| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
22:41:48 UTC |
GCN_circulars,Swift Det |
| ra |
82.9661° |
Swift |
| decl |
-5.3892° |
Swift |
| pos_error |
1.81e-04° |
Swift |
| T90 |
426.0 s |
Swift |
| T90_start |
22:41:48 UTC |
Swift |
| fluence |
3.10e-06 erg/cm² |
Swift |
| T100 |
426.0 s |
|
| GBM_located |
False |
|
| mjd |
57235.94569444445 |
GCN_circulars,Swift Det |
| IPN table |
|---|
| GRB_name |
GRB150801B |
| ra |
82.9583° |
| decl |
-5.3833° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB150801B |
| t_trigger |
22:41:48 UTC |
| ra |
82.9661° |
| decl |
-5.3892° |
| pos_error |
1.81e-04° |
| T90 |
426.0 s |
| fluence |
3.10e-06 erg/cm² |
| GCN 18104 table |
|---|
| GRB_name |
GRB150801B |
| GCN_number |
18104 |
| Detection_method |
Swift Det |
| t_trigger |
22:41:48 UTC |
| ra |
82.9590° |
| decl |
-5.3870° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 18104
SUBJECT: GRB 150801B: Swift detection of a burst
DATE: 15/08/01 22:58:56 GMT
FROM: Scott Barthelmy at NASA/GSFC
B. Sbarufatti (INAF-OAB/PSU), S. D. Barthelmy (GSFC),
J. R. Cummings (NASA/UMBC), L. M. Z. Hagen (PSU),
N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Swift Team:
At 22:41:48 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150801B (trigger=650977). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 82.959, -5.387 which is
RA(J2000) = 05h 31m 50s
Dec(J2000) = -05d 23' 14"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows several overlapping peaks
with a total duration of about 20 sec. The peak count rate
was ~2600 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 22:43:07.3 UT, 78.8 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 82.9666, -5.3883 which
is equivalent to:
RA(J2000) = 05h 31m 51.99s
Dec(J2000) = -05d 23' 18.0"
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This
location is 27 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.
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 83 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 19.6 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
0.24.
We note that this event is in the vicinity of the Orion Nebula.
However, it appears in all other respects to be a typical GRB.
Burst Advocate for this burst is B. Sbarufatti (boris.sbarufatti AT brera.inaf.it).
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 18108 table |
|---|
| GRB_name |
GRB150801B |
| GCN_number |
18108 |
| Detection_method |
Swift-XRT Det |
| ra |
82.9662° |
| decl |
-5.3893° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 18108
SUBJECT: GRB 150801B: Enhanced Swift-XRT position
DATE: 15/08/02 02:52:40 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 1630 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 150801B, 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 = 82.96622, -5.38930 which is equivalent
to:
RA (J2000): 05h 31m 51.89s
Dec (J2000): -05d 23' 21.5"
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 18109 table |
|---|
| GRB_name |
GRB150801B |
| GCN_number |
18109 |
| Detection_method |
Swift-XRT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 18109
SUBJECT: GRB 150801B: Swift-XRT refined Analysis
DATE: 15/08/02 18:14:27 GMT
FROM: Boris Sbarufatti at INAF-OAB/IASFPA
P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), T.G.R. Roegiers (PSU), L.M.
McCauley (PSU), J.A. Kennea (PSU), B.P. Gompertz (U. Leicester), J.P.
Osborne (U. Leicester), A. D'ai (INAF-IASFPA) and B. Sbarufatti
(INAF-OAB/PSU) report on behalf of the Swift-XRT team:
We have analysed 12 ks of XRT data for GRB 150801B (Sbarufatti et al.
GCN Circ. 18104), from 64 s to 40.0 ks after the BAT trigger. We have
analysed 12 ks of XRT data for GRB 150801B (Sbarufatti et al. GCN Circ.
18104), from 64 s to 40.0 ks after the BAT trigger. The data comprise
8 s in Windowed Timing (WT) mode while Swift was slewing to the burst,
270 s in PC mode, a further 185 s in WT mode during a bright flare
starting at T0+366 s (also seen in the BAT), with the remainder 11.5 ks
in Photon Counting (PC) mode. The enhanced XRT position for this burst
was given by Evans et al. (GCN Circ. 18108).
The late-time light curve (from T0+4.9 ks) can be modelled with a
power-law decay with a decay index of alpha=1.74 (+0.18, -0.17).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.79 (+0.21, -0.19). The
best-fitting absorption column is 3.0 (+/-0.4) x 10^22 cm^-2, in
excess of the Galactic value of 2.7 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 (1.5 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 3.0 (+/-0.4) x 10^22 cm^-2
Galactic foreground: 2.7 x 10^21 cm^-2
Excess significance: 10.8 sigma
Photon index: 1.79 (+0.21, -0.19)
If the light curve continues to decay with a power-law decay index of
1.74, the count rate at T+24 hours will be 1.4 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x
10^-13 (2.2 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/00650977.
This circular is an official product of the Swift-XRT team.
|
| GCN 18110 table |
|---|
| GRB_name |
GRB150801B |
| GCN_number |
18110 |
| Detection_method |
Swift-BAT Det |
| ra |
82.9610° |
| decl |
-5.3740° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 18110
SUBJECT: GRB 150801B: Swift-BAT refined analysis
DATE: 15/08/02 19:47:20 GMT
FROM: Jay R. Cummings at NASA/GSFC/Swift
S. D. Barthelmy (GSFC), J. R. Cummings (CPI), 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),
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 150801B (trigger #650977) (Sbarufatti,
et al., GCN Circ. 18104). The BAT ground-calculated position is
RA, Dec = 82.961, -5.374 deg which is
RA(J2000) = 05h 31m 50.7s
Dec(J2000) = -05d 22' 28.0"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 62%.
The mask-weighted light curve shows two widely separated episodes. The first
episode was about 40 seconds long starting at about T-20 seconds. There were two
prominent overlapping FRED peaks at T0 and T+10 seconds, followed by a return to
background level. The second episode became detectable in BAT at about T+330
seconds and returned to background about T+450 seconds. There were two smaller
cusp-shaped peaks at T+370 and T+390 seconds, about 10 and 7 seconds long. The
peaks between 330 and 450 seconds are at the same time as bright X-ray flares
detected by XRT. T90 (15-350 keV) was 426 +- 30 sec (estimated error including
systematics).
The time-averaged spectrum from T-30.16 to T+433.94 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.84 +- 0.14. The fluence in the 15-150 keV band is 3.1 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+9.32 sec in the 15-150 keV band
is 2.5 +- 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/650977/BA/
|
| GCN 18111 table |
|---|
| GRB_name |
GRB150801B |
| GCN_number |
18111 |
| Detection_method |
Swift-UVOT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 18111
SUBJECT: GRB 150801B: Swift/UVOT Upper Limits
DATE: 15/08/02 22:58:24 GMT
FROM: Lea Hagen at PSU
L. M. Z. Hagen (PSU) and B. Sbarufatti (INAF-OAB/PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150801B
84 s after the BAT trigger (Sbarufatti et al., GCN Circ. 18104).
No optical afterglow consistent with the XRT position (Evans et al.,
GCN Circ. 18108) 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 83 233 147 >20.17
white 575 12513 1345 >21.35
v 625 16812 901 >19.63
b 551 11601 1264 >20.68
u_FC 295 545 245 >19.42
u 699 7399 490 >19.53
uvw1 1105 7194 432 >19.41
uvw2 4943 13218 884 >19.89
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.24 in the direction of the burst
(Schlegel et al. 1998).
|