GRB 130612A
GCN Circular 14874
Subject
GRB 130612A: Swift detection of a burst with an optical counterpart
Date
2013-06-12T03:44:00Z (12 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
J. L. Racusin (NASA/GSFC), J. R. Cummings (NASA/UMBC),
N. Gehrels (NASA/GSFC), J. A. Kennea (PSU),
C. B. Markwardt (NASA/GSFC), F. E. Marshall (NASA/GSFC),
C. Pagani (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and
M. H. Siegel (PSU) report on behalf of the Swift Team:
At 03:22:22 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130612A (trigger=557976). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 259.804, +16.706 which is
RA(J2000) = 17h 19m 13s
Dec(J2000) = +16d 42' 21"
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 5 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 03:23:49.1 UT, 87.0 seconds after
the BAT trigger. The position determined from promptly downlinked data
differs significantly from the on-board position, suggesting that the
XRT may have centroided on a cosmic ray; the initial XRT position
notice should be treated with caution. Using promptly downlinked data
we find an uncatalogued X-ray source with an enhanced position: RA, Dec
259.7940, 16.7205 which is equivalent to:
RA(J2000) = 17h 19m 10.55s
Dec(J2000) = +16d 43' 13.9"
with an uncertainty of 2.7 arcseconds (radius, 90% containment). This
location is 62 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 (5.96 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 7.8
(+9.63/-6.58) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 91 seconds with the White filter
starting 94 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 17:19:10.59 = 259.79411
DEC(J2000) = +16:43:11.7 = 16.71991
with a 90%-confidence error radius of about 0.64 arc sec. This position is 2.3
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.80 with a 1-sigma error of about 0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.08.
Burst Advocate for this burst is J. L. Racusin (judith.racusin 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 Circular 14875
Subject
GRB 130612A: Liverpool Telescope Afterglow detection
Date
2013-06-12T03:58:00Z (12 years ago)
From
Andrea Melandri at INAF-OAB <andrea.melandri@brera.inaf.it>
A. Melandri (INAF-OAB), C.G. Mundell (LJMU) and A. Gomboc (U.
Ljubljana) )report:
The 2-m Liverpool Telescope robotically followed up GRB130612A (Swift
trigger 557976, Racusin et al., GCN 14874) ~16 min after the GRB
trigger time observing with SLOAN-gri filters.
The automatic LT-TRAP procedure detected an uncatalogued fading source
candidate at:
RA = 17:19:10.57
Dec = +16:43:11.6 (J2000)
with magnitude R~18.9 mag (vs USNOB1) ~16 min after the burst
trigger. The object is clearly fading in all filters.
Observations and analysis are ongoing.
GCN Circular 14876
Subject
GRB 130612A: PAIRITEL NIR Afterglow Observations
Date
2013-06-12T04:07:12Z (12 years ago)
From
Adam Morgan at U.C. Berkeley <qmorgan@gmail.com>
A. N. Morgan (UC Berkeley) reports:
We observed the field of GRB 130612A (Racusin et al., GCN 14874) with the
1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began at
2013-Jun-12 03h29m25s UT, 6.65 minutes after the Swift Trigger. In
mosaics (consisting of 48 ~8 second images for a total effective exposure
time of 6.3 minutes) taken simultaneously in the J, H, and Ks filters, we
detect the optical afterglow (Racusin et al., GCN 14874; Melandri et al.,
GCN 14875). The preliminary K-band reduction is corrupted. The
observations quoted below began at 3:32 UT, ~9.5 minutes after the Swift
trigger, after an automatic pointing reset by our telescope.
The preliminary photometry yields:
post burst
t_mid (m) exp.(m) filt mag m_err
14.6 6.3 J 17.26 0.12
14.6 6.3 H 16.78 0.15
Observations are ongoing. All magnitudes are given in the Vega system,
calibrated to 2MASS. No correction for Galactic extinction has been made to
the above reported values.
GCN Circular 14877
Subject
GRB 130612A: Skynet/PROMPT detection of the optical afterglow
Date
2013-06-12T04:36:09Z (12 years ago)
From
Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet <atrotter@physics.unc.edu>
A. Trotter, J. Haislip, D. Reichart, A. LaCluyze, T. Berger, M.
Carroll, H. T. Cromartie, R. Egger, A. Foster, C. Foster, N. Frank, K.
Ivarsen, D. James, M. Maples, J. Moore, M. Nysewander, E. Speckhard, P.
Taylor and J. A. Crain report
Skynet observed the Swift XRT localization of the field of GRB 130612A
(Racusin et al., GCN 14874, Swift trigger #557976), beginning at
2013-06-12, 3:23:27 UT (t=70s post-trigger) using three 16" telescopes
of the PROMPT array at Cerro Tololo, Chile. We detect a fading
afterglow in the B, V and I bands at a position (J2000.0)
RA: 17:19:10.6
Dec: 16:43:11.6,
consistent with the detections of Racusin et al. (GCN 14874), Melandri,
Mundell & Gomboc (GCN 14875), and Morgan (GCN 14876).
A preliminary light curve is at:
http://www.skynet.unc.edu/grb/grb130612a.png
Preliminary photometry is calibrated to 5 NOMAD/USNO B1.0 stars in the
field, and magnitudes are in the Vega system.
Skynet observations are ongoing.
[GCN OPS NOTE(12jun13): Per author's request, the typo in JH's name was corrected.]
GCN Circular 14878
Subject
GRB 130612A: NOT optical observations
Date
2013-06-12T04:50:12Z (12 years ago)
From
Dong Xu at DARK/NBI <dong.dark@gmail.com>
P. Jakobsson (U. Iceland), D. Xu (DARK/NBI), D. Malesani (DARK/NBI),
K. Mikkelsen (U. Oslo), N. Aghanim (CNRS & Universite Paris-Sud Orsay)
report on behalf of a larger collaboration:
We observed the optical afterglow of GRB 130612A (Racusin et al., GCN
14874; Melandri et al., GCN 14875) using the 2.5-m Nordic Optical
Telescope (NOT) equipped with the ALFOSC camera. We obtained 4x300s
R-band images with a median time 04:06:09 UT on 12 June 2013 (i.e.
0.73 hr after the burst).
The optical afterglow was clearly detected with R ~ 20.3 mag
calibrated with nearby stars in the USNO B1 catalog.
[GCN OPS NOTE(12jun13): Per author's request, NA was added to the author list.]
GCN Circular 14879
Subject
GRB 130612A: P60 Observations
Date
2013-06-12T04:56:01Z (12 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. B. Cenko (NASA/GSFC) and D. A. Perley report on behalf of a larger
collaboration:
We have imaged the field of the Swift GRB 130612A (Racusin et al., GCN
14874) with the robotic Palomar 60 inch telescope. Observations consist
of individual 120 s frames in the g', r', i', and z' filters beginning at
4:20 UT on 2013 June 12 (58 minutes after the Swift trigger). The
optical afterglow is detected in individual frames in all four
filters. Using several nearby point sources from the USNO-B1 catalog for
reference, we measure a magnitude of R = 20.8 at this time.
GCN Circular 14880
Subject
GRB 130612A: RATIR Optical Observations
Date
2013-06-12T05:11:03Z (12 years ago)
Edited On
2024-11-07T19:38:20Z (7 months 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>
Nat Butler (ASU), Alan M. Watson (UNAM), 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 (UCSC), 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 130612A (Racusin, et al., GCN Circular
14874) 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 2013/06 12.16 to
2013/06 12.20 UTC (0.40 to 1.31 hours after the BAT trigger), obtaining
a total of 0.71 hours exposure in the r' and i' bands.
For a source within the Swift-XRT error circle, in comparison with
USNO-B1 and 2MASS, we obtain the following detections:
r' 21.23 ± 0.07
i' 21.05 ± 0.06
These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.
The position of the source is consistent with the UVOT afterglow
position Racusin, et al., GCN Circular 14874). The afterglow appears to
have faded considerably since the earlier observations reported by
Melandri et al. (GCN Circular 14875), and Jakobsson et al. (GCN Circular
14878).
We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.
GCN Circular 14881
Subject
GRB130612A OSN I-band observations
Date
2013-06-12T05:40:32Z (12 years ago)
From
Juan Carlos Tello at IAA-CSIC <jtello@iaa.es>
J.C.Tello, V. Casanova (IAA-CSIC), J. Gorosabel (UPV-EHU, IAA-CSIC),
A.J.Castro-Tirado, R. Sanchez-Ramirez, M. Jelinek (IAA-CSIC), on behalf of
a larger collaboration report:
We observed the field of GRB130612A (Racusin et al., GCNC 14874) in the
I-band with the 1.5m telescope in Sierra Nevada, Granada, Spain. Combining
33x10s images (for a total 330 seconds of exposure) spanning from 03h38m
(16 minutes after the burst) to 03h55m (with a mean time of 25 minutes
after the burst) we observe the reported afterglow (Melandri et al., GCNC
14875) with a magnitude of I(Vega) ~ 18.7 when compared to the USNO B1.0
catalog.
GCN Circular 14882
Subject
GRB 130612A: VLT/X-shooter redshift
Date
2013-06-12T06:18:45Z (12 years ago)
From
Nial Tanvir at U.Leicester <nrt3@star.le.ac.uk>
N. R. Tanvir (U. Leicester), K. Wiersema (U. Leicester), D. Xu
(DARK/NBI), J. P. U. Fynbo (DARK/NBI) report for a larger
collaboration:
We observed the afterglow of GRB 130612A (Racusin et al. GCN 14874)
with VLT/X-shooter, beginning at 2013-06-12 04:28 UT, about 66 mins
after the burst.
Preliminary analysis of the spectrum reveals absorption lines of FeII
2261, 2374, 2344, 2383, 2600, 2587, 2600, 2607, MnII 2577, MgII
2796/2803 and MgI 2852 at a common redshift of z=2.006. This
is consistent with a break seen in the UVB arm spectrum due to a
damped Lyman-alpha feature at ~3650 A. We therefore propose
this to be the redshift of the GRB.
We thank the staff at Paranal, particularly Christophe Martayan, for
obtaining these observations.
GCN Circular 14883
Subject
GRB 130612A: TAROT La Silla observatory optical observations
Date
2013-06-12T08:53:25Z (12 years ago)
From
Alain Klotz at IRAP-CNRS-OMP <Alain.Klotz@free.fr>
Klotz A. (IRAP-CNRS-OMP), Gendre B. (IRAP-CNRS-OMP),
Boer M., Siellez K., Dereli H., Bardho O. (UNS-CNRS-OCA),
Atteia J.L. (IRAP-CNRS-OMP) report:
We imaged the field of GRB 130612A detected by SWIFT
(trigger 557976) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.
The observations started 34.4s after the GRB trigger
(14.5s after the notice). The elevation of the field increased from
40 degrees above horizon and weather conditions
were excellents.
The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We detect the OT detected by Racusin et al. (GCNC 14874),
Melandri et al. (GCNC 14875). Photometry is done using
NOMAD-1 1067-0303513 (R.A.=259.7905194 Dec=+16.7139250
R=16.9) as reference star.
At the start of the trail t0+34.4s R=16.9
At the end of the trail t0+94.4s R=17.5
Next images are acquired in tracking mode.
The afterglow is visible more than 30
minutes after the burst. One of the last
measurement is:
From t0+1466s to t0+2113s R=19.9
Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.
This message may be cited.
GCN Circular 14884
Subject
GRB 130612A: Enhanced Swift-XRT position
Date
2013-06-12T11:57:53Z (12 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 501 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 130612A, 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 = 259.79393, +16.71971 which is equivalent
to:
RA (J2000): 17h 19m 10.54s
Dec (J2000): +16d 43' 11.0"
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 14885
Subject
GRB 130612A: Zadko observatory - Gingin optical observations
Date
2013-06-12T13:55:06Z (12 years ago)
From
Alain Klotz at IRAP-CNRS-OMP <Alain.Klotz@free.fr>
A. Klotz (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. Coward (UWA),
B. Gendre (IRAP-CNRS-OMP), M. Boer, K. Siellez, H. Dereli ,
O. Bardho (UNS-CNRS-OCA), A. Williams (PO-UWA), R. Martin (PO-UWA)
report:
We imaged the field of GRB 130612A detected by SWIFT
(trigger 557976) with the Zadko robotic telescope (D=100cm)
located at the observatory - Gingin, Australia.
The observations started 9.3h after the GRB trigger.
The elevation of the field increased from
20 degrees above horizon and weather conditions
were good.
We have not detected the OT detected by Racusin et al.
(GCNC 14874), Melandri et al. (GCNC 14875):
From t0+9.3h to t0+10.2h Rlim = 21.2
Magnitudes are not corrected for galactic dust extinction.
This message may be cited.
GCN Circular 14886
Subject
GRB 130612A: Swift-XRT refined Analysis
Date
2013-06-12T15:44:03Z (12 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
G. Stratta (ASDC), P. D'Avanzo (INAF-OAB), M.C. Stroh (PSU), D.N.
Burrows (PSU), J.A. Kennea (PSU), P.A. Evans (U. Leicester), B.P.
Gompertz (U. Leicester), J.P. Osborne (U. Leicester), V. D'Elia (ASDC)
and J.L. Racusin report on behalf of the Swift-XRT team:
We have analysed 11 ks of XRT data for GRB 130612A (Racusin et al. GCN
Circ. 14874), from 74 s to 30.7 ks after the BAT trigger. The data
comprise 233 s in Windowed Timing (WT) mode (the first 9 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 14884).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.96 (+0.09, -0.08).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.19 (+0.28, -0.26). The
best-fitting absorption column is 7.7 (+6.6, -5.5) x 10^21 cm^-2, at a
redshift of 2.006, in addition to the Galactic value of 6.0 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 3.3 x
10^-11 (4.7 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Galactic foreground: 6.0 x 10^20 cm^-2
Intrinsic column: 7.7 (+6.6, -5.5) x 10^21 cm^-2 at z=2.006
Photon index: 2.19 (+0.28, -0.26)
If the light curve continues to decay with a power-law decay index of
0.96, the count rate at T+24 hours will be 1.8 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.1 x
10^-14 (8.7 x 10^-14) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00557976.
This circular is an official product of the Swift-XRT team.
GCN Circular 14887
Subject
GRB 130612A: Swift/UVOT Detection
Date
2013-06-12T17:42:22Z (12 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (MSSL-UCL) and J. L. Racusin (NASA/GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 130612A 94
s after the BAT trigger (Racusin et al., GCN Circ. 14874).
A fading source consistent with the XRT position (Beardmore et al. GCN
Circ. 14884) is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 17:19:10.58 = 259.79408 (deg.)
Dec (J2000) = +16:43:11.9 = 16.71996 (deg.)
with an estimated uncertainty of 0.53 arc sec. (radius, 90% confidence).
Preliminary detections 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 94 185 89 18.97 � 0.07
v 763 7763 549 >20.6
b 688 13692 1307 >21.3
u 664 1655 117 19.68 � 0.24
w1 639 18651 2143 >21.6
m2 614 17743 1406 >21.6
w2 738 7559 549 >21.1
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.08 in the direction of the
burst (Schlegel et al. 1998).
GCN Circular 14889
Subject
GRB 130612A: MITSuME Okayama upper limits
Date
2013-06-12T19:00:02Z (12 years ago)
From
Daisuke Kuroda at OAO/NAOJ <dikuroda@oao.nao.ac.jp>
D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ),
S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto)
and N. Kawai(Tokyo Tech)
report on behalf of MITSuME and OISTER collaboration:
We observed the field of GRB 130612A (Racusin et al., GCNC 14874)
with the optical three color (g', Rc and Ic) CCD camera attached
to the MITSuME 50cm telescope of Okayama Astrophysical Observatory.
The observation started on 2013-06-12 11:27:22 UT (~8.08 h after the burst).
We could not detect the previously reported afterglow
(Racusin et al., GCNC 14874; Melandri et al., GCNC 14875) in all the three bands.
Three sigma upper limits of the OT are listed below.
We used GSC 2.3 catalog for flux calibration.
#T0+[day] MID-UT T-EXP[sec] g' Rc Ic
-----------------------------------------------------
0.43348 13:46:34 7800.0 >20.2 >20.2 >19.4
-----------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
GCN Circular 14890
Subject
GRB 130612A: ISON-NM optical observations
Date
2013-06-12T21:13:30Z (12 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
L. Elenin (KIAM), A. Volnova (IKI), V. Savanevych (KNURE), A.
Bryukhovetskiy (NSFCTC), I. Molotov (KIAM), A. Pozanenko (IKI) report on
behalf of larger GRB follow-up collaboration:
We observed of the field of the Swift GRB 130612A (Racusin et al., GCN
14874) with 0.45-m telescope of ISON-NM observatory starting on June,
12 (UT) 04:06:14. Series of 30 s exposures were obtained in clear
filter. In the combined images we detected afterglow (Racusin et al.,
GCN 14874; Melandri et al., GCN14875) in coordinates (J2000) 17 19 10.63
+16 43 12.0. Preliminary photometry is based on the USNO-B1.0
1067-0299350 star assuming R=18.92.
UT start, T0+ Filter Exposure, OT
mid,d s
2013-06-12T04:06:14 0.0305 none 30*30 20.75 +/- 0.15
2013-06-12T04:29:28 0.0466 none 30*30 21.25 +/- 0.20
GCN Circular 14894
Subject
GRB 130612A: iTelescope T21 optical observations
Date
2013-06-14T02:27:46Z (12 years ago)
From
Veli-Pekka Hentunen at Taurus Hill Obs,A95 <veli-pekka.hentunen@kassiopeia.net>
Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill
Observatory, Varkaus, Finland) report:
We have detected GRB 130612A optical afterglow at iTelescope observatory
T21 (Mayhill, New Mexico) 0.43m/6.8 astrograph and FLI-PL6303E
CCD camera. One unfiltered image with 300 sec exposure time was made.
The afterglow was detected at following position RA 17:19:10.55
and DEC +16:43:11.9
The following magnitude was obtained from the observation using
NOMAD1 1067-0303513 (R=16.900) as the comparison:
Tmid(sec)+T0 Filter Exp. time Mag Mag err.
1133 unfiltered 300 19.19CR 0.39
GCN Circular 14896
Subject
GRB 130612A: Fermi GBM observation
Date
2013-06-14T18:06:06Z (12 years ago)
From
Gerard Fitzpatrick at UCD <gerard.fitzpatrick@ucdconnect.ie>
G. Fitzpatrick (UCD) reports on behalf of the Fermi GBM Team:
At 03:22:23.36 UT on 12 June 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130612A (trigger 392700146/130612141)
which was also detected by the Swift/BAT (Racusin et al., GCN Circ. 14874).
The GBM on-ground location is consistent with the Swift position.
The GBM light curve consists of a single peak
with a duration (T90) of about 5.6 s (50-300 keV).
The time-averaged spectrum from T0-2.6 s to T0+2.3 s is
adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.3 +/- 0.3 and
the cutoff energy, parameterized as Epeak, is 61.9 +/- 10.5 keV.
The event fluence (10-1000 keV) in this time interval is
(5.7 +/- 0.6)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1.8 s in the 10-1000 keV band is 4.1 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog.
GCN Circular 14914
Subject
GRB 130612A: Continued Skynet/PROMPT/GORT/DSO observations
Date
2013-06-17T23:14:09Z (12 years ago)
From
Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet <atrotter@physics.unc.edu>
M. Carroll, A. Trotter, J. Hailslip, D. Reichart, A. LaCluyze, K. McLin,
L. Cominsky, A. Smith, D. Caton, L. Hawkins, T. Berger, H. T. Cromartie,
R. Egger, A. Foster, C. Foster, N. Frank, K. Ivarsen, D. James, M.
Maples, J. Moore, M. Nysewander, E. Speckhard, P. Taylor and J. A. Crain
report
Skynet observed the Swift XRT localization of the field of GRB 130612A
(Racusin et al., GCN 14874, Swift trigger #557976), beginning at
2013-06-12, 3:23:27 UT (t=70s post-trigger), and continuing until t~5h,
using three 16" telescopes of the PROMPT array at Cerro Tololo, Chile
(BVI bands), the 14" GLAST Optical Robotic Telescope (GORT) at the Hume
Observatory in California (RcIc bands), and the 14" telescope at the
Appalachian State University Dark Sky Observatory (DSO-14) in Pisgah
National Forest, North Carolina (RI bands). It took a total of ~500
exposures ranging from 10s to 160s.
As we reported in Trotter et al. (GCN 14877), we detect a fading
afterglow in the B, V and I bands out to t~1h at a position consistent
with the detections of Racusin et al. (GCN 14874), Melandri, Mundell &
Gomboc (GCN 14875), and Morgan (GCN 14876). In stacked images we obtain
further detections in the V band at t=3.2h, and in the I band at t=1.5h
and 1.9h. The afterglow fades with an approximate temporal index
alpha~-0.9.
A preliminary light curve is at:
http://skynet.unc.edu/grb/grb130612a_2.png
Magnitudes are in the Vega system, calibrated to 4 APASS stars in the
field. No correction has been applied for the expected line-of-sight
Milky Way extinction E(B-V)=0.076 (Schlegel et al. 1998).
No further Skynet observations are scheduled.
GCN Circular 14916
Subject
GRB 130612A: Swift-BAT refined analysis
Date
2013-06-19T22:01:54Z (12 years ago)
From
Craig Markwardt at NASA/GSFC <craigm@milkyway.gsfc.nasa.gov>
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), T. Sakamoto (AGU),
on behalf of the Swift-BAT team:
Using the data set from T-25 to T+100 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 130612A (trigger
#557976) (Racusin, et al., GCN Circ. 14874). The BAT ground-calculated
position is
RA, Dec = 259.771, 16.729 deg which is
RA(J2000) = 17h 19m 05.0s
Dec(J2000) = +16d 43' 44.7"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 34%.
The mask weighted light curve shows a single FRED-like profile with a
rise time of about 1 sec near T+0sec and a gradual decay time with
e-folding time of about 3 sec. This burst was detected as the Swift
spacecraft was entering the South Atlantic Anomaly region, and the raw
background counting rate was ramping upward. The mask weighted light
curve does not have a clean background level, so estimating the T90 is
difficult. If we restrict the analysis to the time range T-25 to T+100,
we estimate T90 (15-350 keV) to be 4.0 +/- 1.4 sec. However, we cannot
rule out the possibility of a faint extended emission tail to
approximately T+100 (in which case T90 is 110 +/- 60 sec).
The time-averaged spectrum from T-0.83 to T+3.17 sec is best fit by a
power law with an exponential cutoff. This fit gives a photon index
-0.14 +- 1.71, and Epeak of 36.4 +- 7.6 keV (chi squared 36 for 56
d.o.f.). For this model the total fluence in the 15-150 keV band is 2.3
+- 0.5 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+0.17 sec
in the 15-150 keV band is 1.7 +- 0.3 ph/cm2/sec. A fit to a simple
power law gives a photon index of 2.06 +- 0.25 (chi squared 44 for 57
d.o.f.). 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/557976/BA/