GRB 150817A
GCN Circular 18160
Subject
GRB 150817A: AAO optical observations
Date
2015-08-18T19:09:15Z (11 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), R. Inasaridze (AAO), V. Ayvazian (AAO), I. Molotov
(KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up
collaboration:
We observed the field of the Swift GRB 150817A (D���Elia et al., GCN
18143) with AS-32 (0.7m) telescope of Abastumani Observatory starting on
Aug. 17 (UT) 17:00:31. Within the enhanced XRT error circle (Osborne et
al., GCN 18146) we do not detect the optical afterglow (Butler et al.,
GCN 18145; Cenko et al., GCN 18153). In particular the magnitude of the
first object (Butler et al., GCN 18144) is 21.6 +/- 0.2. Upper limit of
the object is following
Date UT start t-T0 Filter Exp. UL(3 sigam)
(mid, days) (s)
2015-08-17 17:00:31 0.64432 None 24*120 22.4
The photometry is based on nearby USNO-B1.0 stars
USNO-B.1_id R2
0779-0405699 16.12
0779-0405721 16.40
0779-0405742 16.47
0779-0405723 16.94
0779-0405664 17.60
GCN Circular 18158
Subject
GRB 150817A: LCOGT observations
Date
2015-08-18T18:03:36Z (11 years ago)
From
Simone Dichiara at Ferrara U/Italy <dichiara@fe.infn.it>
S. Dichiara, C. Guidorzi (U. Ferrara), C.G. Mundell (U. Bath),
S. Kobayashi (LJMU), A. Gomboc (U. Ljubljana) on behalf of
a large collaboration report:
The 1-m telescopes in Cerro Tololo (Chile) and McDonald (Texas)
began observing Swift GRB 150817A (V. D'Elia, et al., GCN 18143).
on August 17 at 03:16:31 UT, i.e. ~70 minutes since the BAT trigger,
with the r' and i' filters. Further observations with the i' filter
were performed using the 2-m Faulkes Telescope North ~400 min after
the trigger.
Within the enhanced XRT error circle (Osborne et al. GCN Circ. 18146)
we find no optical counterpart to the following limiting magnitude:
Mid time from Total Exp Filter Magnitude
trigger (min) (s)
-------------------------------------------------
75.9 120x9 r' > 19.6
86.3 120x8 i' > 18.5
107.6 120x5 r' > 19.7
119.2 120x5 i' > 19.1
408.1 120x5 i' > 20.7
-------------------------------------------------
Our results are consistent with the previous observations reported by
Butler et al. (GCN Circ. 18144) and Cenko et al. (GCN Circ. 18153).
Magnitudes are calibrated against nearby USNO-B1 stars (R2 and I).
GCN Circular 18156
Subject
GRB 150817A: Continued RATIR Optical Observations - Afterglow Confirmation
Date
2015-08-18T16:29:47Z (11 years ago)
Edited On
2024-11-07T20:00:23Z (2 years ago)
From
Alan M. Watson at Instituto de Astronomia UNAM <alan@astro.unam.mx>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (UCB), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM),
Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), Harvey Moseley (GSFC),
John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 150817A (D'Elia, et al., GCN 18143) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on
Sierra San Pedro Mártir from 2015/08 18.16 to 2015/08 18.27 UTC (25.78 to
28.42 hours after the BAT trigger), obtaining a total of 1.77 hours
exposure in the r, i, and z bands.
The first source reported by Butler et al. (GCN 18144) has not faded since
our first epoch of observations.
The second source, reported by Butler et al. (GCN 18145), has continued to
fade and is now only marginally detected. In comparison with the USNO-B1
and 2MASS catalogs, we obtain the following marginal detections and upper
limit (3-sigma):
r = 23.8 ± 0.4
i = 23.8 ± 0.3
z > 20.2
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
We note that the second source is consistent with the enhanced Swift-XRT
error circle (Osborne et al. GCN 18146). This coincidence and the clear
fading suggest that it is the afterglow of the GRB.
We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.
GCN Circular 18153
Subject
GRB 150817A: P60 Observations
Date
2015-08-18T13:30:21Z (11 years ago)
From
S. Bradley Cenko at NASA/GSFC <brad.cenko@nasa.gov>
S. B. Cenko (NASA/GSFC) and D. A. Perley (DARK) report on behalf of a larger collaboration:
We observed the location of GRB150817A (D�Elia et al., GCN 18143) with the robotic Palomar 60 inch telescope (P60). Observations began at 3:35 UT on 2015 Aug 17 (~ 90 min after the Swift trigger time). We detect a faint source at the location of the (second) candidate optical afterglow from RATIR (Butler et al., GCN 18145). Using nearby point sources from the APASS survey, we measure an i-band magnitude of 21.42 +/- 0.11 in a stacked frame at a median epoch of dt = 125 min after the Swift trigger.
GCN Circular 18150
Subject
GRB 150817A: Swift/UVOT Upper Limits
Date
2015-08-17T16:34:51Z (11 years ago)
From
Frank Marshall at GSFC <femarsha@khamseen.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC) and V. D'Elia (ASDC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150817A
3955 s after the BAT trigger (D'Elia et al., GCN Circ. 18143).
No optical afterglow consistent with the enhanced X-ray
position (Osborne et al. GCN Circ. 18146) or
the optical position (Butler et al. GCN Circ. 18145)
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 3955 4104 147 >20.5
white 3955 12079 930 >21.4
v 4111 28678 1278 >20.9
b 4932 17880 1723 >21.7
u 4727 23627 2613 >21.7
w1 4522 22957 2144 >21.0
w2 26865 27765 886 >20.5
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.48 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 18149
Subject
GRB 150817A: Fermi GBM observation
Date
2015-08-17T15:37:57Z (11 years ago)
From
Hoi-Fung Yu at MPE <sptfung@mpe.mpg.de>
H.-F. Yu (MPE) and P. Jenke (UAH) report on behalf of the Fermi GBM Team:
"At 02:05:08.40 UT on 17 August 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 150817A (trigger 461469912 / 150817087),
which was also detected by the Swift/BAT (D'Elia et al. 2015, GCN 18143).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 102 degrees.
This burst was also independently detected by INTEGRAL SPI-ACS.
The GBM light curve consists of multiple peaks with a duration (T90)
of about 36 s (50-300 keV). The time-averaged spectrum from
T0-10.240 s to T0+45.057 s is best fit by a power law function with
an exponential high-energy cutoff. The power law index is -1.34 +/- 0.06
and the cutoff energy, parameterized as Epeak, is 109.0 +/- 8.8 keV.
The event fluence (10-1000 keV) in this time interval
is (1.15 +/- 0.05)E-05 erg/cm^2. The 1.024-sec peak photon flux
measured starting from T0+16.256 s in the 10-1000 keV band
is 15.7 +/- 0.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 18148
Subject
GRB 150817A: Swift-BAT refined analysis
Date
2015-08-17T14:18:27Z (11 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
V. D'Elia (ASDC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
A. Y. Lien (GSFC/UMBC), 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-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 150817A (trigger #652334)
(D'Elia, et al., GCN Circ. 18143). The BAT ground-calculated position is
RA, Dec = 249.635, -12.050 deg, which is
RA(J2000) = 16h 38m 32.3s
Dec(J2000) = -12d 03' 01.7"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 71%.
The mask-weighted light curve shows multiple strong peaks starting at ~T-20,
with the brightest peak at ~T+12 sec and ending at ~T+70 sec.
T90 (15-350 keV) is 38.8 +- 2.1 sec (estimated error including systematics).
The time-averaged spectrum from T-16.76 to T+53.28 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.78 +- 0.04. The fluence in the 15-150 keV band is 5.9 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+11.22 sec in the 15-150 keV band
is 9.6 +- 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/652334/BA/
GCN Circular 18147
Subject
GRB 150817A: Swift-XRT refined Analysis
Date
2015-08-17T14:14:02Z (11 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), B.P. Gompertz
(U. Leicester), P. D'Avanzo (INAF-OAB), A. D'ai (INAF-IASFPA), T.G.R.
Roegiers (PSU), L.M. McCauley (PSU), J.A. Kennea (PSU) and V. D'Elia
report on behalf of the Swift-XRT team:
We have analysed 11 ks of XRT data for GRB 150817A (D'Elia et al. GCN
Circ. 18143), from 56 s to 29.2 ks after the BAT trigger. The data
comprise 32 s in Windowed Timing (WT) mode (the first 7 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. 18146).
The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=3.6 (+/-0.4). At T+104 s the decay
flattens to an alpha of 0.57 (+0.06, -1.00) before breaking again at
T+4285 s to a final decay with index alpha=1.07 (+/-0.07).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.77 (+/-0.11). The
best-fitting absorption column is 4.5 (+0.7, -0.6) x 10^21 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 4.5 x 10^-11 (6.4 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.5 (+0.7, -0.6) x 10^21 cm^-2
Galactic foreground: 2.7 x 10^21 cm^-2
Excess significance: 4.6 sigma
Photon index: 1.77 (+/-0.11)
If the light curve continues to decay with a power-law decay index of
1.07, the count rate at T+24 hours will be 0.021 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.7 x
10^-13 (1.4 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00652334.
This circular is an official product of the Swift-XRT team.
GCN Circular 18146
Subject
GRB 150817A: Enhanced Swift-XRT position
Date
2015-08-17T10:18:51Z (11 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1629 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 150817A, 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 = 249.63108, -12.05293 which is equivalent
to:
RA (J2000): 16h 38m 31.46s
Dec (J2000): -12d 03' 10.5"
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 Circular 18145
Subject
GRB 150817A: Continued RATIR Observations, Revised Candidate
Date
2015-08-17T06:16:09Z (11 years ago)
Edited On
2024-11-07T19:57:21Z (2 years ago)
From
Nat Butler at UC berkeley <natxbutler@gmail.com>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:
We continue to observe the field of GRB 150817A (V. D'Elia, et al., GCN 18143) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2015/08 17.14 to 2015/08 17.25 UTC (1.29 to 3.93 hours after the BAT trigger), obtaining a total of 2.13 hours exposure in the r, i, and z bands.
We note that the source reported in Butler et al. (GCN 18144) appears to have remained constant in flux over the time period quoted above, while an uncatalogued source just west of the XRT error circle has faded strongly as t^(-0.8+/-0.1). This second source is located at RA, Dec = 16:38:31.51, -12:03:9.6 (J2000, +/-0.5").
In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections and upper limit (3-sigma):
r = 22.06 +/- 0.09
i = 21.49 +/- 0.07
z > 20.33
These magnitudes, corresponding to the midpoint of our observation, are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.
GCN Circular 18144
Subject
GRB 150817A: RATIR Optical Afterglow Candidate
Date
2015-08-17T04:02:40Z (11 years ago)
Edited On
2024-11-07T18:56:46Z (2 years ago)
From
Nat Butler at UC berkeley <natxbutler@gmail.com>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report:
We observed the field of GRB 150817A (V. D'Elia, et al., GCN 18143) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2015/08 17.14 to 2015/08 17.16 UTC (1.29 to 1.70 hours after the BAT trigger), obtaining a total of 0.36 hours exposure in the r, i, and z bands.
We find an uncatalogued source within the Swift-XRT error circle at RA, Dec = 16:38:31.98, -12:3:11.5 (J2000, +/-0.5"). In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections and upper limit (3-sigma):
r = 21.50 +/- 0.20
i = 21.26 +/- 0.10
z > 17.83
These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.
Further observations are planned.
We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.
GCN Circular 18143
Subject
GRB 150817A: Swift detection of a burst
Date
2015-08-17T02:14:02Z (11 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
V. D'Elia (ASDC), S. D. Barthelmy (GSFC), N. Gehrels (NASA/GSFC),
L. Izzo (URoma/ICRA), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and
M. H. Siegel (PSU) report on behalf of the Swift Team:
At 02:05:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150817A (trigger=652334). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 249.643, -12.066 which is
RA(J2000) = 16h 38m 34s
Dec(J2000) = -12d 03' 55"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of at least 50 sec. The peak count rate
was ~17000 counts/sec (15-350 keV), at ~11 sec after the trigger.
The XRT began observing the field at 02:06:18.2 UT, 64.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 249.63352, -12.05336 which
is equivalent to:
RA(J2000) = 16h 38m 32.04s
Dec(J2000) = -12d 03' 12.1"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 56 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. We
cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.71 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 4.5
(+3.63/-3.05) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 1.27e-09 erg cm^-2 s^-1 (0.2-10
keV).
There will be no prompt UVOT data available for this burst.
Burst Advocate for this burst is V. D'Elia (delia AT asdc.asi.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.)