| Summary table |
|---|
| Variable |
Value |
Source |
| T0 |
4:42:27 UTC |
GCN_circulars,Swift Det |
| ra |
107.5647° |
Swift |
| decl |
-22.4491° |
Swift |
| pos_error |
1.94e-04° |
Swift |
| T90 |
27.6 s |
Swift |
| T90_start |
4:42:27 UTC |
Swift |
| fluence |
5.50e-07 erg/cm² |
Swift |
| T100 |
27.6 s |
|
| GBM_located |
False |
|
| mjd |
57188.19614583333 |
GCN_circulars,Swift Det |
| IPN table |
|---|
| GRB_name |
GRB150615A |
| ra |
107.5708° |
| decl |
-22.4667° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB150615A |
| t_trigger |
4:42:27 UTC |
| ra |
107.5647° |
| decl |
-22.4491° |
| pos_error |
1.94e-04° |
| T90 |
27.6 s |
| fluence |
5.50e-07 erg/cm² |
| GCN 17923 table |
|---|
| GRB_name |
GRB150615A |
| GCN_number |
17923 |
| Detection_method |
Swift Det |
| t_trigger |
4:42:27 UTC |
| ra |
107.5700° |
| decl |
-22.4720° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 17923
SUBJECT: GRB 150615A: Swift detection of a burst
DATE: 15/06/15 05:00:00 GMT
FROM: David Palmer at LANL
E. Troja (NASA/GSFC/UMCP), S. D. Barthelmy (GSFC),
A. D'Ai (INAF-IASFPA), A. Maselli (INAF-IASFPA), D. M. Palmer (LANL),
T. Sakamoto (AGU), B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU)
report on behalf of the Swift Team:
At 04:42:27 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150615A (trigger=643833). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 107.570, -22.472 which is
RA(J2000) = +07h 10m 17s
Dec(J2000) = -22d 28' 18"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single-peaked
structure with a duration of about 20 sec. The peak count rate
was ~1000 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 04:44:22.0 UT, 115.0 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
107.5645, -22.4497 which is equivalent to:
RA(J2000) = 07h 10m 15.48s
Dec(J2000) = -22d 26' 58.8"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 82 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 4.74
x 10^21 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 3.94e-10 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 122 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
0.33.
Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov).
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 17924 table |
|---|
| GRB_name |
GRB150615A |
| GCN_number |
17924 |
| Detection_method |
Swift-XRT Det |
| ra |
107.5650° |
| decl |
-22.4491° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 17924
SUBJECT: GRB 150615A: Enhanced Swift-XRT position
DATE: 15/06/15 08:34:51 GMT
FROM: Phil Evans at U of Leicester
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1338 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 150615A, 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 = 107.56503, -22.44906 which is equivalent
to:
RA (J2000): 07h 10m 15.61s
Dec (J2000): -22d 26' 56.6"
with an uncertainty of 1.9 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 17925 table |
|---|
| GRB_name |
GRB150615A |
| GCN_number |
17925 |
| Detection_method |
Swift-UVOT Det |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 17925
SUBJECT: GRB 150615A: Swift/UVOT Detection
DATE: 15/06/15 13:44:32 GMT
FROM: Samantha Oates at MSSL
S. R. Oates (IAA-CSIC/UCL-MSSL) and E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150615A
122 s after the BAT trigger (Troja et al., GCN Circ. 17923).
A faint source consistent with the enhanced XRT position
(Beardmore et al. GCN Circ. 17924) is detected in the
combined white exposures.
Preliminary detection and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 122 1532 392 20.64 +/- 0.19
v 611 1409 97 >18.3
b 536 1507 97 >19.9
u 280 1482 324 >20.2
w1 660 1458 97 >19.2
m2 635 1433 97 >18.9
w2 586 1557 117 >19.4
The magnitudes in the table are not corrected for the significant Galactic
extinction due to the reddening of E(B-V) = 0.33 in the direction of the burst
(Schlegel et al. 1998).
|
| GCN 17928 table |
|---|
| GRB_name |
GRB150615A |
| GCN_number |
17928 |
| Detection_method |
Swift-XRT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 17928
SUBJECT: GRB 150615A: Swift-XRT refined Analysis
DATE: 15/06/15 18:01:50 GMT
FROM: Alessandro Maselli at INAF/IASF Palermo
A. Maselli (INAF-IASFPA), A. D'Ai (INAF-IASFPA), P.A. Evans (U.
Leicester), B. Sbarufatti (INAF-OAB/PSU), A. Amaral-Rogers (U.
Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.
Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), J.A.
Kennea (PSU) and E. Troja (NASA/GSFC/UMCP) report on behalf of the
Swift-XRT team:
We have analysed 10 ks of XRT data for GRB 150615A (Troja et al. GCN
Circ. 17923), from 102 s to 30.3 ks after the BAT trigger. The data
comprise 74 s in Windowed Timing (WT) mode (the first 8 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 Beardmore
et al. (GCN Circ. 17924).
The light curve can be modelled with an initial power-law decay with an
index of alpha=3.08 (+0.28, -0.20), followed by a break at T+626 s to
an alpha of 0.17 (+0.08, -0.09).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.48 (+0.25, -0.19). The
best-fitting absorption column is 5.03 (+1.17, -0.29) x 10^21 cm^-2,
consistent with the Galactic value of 4.7 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 3.2 x 10^-11 (7.3 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 5.03 (+1.17, -0.29) x 10^21 cm^-2
Galactic foreground: 4.7 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.48 (+0.25, -0.19)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00643833.
This circular is an official product of the Swift-XRT team.
|
| GCN 17930 table |
|---|
| GRB_name |
GRB150615A |
| GCN_number |
17930 |
| Detection_method |
Swift-BAT Det |
| ra |
107.5540° |
| decl |
-22.4660° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 17930
SUBJECT: GRB 150615A, Swift-BAT refined analysis
DATE: 15/06/15 21:05:48 GMT
FROM: Amy Lien at GSFC
T. Sakamoto (AGU), 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),
M. Stamatikos (OSU), E. Troja (NASA/GSFC/UMCP), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-640 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150615A (trigger #643833)
(Troja, et al., GCN Circ. 17923). The BAT ground-calculated position is
RA, Dec = 107.554, -22.466 deg which is
RA(J2000) = 07h 10m 12.8s
Dec(J2000) = -22d 27' 57.6"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 85%.
The mask-weighted light curve shows a single pulse that starts at ~ T-3 s,
peaks at ~T+5 s, and ends at ~T+30 s. T90 (15-350 keV) is 27.6 +- 5.1 sec
(estimated error including systematics).
The time-averaged spectrum from T-2.9 to T+30.1 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.84 +- 0.21. The fluence in the 15-150 keV band is 5.5 +- 0.7 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+5.80 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/643833/BA/
|