^-2
Galactic foreground: 1.7 x 10^22 cm^-2
Excess significance: 4.8 sigma
Photon index: 1.7 (+/-0.3)
If the light curve continues to decay with a power-law decay index of
1.9, the count rate at T+24 hours will be 4.4 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.9 x
10^-14 (7.6 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/00772052.
This circular is an official product of the Swift-XRT team.
|
| GCN 21879 table |
|---|
| GRB_name |
GRB170912B |
| GCN_number |
21879 |
| Detection_method |
Swift-BAT Det |
| ra |
215.4640° |
| decl |
-61.9970° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21879
SUBJECT: GRB 170912B: Swift-BAT refined analysis
DATE: 17/09/13 01:42:01 GMT
FROM: Amy Lien at GSFC
D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
S. J. LaPorte (PSU), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+480 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170912B (trigger #772052)
(LaPorte et al., GCN Circ. 21864). The BAT ground-calculated position is
RA, Dec = 215.464, -61.997 deg which is
RA(J2000) = 14h 21m 51.3s
Dec(J2000) = -61d 59' 50.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted light curve shows several overlapping pulses that starts
at ~ T0 and ends at ~ T+40 s. T90 (15-350 keV) is 19.6 +- 6.2 sec
(estimated error including systematics).
The time-averaged spectrum from T-0.93 to T+38.75 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.88 +- 0.07. The fluence in the 15-150 keV band is 2.4 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.07 sec in the 15-150 keV band
is 5.7 +- 0.3 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/772052/BA/
|
| GCN 21881 table |
|---|
| GRB_name |
GRB170912B |
| GCN_number |
21881 |
| Detection_method |
Swift-UVOT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 21881
SUBJECT: GRB 170912B: Swift/UVOT Upper Limits
DATE: 17/09/14 02:44:20 GMT
FROM: Sam LaPorte at PSU
S. J. LaPorte (PSU) reports on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170912B
60 s after the BAT trigger (LaPorte et al., GCN Circ. 21864).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 21868)
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 57 207 147 >20.26
white 58 1024 332 >20.72
v 600 1074 58 >18.08
b 525 718 38 >18.76
u 269 1144 299 >19.67
uvw1 649 1124 58 >18.24
uvm2 624 1099 58 >18.12
uvw2 575 1050 58 >18.39
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 5.05 in the direction of the burst
(Schlegel et al. 1998).
[GCN OPS NOTE(14sep17): Per author's request, the typo in the Subject-line
was changed from "170712B" to "170912B".
|