GRB 120722A
GCN Circular 13499
Subject
GRB 120722A: Swift detection of a burst
Date
2012-07-22T13:05:44Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
A. Melandri (INAF-OAB), S. D. Barthelmy (GSFC),
P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC),
J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU) and
E. Sonbas (NASA/GSFC/Adiyaman Univ.) report on behalf of the Swift
Team:
At 12:53:26 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 120722A (trigger=528195). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 230.491, +13.250 which is
RA(J2000) = 15h 21m 58s
Dec(J2000) = +13d 15' 01"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a peak with a total
duration of about 25 sec. The peak count rate
was ~1300 counts/sec (15-350 keV), at ~5 sec after the trigger.
The XRT began observing the field at 12:55:59.4 UT, 153.0 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 230.49665, 13.25112 which is equivalent
to:
RA(J2000) = 15h 21m 59.20s
Dec(J2000) = +13d 15' 04.0"
with an uncertainty of 4.1 arcseconds (radius, 90% containment). This
location is 20 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 does not constrain the column density.
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 156 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
0.05.
Burst Advocate for this burst is A. Melandri (andrea.melandri 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 Circular 13500
Subject
GRB 120722A: Xinglong TNT optical afterglow candidate
Date
2012-07-22T14:18:45Z (13 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
L. P. Xin, J. Y. Wei, Y. L. Qiu, J. Wang, J. S. Deng,
C. Wu, X. H. Han on behalf of EAFON report:
We began to observe GRB 120722A (Melandri et al. GCN 13499)
with Xinglong TNT telescope in R-band at 12:56:53 (UT),
3.5 min after the burst. An optical counterpart was detected
in our combined image within the errorbox of X-ray afterglow location
(Melandri et al. GCN 13499) with a brightness of about 20.8 mag in R band,
calibrated against the USNO B1.0 R2mag.
The coordinates and magnitude of the reference star we used
are 15:21:54.116 +13:15:50.70, J2000 and R2=16.91 mag in USNO B1.0.
This message may be cited.
Further observations are encouraged.
For more information about Xinglong GRBs Follow-up
observations, please visit the website:
http://www.xinglong-naoc.org:8080/grb/index.html
We thank Chunlan Lu for performing these observations.
GCN Circular 13501
Subject
GRB 120722A: Correction for GCN circ.13500
Date
2012-07-22T16:43:59Z (13 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
L. P. Xin, J. Y. Wei, Y. L. Qiu, J. Wang, J. S. Deng,
C. Wu, X. H. Han on behalf of EAFON report:
We apologize for the wrong result reported in GCN circ. 13500 .
Caused by a wrong astronomical calibration,
the optical candidate of GRB 120722A reported in GCN circ. 13500
should be a known object in the USNO B1.0
Therefore, no any new source within the location of
XRT counterpart was detected by TNT. The 3 sigma upper limit
of 21 mag was derived relatively to USNO B1.0 R2 mag.
GCN Circular 13502
Subject
GRB 120722A: Enhanced Swift-XRT position
Date
2012-07-22T17:58:21Z (13 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1220 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 120722A, 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 = 230.49656, +13.25109 which is equivalent
to:
RA (J2000): 15h 21m 59.17s
Dec (J2000): +13d 15' 03.9"
with an uncertainty of 2.1 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 13503
Subject
GRB 120722A: Swift-BAT refined analysis
Date
2012-07-22T22:40:29Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), A. Melandri (INAF-OAB), D. M. Palmer (LANL),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 120722A (trigger #528195)
(Melandri, et al., GCN Circ. 13499). The BAT ground-calculated position is
RA, Dec = 230.489, 13.249 deg, which is
RA(J2000) = 15h 21m 57.4s
Dec(J2000) = +13d 14' 56.8"
with an uncertainty of 3.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 19%.
The mask-weighted light curve shows a couple overlapping peaks starting
at ~T-10 sec, peaking at ~T+23 sec, and ending at ~T+50 sec.
T90 (15-350 keV) is 42.4 +- 10.5 sec (estimated error including systematics).
The time-averaged spectrum from T-0.3 to T+47.5 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.90 +- 0.25. The fluence in the 15-150 keV band is 1.2 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+24.02 sec in the 15-150 keV band
is 1.0 +- 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/528195/BA/
GCN Circular 13504
Subject
GRB 120722A: Swift-XRT refined Analysis
Date
2012-07-23T01:05:03Z (13 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
C. Pagani (U. Leicester), G. Stratta (ASDC), P. D'Avanzo (INAF-OAB), V.
D'Elia (ASDC), D.N. Burrows (PSU), J.A. Kennea (PSU), M.C. Stroh (PSU),
A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and A.
Melandri report on behalf of the Swift-XRT team:
We have analysed 8.4 ks of XRT data for GRB 120722A (Melandri et al.
GCN Circ. 13499), from 161 s to 27.7 ks after the BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Evans et al. (GCN. Circ 13502).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.85 (+0.12, -0.11).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.6 (+0.8, -0.7). The
best-fitting absorption column is 5.1 (+1.8, -1.5) x 10^22 cm^-2, in
excess of the Galactic value of 3.1 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 8.4 x 10^-11 (5.7 x 10^-10) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 5.1 (+1.8, -1.5) x 10^22 cm^-2
Galactic foreground: 3.1 x 10^20 cm^-2
Excess significance: 5.6 sigma
Photon index: 2.6 (+0.8, -0.7)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00528195.
This circular is an official product of the Swift-XRT team.
GCN Circular 13505
Subject
GRB 120722A: 1.5m OSN I-band observations
Date
2012-07-23T02:37:11Z (13 years ago)
From
Javier Gorosabel at IAA-CSIC <jgu@iaa.es>
F. Aceituno (OSN, IAA-CSIC), R. Sanchez-Ramirez (IAA-CSIC), A. de Ugarte
Postigo (IAA-CSIC, DARK), J. Gorosabel (IAA-CSIC), A.J. Castro-Tirado
(IAA-CSIC), report on behalf of a larger collaboration:
"We observed the field of the GRB 120722A XRT error circle (Melandri et
al., GCN 13499; Evans et al., GCN 13502) with the 1.5m telescope at the
Observatorio de Sierra Nevada, Granada, Spain. The observations were
conducted in the I-band with a total exposure time of 16x300s on July
22.86617-22.92716 UT (7.9--9.4 hours post GRB). No object is detected
inside the XRT error circle down to I~21 (Vega mag, calibrated against
USNO-B1.0). We note the presence of a faint object close to the XRT error
circle border located at RA(J2000)=15:21:59.19, Dec(J2000)=+13:15:05.0
(+/-0.9") which seems also present at the SDSS."
GCN Circular 13506
Subject
GRB 120722A: GROND detection of the afterglow
Date
2012-07-23T02:43:22Z (13 years ago)
From
Vladimir Sudilovsky at MPE <vsudilov@mpe.mpg.de>
V. Sudilovsky (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 120722A (Swift trigger 528195; Melandri et
al., GCN #13499) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla
Observatory (Chile).
Observations started at 23:20 UT on 2012-07-22, 10.5 hrs after the GRB
trigger. They were performed at an average seeing of 1.1" arcsec and at an
average airmass of 1.4.
Inside the 2.1 arcsecond XRT error circle (Evans et al., GCN #13502), we
detect a fading source in g'r'i'z' at coordinates RA,DEC (J2000) =
230.4966, 13.2513 = 15:21:59.184, +13:15:04.68 (+/- 0.3 arcsec).
Based on exposures of 1600 seconds in g'r'i'z' and 1200 seconds in JHK,
we measure the following preliminary magnitudes (all in the AB system)
g' = 23.8 +- 0.1,
r' = 23.6 +- 0.1,
i' = 22.8 +- 0.1,
z' = 22.6 +- 0.1,
J > 21.8,
H > 21.2,
K > 19.8.
The power-law like SED and fading nature of this source confirm that it
is the afterglow of GRB 120722A.
All magnitudes are calibrated against SDSS (g'r'i'z') and 2MASS field
stars.
The magnitudes have not been corrected for the Galactic reddening of
E(B-V)=0.05 mag along the line of
sight towards the source (Schlegel et al. 1998).
GCN Circular 13507
Subject
GRB 120722A: VLT/X-shooter redshift of the host galaxy
Date
2012-07-23T07:24:14Z (13 years ago)
From
Valerio D'Elia at ASDC <delia@asdc.asi.it>
V. D'Elia (ASDC/INAF-OAR), D. Xu (WIS), A. de Ugarte Postigo (IAA-CSIC, DARK),
D. Malesani (DARK/NBI), , J. P. U. Fynbo (DARK/NBI), P. Goldoni (APC,CEA/Irfu),
N. R. Tanvir (U. of Leicester) and T. Kruehler (DARK/NBI)
report on behalf of the GRB/X-shooter collaboration
We imaged the field of GRB 120722A (Melandri et al., GCN
13499) with the ESO VLT equipped with the
X-shooter spectrograph. Observations started on 2012 July 22 at 23:08 UT
(10 hr after the GRB), for a total exposure time of 80 min in each of
the UVB, VIS, and NIR arms, covering the wavelength range 3000-25000 AA.
Within the XRT error circle we noted a SDSS object, which is coincident
with the position of the afterglow reported by Sudilovsky et al. (GCN 13506).
The slit was positioned on this object. The object reported by Sudilovsky et al. (GCN 13506)
is faintly detected in a combined stack of the ugriz SDSS data, suggesting a significant host contribution.
The object is also well detected in our R-band acquisition images.
The spectrum is dominated by several nebular emission lines from the candidate host galaxy,
including [O II], [O III] and Balmer lines (Halpha, Hbeta and Hgamma),
at a common redshift z = 0.9586. Given the superposition with
the optical afterglow reported by Sudilovsky et al. (GCN 13506), this is likely the
host galaxy of GRB120722A.
We acknowledge excellent support from the ESO staff, in particular Lorenzo Monaco,
Lorena Faundez and Emanuela Pompei.
GCN Circular 13508
Subject
GRB 120722A: Swift/UVOT Upper Limits
Date
2012-07-23T16:33:17Z (13 years ago)
From
Tyler Pritchard at PSU <tapritchard@astro.psu.edu>
T. A. Pritchard (PSU) and A. Melandri (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 120722A
157 s after the BAT trigger (Melandri et al., GCN Circ. 13499).
No optical afterglow consistent with the Enhanced Swift-XRT position
(Evans et al., GCN Circ. 13502)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 157 307 147 >20.9
u_FC 315 565 246 >20.2
white 157 7159 685 >21.7
v 646 11696 1356 >20.5
b 570 18708 758 >21.4
u 315 18411 1583 >21.6
w1 696 16188 820 >21.3
m2 4785 12602 1279 >21.1
w2 1028 6012 216 >20.2
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 13521
Subject
GRB 120722A: optical upper limit
Date
2012-07-27T15:28:21Z (13 years ago)
From
Alina Volnova at SAI MSU <alinusss@gmail.com>
A. Volnova (SAI MSU, IKI), A. Ivanov, V. Ivanov, V. Lysenko (Kuban
State University), A. Pozanenko (IKI)
We observed the field of the Swift GRB 120422A (Troja et al., GCN
13243) with 20-inch telescope C40 of Kuban State University
Astrophysical Observatory on April 22 between (UT) 18:51:21 - 21:54:56
under mean FWHM of about 3.5 arcsec. We took two series of 30 s and 60
s exposures using R filter. In a stacked image we do not detect any
source in the enhanced XRT error circle (Evans et al., GCN 13502). A
preliminary photometry is based on the nearby USNO-B1.0 stars:
T0+ Filter, Exposure, OT, uplim (3 sigma)
(mid, d) (s)
0.28316 R 60*30s + 31*60s n/d 21.2