GRB 150728A
GCN Circular 18115
Subject
GRB 150728A: TNG optical observations
Date
2015-08-05T20:10:52Z (10 years ago)
From
Paolo D'Avanzo at INAF-OAB <paolo.davanzo@brera.inaf.it>
P. D'Avanzo, D. Fugazza (INAF/OABr), V. D'Elia (INAF/OAR and ASI/ASDC), V. Lorenzi, H. Stoev (INAF/TNG) report on behalf of the CIBO collaboration:
We observed the field of the short GRB 150728A (Krimm et al., GCN 18087; Ukwatta et al. GCN 18091) with the 3.6m TNG telescope equipped with the DOLoRes camera. Observations consisted of 12 images in the r-sdss band for a total of 48 min exposure. The seeing was ~1.2".
No object is detected within the enhanced XRT position (Beardmore et al., GCN 18088), down to a limiting magnitude r > 24.5 (calibrated against nearby USNO-B1 stars). The mean time of the observation was 2015 Jul 30.9439 UT (2.41 days after the GRB). In particular, we find no evidence for fading for the object reported by Dichiara et al. in GCN 18090 (which appears to be point-like in our images), by measuring in our dataset a magnitute of r = 21.4 +/- 0.1 for this source (calibrated against nearby USNO-B1 stars).
GCN Circular 18098
Subject
GRB 150728A: Continued RATIR Optical Observations
Date
2015-07-31T17:52:51Z (10 years ago)
Edited On
2024-11-07T19:47:20Z (a year 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), Chris Klein (UCB), 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),
and Harvey Moseley (GSFC) report:
We observed the field of GRB 150728A (Krimm et al., GCN 18087) 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 2015/07 31.22 to 2015/07 31.46 UTC (64.53 to
70.24 hours after the BAT trigger), obtaining a total of 3.60 hours
exposure in the r, i, and z bands.
For source A of Watson et al. (GCN 18096), we determine:
r 21.26 ± 0.04
i 20.90 ± 0.04
z 19.43 ± 0.13
For source B of Watson et al. (GCN 18096), we determine:
r 20.91 ± 0.04
i 20.70 ± 0.04
z 20.48 ± 0.31
These magnitudes are in comparison with the USNO-B1 and 2MASS catalogs,
are in the AB system, and are not corrected for Galactic extinction in the
direction of the GRB.
Our source A appears to correspond to the source reported by Dichiara et
al. (GCN 18090). If this association is correct, then there is little
evidence for fading between observations at about 1 hour, 16-23 hours, and
65-70 hours. This is in contrast to the suggestion of Mazaeva et al. (GCN
18097), who suggested that source A might indeed be the fading afterglow
on the basis of a 3-sigma non-detection at 30 hours.
Similarly, there is little evidence for fading of source B between 16-23
hours and 65-70 hours.
We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.
GCN Circular 18097
Subject
GRB 150728A: TSHAO optical observations
Date
2015-07-30T18:41:10Z (10 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), I. Reva (Fesenkov Astrophysical Institute), A.
Volnova (IKI), A. Pozanenko (IKI) report on behalf of larger GRB
follow-up collaboration:
We observed the field of the Swift GRB 150728A (Krimm et al. GCN 18087)
with Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical
Observatory starting on Jul. 29 (UT) 18:34:50. We obtained several
images in R-filter. In a combined image we do not detect the FTN object
(Dichiara et al. GCN 18090) also visible in AAO observations (Mazaeva et
al., GCN 18094) and source A in RATIR observations (Watson et al., GCN
18096).
A photometry of the field is following
Date UT start t-T0 Filter Exp. ULimit (3sigma)
(mid, days) (s)
2015-07-29 18:34:50 1.26425 R 15*300 21.2
The photometry is based on nearby USNO-B1.0 stars
USNO-B.1_id R2
1239-0338943 17.06
1239-0338998 16.69
Also we marginally detect object B of the RATIR observations (Watson
et al., GCN 18096) in our current and previous observation of the field
(Mazaeva et al., GCN 18094).
The finding chart can be found in
http://grb.rssi.ru/GRB150728A/GRB150728A_AAO_left_TSHAO_right.png
Would the source A be a non-variable point like object with magnitudes
of r=21.37+/-0.04 and i=20.89+/-0.04 (Watson et al., GCN 18096) in
our observation the object A might be detected as the object with a
magnitude less than R=21.3 (3 sigma). So we tentatively suggest the
object A as an afterglow candidate.
GCN Circular 18096
Subject
GRB 150728A: RATIR Optical Observations
Date
2015-07-29T20:07:03Z (10 years ago)
Edited On
2024-11-07T18:57:12Z (a year ago)
From
Alan M. Watson at Instituto de Astronomia UNAM <alan@astro.unam.mx>
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>
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), 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),
and Harvey Moseley (GSFC) report:
We observed the field of GRB 150728A (Krimm et al., GCN 18087) 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 2015/07 29.19 to 2015/07 29.48 UTC (15.73 to
22.75 hours after the BAT trigger), obtaining a total of 5.29 hours
exposure in the r, i, and z bands.
The brightest source within the enhanced Swift/XRT error circle (Beardmore
et al., GCN 18088) is the cataloged source 2MASS 19285425+3354576, for
which we determine a position of 19:28:54.26 +33:54:57.6 (J2000, �0.5")
and magnitudes:
r 16.71 ± 0.02
i 16.49 ± 0.01
z 16.14 ± 0.04
We detect two other uncataloged sources on the edge of the error circle.
For source A we determine a position of 19:28:54.80 +33:54:58.2 (J2000,
�0.5") and magnitudes:
r 21.37 ± 0.04
i 20.89 ± 0.04
z 19.54 ± 0.13
and for source B we determine 19:28:54.25 +33:55:2.6 (J2000, �0.5") and:
r 21.11 ± 0.04
i 20.73 ± 0.03
z 20.21 ± 0.21
These magnitudes are in comparison with the USNO-B1 and 2MASS catalogs,
are in the AB system, and are not corrected for Galactic extinction in the
direction of the GRB.
Our source A appears to correspond to the source reported by Dichiara et
al. (GCN 18090). If this association is correct, then there is little
evidence for fading between about 1 hour and 16-23 hours.
We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.
GCN Circular 18094
Subject
GRB 150728A: AAO optical observations
Date
2015-07-29T18:30:31Z (10 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Mazaeva (IKI), R. Inasaridze (AAO), Sh. Makandarashvili (AAO), A.
Volnova (IKI), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of
larger GRB follow-up collaboration:
We observed the field of the Swift GRB 150728A (Krimm et al. GCN 18087)
with AS-32 (0.7m) telescope of Abastumani Observatory starting on Jul.
28 (UT) 19:32:14. Within the enhanced XRT error circle (Beardmore et
al. GCN 18088) we detected the object coinciding with the object found
by FTN (Dichiara et al. GCN 18090). A photometry of the object is following
Date UT start t-T0 Filter Exp. OT
(mid, days) (s)
2015-07-28 19:32:14 0.30491 None 28*120 20.6+/-0.25
The photometry is based on nearby USNO-B1.0 stars
USNO-B.1_id R2
1239-0338943 17.06
1239-0338998 16.69
The photometry could be biased by nearby star. Presently we cannot say
nothing about variability of the object and more observation is
necessary to confirm/reject the object as afterglow of GRB 150728A.
GCN Circular 18093
Subject
GRB 150728A: Swift-XRT refined Analysis
Date
2015-07-29T01:14:03Z (10 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
C. Pagani (U. Leicester), A. Maselli (INAF-IASFPA), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N.
Burrows (PSU), T.G.R. Roegiers (PSU), A.P. Beardmore (U. Leicester),
P.A. Evans (U. Leicester) and H.A. Krimm report on behalf of the
Swift-XRT team:
We have analysed 6.7 ks of XRT data for GRB 150728A (Krimm et al. GCN
Circ. 18087), from 79 s to 30.0 ks after the BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Beardmore et al. (GCN Circ. 18088). The source
is fading with alpha >0.4.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00650617.
This circular is an official product of the Swift-XRT team.
GCN Circular 18092
Subject
GRB 150728A: Swift/UVOT Upper Limits
Date
2015-07-28T21:08:25Z (10 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and H. A. Krimm (CRESST/GSFC/USRA) report on
behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 150728A 75
s after the BAT trigger (Krimm et al., GCN Circ. 18087).
No optical afterglow consistent with the XRT position (Beardmore et al.
GCN Circ. 18088) or the Faulkes position (Dichiara et al. GCN Circ.
18090) 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 75 225 147 >21.3
u_FC 288 537 246 >20.4
white 75 6991 730 >22.0
v 617 5982 275 >19.8
b 543 6803 452 >21.1
u 288 6597 678 >21.0
w1 668 6392 452 >20.4
m2 643 6187 452 >20.2
w2 593 5777 255 >20.1
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.20 in the direction of the
burst (Schlegel et al. 1998).
GCN Circular 18091
Subject
GRB 150728A: Swift-BAT refined analysis
Date
2015-07-28T17:30:34Z (10 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), 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), T. Sakamoto (AGU),
M. Stamatikos (OSU)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+946 sec from the recent telemetry downlinks,
we report further analysis of BAT GRB 150728A (trigger #650617)
(Krimm, et al., GCN Circ. 18087). The BAT ground-calculated position is
RA, Dec = 292.271, 33.906 deg, which is
RA(J2000) = 19h 29m 05.1s
Dec(J2000) = +33d 54' 20.8"
with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted light curve shows a single spike starting at ~T_zero
and ending at ~T+1.5 sec. T90 (15-350 keV) is 0.83 +- 0.23 sec
(estimated error including systematics).
The time-averaged spectrum from T+0.24 to T+1.20 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.02 +- 0.48. The fluence in the 15-150 keV band is 3.3 +- 1.0 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T+0.22 sec in the 15-150 keV band
is 0.5 +- 0.1 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/650617/BA/
GCN Circular 18090
Subject
GRB 150728A: FTN observations
Date
2015-07-28T17:07:38Z (10 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 2-m Faulkes Telescope North began observing Swift GRB 150728A
(Krimm et al. GCN 18087) on July 28, 13:48:25 UT (~57 minutes after
the BAT trigger) with SDSS r and i filters.
we identify an uncatalogued object within XRT error circle
(Beardmore et al. GCN 18088), at the following position:
RA(J2000) = 19:28:54.81
Dec(J2000)= +33:54:58.0
with an uncertainty of 1". The counterpart has the following
magnitudes:
Mid time from Total Exp Filter Magnitude
trigger (min) (s)
-------------------------------------------------
61.8 120x5 r' 21.8 +- 0.3
73.3 120x5 i' 20.7 +- 0.3
-------------------------------------------------
Magnitudes are calibrated against nearby USNOB-1 stars
(R2 and I).
Presently we cannot state anything about possible variability in
the source flux. However, we note that field is quite crowded.
GCN Circular 18088
Subject
GRB 150728A: Enhanced Swift-XRT position
Date
2015-07-28T15:06:58Z (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 1020 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 150728A, 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 = 292.22873, +33.91604 which is equivalent
to:
RA (J2000): 19h 28m 54.89s
Dec (J2000): +33d 54' 57.7"
with an uncertainty of 4.0 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 18087
Subject
GRB 150728A: Swift detection of a GRB
Date
2015-07-28T13:14:33Z (10 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
H. A. Krimm (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC),
A. A. Breeveld (UCL-MSSL), D. N. Burrows (PSU), S. B. Cenko (GSFC),
P. A. Evans (U Leicester), C. Gronwall (PSU),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester),
P. Romano (INAF-IASFPA), T. Sakamoto (AGU),
B. Sbarufatti (INAF-OAB/PSU) and M. H. Siegel (PSU) report on behalf
of the Swift Team:
At 12:51:11 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150728A (trigger=650617). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 292.288, +33.904 which is
RA(J2000) = 19h 29m 09s
Dec(J2000) = +33d 54' 14"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows two weak peaks
with a total duration of about 20 sec. The peak count rate
was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 12:52:21.1 UT, 70.2 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 292.2269, 33.9165 which
is equivalent to:
RA(J2000) = 19h 28m 54.46s
Dec(J2000) = +33d 54' 59.4"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 188 arcseconds from the BAT onboard position, outside 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 consistent with the Galactic value of 2.59
x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White
filter starting 75 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 none of the XRT error circle. 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 0.20.
Burst Advocate for this burst is H. A. Krimm (hans.krimm 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.)