GRB 160228A
GCN Circular 19186
Subject
GRB 160228A: GROND afterglow confirmation and X-shooter host candidate redshift
Date
2016-03-14T17:46:43Z (10 years ago)
From
Thomas Kruehler at MPE Garching <kruehler@mpe.mpg.de>
T. Kruehler (MPE Garching), D. Malesani (DARK/NBI), D. Xu (NAOC/CAS),
J. Bolmer (MPE Garching), J. P. U. Fynbo, D. Perley (both DARK/NBI),
D. A. Kann (TLS Tautenburg), J. Greiner and J. F. Graham (both MPE
Garching) report on behalf of a larger collaboration:
We re-observed the field of GRB 160228A (Swift-trigger 676595,
Malesani et al. GCN #19107) with GROND mounted at the 2.2m MPG
telescope at ESO La Silla observatory. Simultaneous observations
in seven filters (g'r'i'z'JHK) started at 01:13 UT on 2016-03-03
(80 h after the GRB) and consisted of images with a total
integration time of 72 minutes in g'r'i'z' and 60 minutes in JHK.
The source reported as candidate afterglow in our earlier imaging
(Delvaux et al. GCN #19114) has faded beyond the detection limit
of the new data (r' > 25.1 mag in the AB system), confirming it
as the optical afterglow of GRB 160228A.
The nearby source (angular separation of 1.7") mentioned in
Delvaux et al. (GCN #19114) is still clearly present and located
at
RA (J2000.0) = 07:09:15.79
Dec. (J2000.0) = +26:55:52.4
with a preliminary brightness of r' = 24.2 +/- 0.3 mag.
The chance coincidence probability of finding an unrelated object
of this magnitude within a distance of 1.7" is 0.04
(following Bloom et al. 2002, AJ, 123, 1111), and we hence
consider this object as a host galaxy candidate of GRB 160228A.
While the chance coincidence probability is quite low, we note
that the angular separation would be unusually large for long GRBs.
A spectrum of the possible host was taken on 2016-03-12 with the VLT
equipped with the X-shooter spectrograph. The spectrum covers
the wavelength range 3000-20000 AA and has an exposure time of
4x1200 s. In the red part of the spectrum, we detect two emission
lines which we interpret as [O III] (5007) and Halpha at a common
redshift z = 1.64.
We acknowledge excellent support from the observing staff at
La Silla and Paranal, in particular Giovanni Carraro,
Boris Haeussler, Jose Velasquez, and Willem-Jan de Wit.
GCN Circular 19123
Subject
GRB 160228A: Swift/UVOT Upper Limits
Date
2016-02-29T22:50:24Z (10 years ago)
From
Frank Marshall at GSFC <femarsha@khamseen.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC) and D. Malesani (DARK/NBI)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 160228A
83 s after the BAT trigger (Malesani et al., GCN Circ. 19107).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 19110) or the
position of the GROND optical afterglow candidate
(Delvaux et al. GCN Circ. 19114)
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) exposures and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 83 233 147 >20.2
u_FC 296 546 246 >19.5
white 83 10111 342 >20.5
v 625 5975 236 >19.0
b 551 6695 138 >19.8
u 296 6589 462 >20.2
w1 675 6385 235 >19.8
m2 650 6179 236 >19.9
w2 601 5770 235 >19.8
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.06 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 19121
Subject
GRB160228A: Further analyses on spectral lag and extended emission
Date
2016-02-29T20:21:35Z (10 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
J. P. Norris (BSU), S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC),
N. Gehrels (GSFC), D. Malesani (DARK/NBI), T. Sakamoto (AGU),
and E. Troja (GSFC/UMCP) report:
We report on the spectral lag analysis of the initial pulse and extended
emission measurements of GRB 160228A (Malesani et al., GCN Circ. 19107).
Using a 32-ms binned light curve (which is the shortest time bin
possible for the lag analysis in this case), the lag of the initial pulse
(~T0 to ~T0+2 s) for the 100-350 keV to 25-50 keV bands is estimated
as 75 (+100/-60) ms (with 1-sigma error).
Despite the large error bars, the lag is inconsistent with zero, and thus
the lag of the initial pulse is much more consistent with those from a long
GRBs rather than short bursts (e.g., Norris et al. 2006).
Moreover, further analysis of the initial pulse intensity shows that it is
only a factor of several more intense than the extended emission in
both the 1-s binned and 32-ms binned light curves, which is much less
prominent than the usual short GRBs with extended emission (e.g.,
Norris et al. 2006).
GCN Circular 19120
Subject
GRB 160228A: Mondy optcial observations
Date
2016-02-29T19:42:16Z (10 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), E. Klunko (ISTP), A. Volnova (IKI), I. Korobtsev
(ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up
collaboration:
We observed the field of Swift GRB 160228A (Malesani et al., GCN 19107)
with AZT-33IK telescope of Sayan observatory (Mondy) starting on Feb.28
(UT) 18:31:31. Within enhanced XRT position (Beardmore et al., GCN
19110) we do not detect any optical object. In particular we do not
detect candidate of optical afterglow (Delvaux et al., GCN 19114). We
barely detect extended bluish object mentioned in (Delvaux et al., GCN
19114). Preliminary photometry of a combined image is following
Date UT start t-T0 Filter Exp. UL (3sigma)
(mid, days) (s)
2016-02-28 18:31:31 0.06044 R 60*60 22.2
Photometry is base on nearby USNO-B1.0 stars
USNO-B.1_id R2
1169-0155723 18.59
1169-0155657 19.12
1169-0155662 18.92
1168-0146568 18.65
1169-0155709 19.49
GCN Circular 19119
Subject
GRB 160228A: RATIR Optical and NIR Observations
Date
2016-02-29T18:20:16Z (10 years ago)
From
Nat Butler at UC berkeley <natxbutler@gmail.com>
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (GSFC/STScI),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos�� A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes��s Gonz��lez (UNAM),
Carlos Rom��n-Z����iga (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 160228A (Malesani et al., GCN Circular 19107)
with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astron��mico
Nacional on Sierra San Pedro M��rtir from 2016/02 29.12 to 2016/02 29.38 UTC
(9.23 to 15.50 hours after the BAT trigger), obtaining a total of 4.27
hours exposure in the r and i bands and 1.79 hours exposure in the Z, Y, J,
and H bands.
For a source within the Swift-XRT error circle, in comparison with the
USNO-B1 and 2MASS catalogs, we obtain the following 3-sigma upper limits:
r > 24.46
i > 24.39
Z > 23.21
Y > 22.76
J > 22.43
H > 22.10
These magnitudes are in the AB system and are not corrected for
Galactic extinction in the direction of the GRB.
We do not detect the candidate afterglow seen by Delvaux et al. (GCN Circ
19114) with GROND. Our upper-limits in rZJH are above their detections.
However, there is weak evidence for fading in i, since GROND detected i =
23.8 �� 0.2 at about 7.5 hours and we obtain i > 24.4 at 12.4 hours.
We see suggestions of the "extended bluish object��� mentioned by Delvaux et
al. in our r-band image. We also clearly detect the "larger, brighter
galaxy��� at 07:09:15.89 +26:55:59.3 (��0.5���) with:
r = 22.64 �� 0.07
i = 22.17 �� 0.05
Z = 22.07 �� 0.13
Y = 21.69 �� 0.14
J = 21.60 �� 0.17
H = 21.64 �� 0.24
We thank the staff of the Observatorio Astron��mico Nacional in San
Pedro M��rtir.
GCN Circular 19118
Subject
GRB 160228A: MASTER-Amur prompt observations
Date
2016-02-29T18:04:58Z (10 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
A.Gabovich, V.Yurkov, Yu.Sergienko, D.Varda
Blagoveschensk Educational State University, Blagoveschensk
V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov,
P.Balanutsa, A.Kuznetsov, D.Kuvshinov
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University
V.Krushinski, I.Zalozhnich, A. Popov
Ural State University, Kourovka
K.Ivanov, N.M.Budnev, O.Gres, V.A.Poleshchuk
Irkutsk State University
A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
MASTER-Amur robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in Blagoveschensk was pointed to the GRB160228A 20 sec after
notice time and 40 sec after trigger time at 2016-02-28 17:35:12 UT. On
our first (10s exposure) set we haven`t found optical transient within
SWIFT error-box (Malesani et al., GCN 19107) and at GROND OT
position (Delvaux et al., GCN 19114).
The 5-sigma upper limit has been about 15.1 mag (unfilterd).
We have 3 images during extended emission (Stamatikos et al., GCN 19113)
with limit 15.2 .
The message may be cited.
GCN Circular 19117
Subject
GRB 160228A: Swift-XRT refined Analysis
Date
2016-02-29T17:46:02Z (10 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A.P. Beardmore (U.
Leicester), P.A. Evans (U. Leicester), S.L. Gibson (U. Leicester), A.
Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB),
T.G.R. Roegiers (PSU) and D. Malesani report on behalf of the Swift-XRT
team:
We have analysed 5.9 ks of XRT data for GRB 160228A (Malesani et al.
GCN Circ. 19107), from 63 s to 40.4 ks after the BAT trigger. The data
comprise 129 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. 19108).
The light curve can be modelled with an initial power-law decay with an
index of alpha=1.01 (+0.26, -0.32), followed by a break at T+125 s to
an alpha of 2.94 (+0.16, -0.14).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.22 (+0.18, -0.16). The
best-fitting absorption column is 2.6 (+1.8, -1.3) x 10^21 cm^-2, in
excess of the Galactic value of 9.0 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.63 (+0.30, -0.28)
and a best-fitting absorption column of 1.8 (+1.4, -0.9) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 4.4 x 10^-11 (5.2 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 1.8 (+1.4, -0.9) x 10^21 cm^-2
Galactic foreground: 9.0 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.63 (+0.30, -0.28)
If the light curve continues to decay with a power-law decay index of
2.94, the count rate at T+24 hours will be 7.1 x 10^-8 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.1 x
10^-18 (3.7 x 10^-18) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00676595.
This circular is an official product of the Swift-XRT team.
GCN Circular 19114
Subject
GRB 160228A: GROND Afterglow Candidate
Date
2016-02-29T05:47:40Z (10 years ago)
From
Corentin Delvaux at MPE <delvaux@mpe.mpg.de>
C. Delvaux, T. Schweyer (both MPE Garching), D. A. Kann (TLS Tautenburg),
and J. Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 160228A (Swift trigger 676595; Malesani et
al., GCN #19107) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2m MPG telescope at the ESO La Silla
Observatory (Chile).
Observations started at 00:02 UT on 2016-02-29, 6.4h after the GRB
trigger. They were performed at an average seeing of 1.2" and at an
average airmass of 1.9.
We detect a single source at the edge of the Swift-XRT error circle
reported by Beardmore et al. (GCN #19110) at
RA (J2000.0) = 07h09m15.82s
Dec. (J2000.0) = +26d55'53.8"
with an uncertainty of 0.2" in each coordinate.
Based on 132 min of exposure in g'r'i'z' and 110 min in JHK, at a mid-time
of 01:46 UT, we derive the following preliminary magnitudes and upper
limits (in AB system):
g' = 24.4 +/- 0.1 mag,
r' = 24.4 +/- 0.1 mag,
i' = 23.8 +/- 0.2 mag,
z' = 24.1 +/- 0.3 mag,
J > 22.3 mag,
H > 21.6 mag, and
K > 19.4 mag.
We note the presence of a very close-by (separation < 2") extended bluish
object, lying outside the Swift-XRT error circle, which could be the host
galaxy of the candidate. Another host could be a larger, brighter galaxy
lying at the north of the Swift-XRT error circle (separation ~ 6.6").
We found no evidence of fading of the candidate. Therefore, we cannot
affirm the detected source is the optical afterglow.
Given detections and upper limits are calibrated against GROND zeropoints
as well as 2MASS field stars. No correction for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V)=0.056 mag in
the direction of the burst (Schlafly & Finkbeiner 2011) has been applied.
GCN Circular 19113
Subject
GRB 160228A: Swift-BAT refined analysis
Date
2016-02-29T04:53:26Z (10 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
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),
D. Malesani (DARK/NBI), C. B. Markwardt (GSFC), 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 160228A (trigger #676595)
(Malesani et al., GCN Circ. 19107). The BAT ground-calculated position is
RA, Dec = 107.311, 26.946 deg which is
RA(J2000) = 07h 09m 14.6s
Dec(J2000) = +26d 56' 45.3"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 81%.
The mask-weighted light curve shows a short spike from ~T0 to ~T+3 s, followed
by an extended emission till ~T+120 s. This structure is similar to those short
GRBs with extended emission (e.g., Norris et al. 2006). T90 (15-350 keV) is
98.36 +- 23.35 sec (estimated error including systematics).
The time-averaged spectrum from T-0.01 to T+116.104 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.31 +- 0.11. The fluence in the 15-150 keV band is (2.0 +- 0.1) x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.01 sec in the 15-150 keV band
is 1.2 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
Moreover, spectral analyses for the short pulse and extended emission intervals
show that the short pulse is harder than the extended emission. Both the
short-pulse spectrum (T0-0.008 to T0+3.188 s) and the extended-emission spectrum
(T0+3.188 to T0+116.104 s) are best fit by the simple power-law model,
with the power-law index of (0.88 +/- 0.17) and (1.35 +/- 0.12), respectively.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/676595/BA/
GCN Circular 19112
Subject
GRB 160228A: optical observations
Date
2016-02-28T21:04:19Z (10 years ago)
From
Klaas Wiersema at U Leicester <kw113@leicester.ac.uk>
K. Wiersema (University of Leicester) reports on behalf of the Oadby
Transients Team:
We observed the field of GRB 160228A (Malesani et al. GCN 19107) using the
0.5m telescope at the observatory of the University of Leicester, at Oadby (UK).
In a series of V band exposures, starting at 19:52 UT on 28 February 2016 (~2.3 hours
after burst), we find no source in or near the XRT error circle (Beardmore et al.
GCN 19110) to a limit of V<19.5 mag.
GCN Circular 19110
Subject
GRB 160228A: Enhanced Swift-XRT position
Date
2016-02-28T20:07:17Z (10 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 732 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 160228A, 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 = 107.31636, +26.93173 which is equivalent
to:
RA (J2000): 07h 09m 15.93s
Dec (J2000): +26d 55' 54.2"
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 Circular 19108
Subject
GRB 160228A: Prompt enhanced Swift-XRT position
Date
2016-02-28T18:05:53Z (10 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 160228A, we find an
enhanced XRT position of the afterglow: RA, Dec: 107.3162, 26.9317
which is equivalent to:
RA (J2000) = 07 09 15.90
Dec (J2000) = +26 55 54.0
with an uncertainty of 2.1 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/676595.
Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.
GCN Circular 19107
Subject
GRB 160228A: Swift detection of a burst
Date
2016-02-28T17:46:31Z (10 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
D. Malesani (DARK/NBI), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC),
L. M. McCauley (PSU), D. M. Palmer (LANL), T. G. R. Roegiers (PSU) and
B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team:
At 17:34:32 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 160228A (trigger=676595). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 107.322, +26.956 which is
RA(J2000) = 07h 09m 17s
Dec(J2000) = +26d 57' 23"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows several separated peaks
with a total duration of about 30 sec. The peak count rate
was ~4200 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 17:35:45.5 UT, 73.1 seconds after
the BAT trigger. Using promptly downlinked data we find a bright, fading,
uncatalogued X-ray source located at RA, Dec 107.31671, 26.93103 which
is equivalent to:
RA(J2000) = 07h 09m 16.01s
Dec(J2000) = +26d 55' 51.7"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 91 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 9.03
x 10^20 cm^-2 (Willingale et al. 2013).
The initial flux in the 2.5 s image was 1.37e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of nominal 150.000 seconds with the White
filter starting 83 seconds after the BAT trigger. No credible afterglow
candidate has been found in the initial data products. Data from the 2.7'x2.7'
sub-image are not available at this time. 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 0.06.
Burst Advocate for this burst is D. Malesani (malesani AT dark-cosmology.dk).
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.)