GRB 130420A
GCN Circular 14405
Subject
GRB 130420A: Faulkes Telescope North candidate
Date
2013-04-20T07:46:12Z (12 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
C. Guidorzi (U. Ferrara), A. Melandri (INAF-OAB),
D. Kopac, A. Gomboc (U. Ljubljana), on behalf of a
large collaboration report:
The 2-m Faulkes Telescope North automatically began observing
GRB 130420A at 4.35 minutes from the Swift/BAT trigger time.
The automatic LT-TRAP procedure identified a bright uncatalogued
object at the following position:
RA= 13:04:25.57
Dec= +59:25:26.7
(J2000.0).
Its magnitude is estimated to be 15.9 in the R band.
GCN Circular 14406
Subject
GRB 130420A: Swift detection of a burst with an optical counterpart
Date
2013-04-20T07:50:15Z (12 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
M. J. Page (UCL-MSSL), W. H. Baumgartner (GSFC/UMBC),
A. P. Beardmore (U Leicester), M. M. Chester (PSU),
J. R. Cummings (NASA/UMBC), S. R. Oates (UCL-MSSL) and
D. M. Palmer (LANL) report on behalf of the Swift Team:
At 07:28:29 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130420A (trigger=553977). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 196.100, +59.424 which is
RA(J2000) = 13h 04m 24s
Dec(J2000) = +59d 25' 25"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a very gradual beginning
and a large peak at T+100 seconds. The total duration was about 200 sec.
Because of the gradual beginning, the trigger was an image rather than a rate
trigger. The peak count rate was ~3985 counts/sec (15-350 keV), at ~110 sec
after the trigger.
The XRT began observing the field at 07:40:44.8 UT, 735.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 196.1061, 59.4241 which
is equivalent to:
RA(J2000) = 13h 04m 25.46s
Dec(J2000) = +59d 25' 26.8"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 11 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 consistent with the Galactic value of 1.26
x 10^20 cm^-2 (Kalberla et al. 2005).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 738 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 13:04:25.57 = 196.10654
DEC(J2000) = +59:25:26.9 = 59.42415
with a 90%-confidence error radius of about 0.75 arc sec. This position is 5.1
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.22 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.01.
Burst Advocate for this burst is M. J. Page (m.page AT ucl.ac.uk).
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 14407
Subject
GRB 130420A: ROTSE-III Detection of Optical Counterpart
Date
2013-04-20T08:08:48Z (12 years ago)
From
Tolga Guver at UA <tolga@physics.arizona.edu>
GRB 130420A: ROTSE-III Detection of Optical Counterpart
T. Guver (Sabanci U), report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 130420A (Swift trigger 553977). The first image was at 07:29:51.5 UT, 82.0 s after the burst (7.5 s after the GCN notice time). The unfiltered images are calibrated relative to USNO A2.0. We detect a 15.5 magnitude, fading source with coordinates:
13:04:25.5 +59:25:27.2 (J2000), with positional uncertainty of 1" or better
start UT mag mlim(of image)
----------------------------------
07:34:12.7 15.5 16.5
This source is not visible in DSS (second epoch), 2MASS or the MPChecker database.
A jpeg image is available at http://www.rotse.net/images/gsq553977_3b03_img.jpg Note that the object marked 91 is the candidate in question.
Continuing observations are in progress.
GCN Circular 14408
Subject
GRB 130420A: PAIRITEL NIR detections
Date
2013-04-20T08:16:50Z (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 130420A (Page et al., GCN 14406) with the 1.3m
PAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2013-Apr-20
07h37m23s UT, 8.9 minutes after the Swift Trigger. In mosaics (effective
exposure time of ~10 minutes) taken simultaneously in the J, H, and Ks
filters, we detect the optical afterglow (Guidorzi et al., GCN 14405; Page
et al., GCN 14406; Guver et al., GCN 14407).
The preliminary photometry yields:
post burst
t_mid (hr) exp.(m) filt mag m_err
0.28 9.75 J 15.59 0.05
0.28 9.75 H 14.99 0.07
0.28 9.75 Ks 14.13 0.12
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 14409
Subject
GRB 130420A: RATIR Optical and NIR Observations
Date
2013-04-20T11:56:25Z (12 years ago)
Edited On
2024-11-07T18:53:42Z (7 months 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 (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 130420A (Page, et al., GCN 14406) 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 2013/04 20.41 to 2013/04 20.45 UTC (2.48
to 3.38 hours after the BAT trigger), obtaining a total of 0.36 hours
exposure in the r' and i' bands and 0.14 hours exposure in the Z,
Y, J, and H bands.
For a source within the Swift-XRT error circle, in comparison with SDSS DR8
and 2MASS, we find:
r' 19.81 +/- 0.02
i' 19.41 +/- 0.02
Z 19.37 +/- 0.06
Y 18.99 +/- 0.07
J 19.16 +/- 0.07
H 18.87 +/- 0.11
These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB. Uncertainties are 1-sigma.
Comparison to the earlier photometry of Morgan et al. (GCN 14408) shows that this source has faded by about 2.5 magnitudes in J and H.
We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.
--
Dr. Alan M. Watson
Instituto de Astronomía
Universidad Nacional Autónoma de México
GCN Circular 14410
Subject
GRB 130420A: T21 optical observations
Date
2013-04-20T13:06:20Z (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 130420A optical afterglow at iTelescope
Observatory T21 (Mayhill, New Mexico) 0.43-m/6.8 astrograph
and FLI ProLine PL6303E CCD. Two unfiltered images with 600
sec exposure time were made.
The afterglow was detected at following position RA 13:04:25.51
and DEC +59:25:27.2.
The following magnitudes were obtained from the observations using
NOMAD1 1494-0215473 (R=16.220) as the comparison:
Tmid(sec)+T0 Filter Exp. time Mag Mag err. Limit
7258 unfiltered 600 19.49CR 0.20 20.60
7885 unfiltered 600 19.61CR 0.24 20.48
GCN Circular 14413
Subject
GRB 130420A: Weihai Optical Observations
Date
2013-04-20T13:57:41Z (12 years ago)
From
Dong Xu at DARK/NBI <dong.dark@gmail.com>
D. Xu (DARK/NBI), C. Cao, S.M. Hu (SDU) report:
We observed the field of GRB 130420A (Page et al., GCN 14406) using
the 1m telescope located in Weihai, Shandong Province, China.
Observations started at 11:41:32 UT, 2013-04-20 (i.e., 4.218 hr after
the BAT trigger) and 12x180s I-band frames were obtained.
The optical afterglow (Page et al., GCN 14406) is clearly detected in
our stacked image to be of I=19.4 mag, calibrated with nearby USNO B1
stars. It has decayed by about 0.5 mag, compared to the measurement in
Watson et al. (GCN 14409).
We thank Dayong Ren for carrying out these observations.
GCN Circular 14415
Subject
GRB130420A : Xinglong TNT optical upper limit
Date
2013-04-20T15:59:58Z (12 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
L.P. Xin, M. Zhai, J. Y. Wei, Y. L. Qiu, J. Wang,
J. S. Deng, C. Wu, X.H. Han report on behalf of EAFON team:
We began to observe the field of GRB 130420A (Page et al., GCN 14406 )
using 80cm TNT telescope located at Xinglong observatory, China
at 12:16:56 UT on 2013-04-20. We obtained 12x300s R-band images in a
poor seeing and cloudy weather, with a median time of 5.3 hr after the BAT trigger.
The afterglow reported (Page et a., GCN 14406 ) is not detected in the stacked image,
down to a 3 sigma limit of R~18.0 mag, calibrated with USNO B2 stars.
This message may be cited.
GCN Circular 14416
Subject
GRB 130420A: Enhanced Swift-XRT position
Date
2013-04-20T17:34:00Z (12 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 2151 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 130420A, 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 = 196.10626, +59.42406 which is equivalent
to:
RA (J2000): 13h 04m 25.50s
Dec (J2000): +59d 25' 26.6"
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 14418
Subject
GRB 130420A: GMG optical observation
Date
2013-04-20T18:49:21Z (12 years ago)
From
Xiao-hong Zhao at Yunnan Obs <zhaoxiaohong78@gmail.com>
X.-H. Zhao (YNAO and PSU), J. Mao (RIKEN and YNAO), J.-M. Bai
(YNAO) report on behalf of a larger collaboration:
We observed the field of GRB 130420A (Page et al., GCN 14406) with 2.4m Gao-Mei-Gu (GMG) telescope. Observations
started at 13:36:00 UT on 2013-04-20 (i.e., 6.13 hrs after the burst, ~2 hrs later than the observation of Xu et al., GCN 14413) and 3x600s R-band and 1x600s I-band images were obtained. The optical counterpart of this burst was detected in both bands. The mag are R~19.4 and I~20.2 calibrated with USNO B1 stars.
We thank the GMG staff, especially Yu-Xin Xin, Gui-Hua He and Jian-Duo He for
performing these observations.
GCN Circular 14419
Subject
GRB 130420A, Swift-BAT refined analysis
Date
2013-04-20T19:33:42Z (12 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <james.r.cummings@nasa.gov>
GRB 130420A, Swift-BAT refined analysis
A. Y. Lien (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), M. J. Page (UCL-MSSL),
D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+303 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 130420A (trigger #553977)
(Page et al., GCN 14406). The BAT ground-calculated position is
RA, Dec = 196.118, 59.421 deg which is
RA(J2000) = 13h 04m 28.3s
Dec(J2000) = +59d 25' 16.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 86%.
The mask-weighted light curve shows a precursor beginning gradually at about
T-20 seconds and increasing irregularly to about T+100 seconds. The main
emission had a FRED shape peaking at about T+110 seconds that was detectable
until about T+200 seconds. T90 (15-350 keV) is 123.5 +- 13.1 sec (estimated
error including systematics).
The time-averaged spectrum from T-19.7 to T+189.9 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.52 +- 0.25,
and Epeak of 33.2 +- 6.8 keV (chi squared 42.40 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 7.1 +- 0.3 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+110.67 sec in the 15-150 keV band is
3.4 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index
of 2.18 +- 0.05 (chi squared 66.06 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/553977/BA/
GCN Circular 14422
Subject
GRB 130420A: Swift-XRT refined Analysis
Date
2013-04-20T19:50:05Z (12 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
A. Maselli (INAF-IASFPA), V. Mangano (INAF-IASFPA), 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), A. Melandri
(INAF-OAB) and M.J. Page report on behalf of the Swift-XRT team:
We have analysed 7.9 ks of XRT data for GRB 130420A (Page et al. GCN
Circ. 14406), from 742 s to 19.7 ks after the BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Goad et al. (GCN. Circ 14416).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.81 (+/-0.05).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.29 (+0.14, -0.13). The
best-fitting absorption column is 7.1 (+2.5, -2.4) x 10^20 cm^-2, in
excess of the Galactic value of 1.3 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 3.1 x 10^-11 (4.1 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 7.1 (+2.5, -2.4) x 10^20 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: 4.1 sigma
Photon index: 2.29 (+0.14, -0.13)
If the light curve continues to decay with a power-law decay index of
0.81, 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 6.5 x
10^-13 (8.5 x 10^-13) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00553977.
This circular is an official product of the Swift-XRT team.
GCN Circular 14424
Subject
GRB 130420A: Swift/UVOT Detection
Date
2013-04-20T21:06:26Z (12 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates, M. De Pasquale, and M. J. Page (UCL-MSSL)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 130420A
739 s after the BAT trigger (Page et al., GCN Circ. 14406).
A source consistent with the XRT position
(Goad et al. GCN Circ. 14416) is detected in the initial UVOT exposures.
The GRB is detected in all filters and is therefore consistent with
being at a redshift of ~<1.6.
The preliminary UVOT position is:
RA (J2000) = 13:04:25.55 = 196.10647 (deg.)
Dec (J2000) = +59:25:27.1 = 59.42420 (deg.)
with an estimated uncertainty of 0.50 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 739 888 147 17.14 +/- 0.03
v 1072 1092 20 17.66 +/- 0.31
b 1171 1191 19 18.13 +/- 0.21
u 1146 1166 20 17.19 +/- 0.17
w1 1122 1141 19 17.51 +/- 0.29
m2 1097 1465 58 18.30 +/- 0.31
w2 1049 1240 39 18.50 +/- 0.33
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 14427
Subject
Skynet/GORT observations of GRB130420A
Date
2013-04-20T22:28:05Z (12 years ago)
From
Adam S. Trotter at UNC-Chapel Hill/NC AnTPROMPT/Skynet <atrotter@physics.unc.edu>
A. Trotter, N. Frank, A. LaCluyze, D. Reichart, K. McLin, L. Cominsky,
T. Berger, J. A. Crain, H. T. Cromartie, R. Egger, A. Foster, J.
Haislip, K. Ivarsen, M. Maples, J. Moore, M. Nysewander, and E.
Speckhard report:
Skynet observed the Swift/BAT localization of GRB 130420A (Page et al.,
GCN 14406, Swift trigger 553977) with the 14" GLAST Optical Robotic
Telescope (GORT) at the Hume observatory in California, beginning ~100s
after the trigger in RcIc, and continuing until the source set at
t=4.9h. We detect the afterglow reported by Guidorzi et al. (GCN 14405)
at RA 13:04:06.6, Dec +59:25:25.2 (J2000), within the error circle
reported by the Swift XRT (GCN 14406). Photometry was calibrated to six
SDSS stars in the field.
The afterglow exhibits a rising light curve in both Rc and Ic bands at
early times, peaking at t=330s (peak Rc~16, Ic~15.5), after which it
fades with an approximate temporal index alpha~-1. There is some
evidence for flattening of the Ic-band light curve at t>1h, at which
time Ic~18.7.
Follow-up observations at GORT have been scheduled.
A preliminary light curve of the first night's data can be found at:
http://skynet.unc.edu/grb/grb130420a.png
GCN Circular 14428
Subject
GRB 130420A: ISON-NM optical observations
Date
2013-04-21T03:58:45Z (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 the field of the Swift GRB 130420A (Page et al., GCN 14406)
with 0.45-m telescope of ISON-NM observatory on Apr. 20, between (UT)
07:30:54 - 10:51:49. The observation started automatically 144 s after
burst trigger. We took several unfiltered images of 30, 60 and 300 s
exposures. The optical counterpart of GRB 130418A (Guidorzi et al., GCN
14405; Page et al., GCN 14406; Guver et al., GCN 14407) is clearly visible
in single images.
Coordinates of the counterpart are (J2000) RA = 13:04:25.56 Dec =
+59:25:26.8 with uncertainties of 0.2" coincide with the coordinates
reported early (Guidorzi et al., GCN 14405, Guver et al., GCN 14407).
A photometry of single and later combined image is based on the SDSS stars
with assumed R-magnitude
J130421.49+592547.6 R = 16.13
J130416.49+592509.2 R = 16.95
J130443.88+592659.3 R = 14.54
Preliminary light curve can be found at
http://grb.rssi.ru/GRB130420A/GRB130420A_lightcurve_ISON-NM.png
The light curve is clearly exhibit a fast rise and peaked with 16.1 mag at
~0.0207days after burst trigger following steep power law decay and later at
0.05 days swallowing to the typical afterglow power law.
GCN Circular 14429
Subject
GRB 130420A: Fermi GBM observation
Date
2013-04-21T04:44:55Z (12 years ago)
From
Shaolin Xiong at UAH <sx0002@uah.edu>
Shaolin Xiong (UAH) and Arne Rau (MPE)
report on behalf of the Fermi GBM Team:
"At 07:30:19.92 UT on 20 April 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130420A (trigger 388135822 / 130420313),
which was also detected by the Swift (Page et al. 2013, GCN 14406).
The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 134 degrees.
The GBM light curve consists of precursors and a bright peak
with a duration (T90) of about 102 s (50-300 keV).
The time-averaged spectrum from T0-10 s to T0+27 s is
adequately fit by a power law function with an exponential
high-energy cutoff. The power law index is 1.00 +/- 0.13 and
the cutoff energy, parameterized as Epeak, is 56 +/- 3 keV.
The event fluence (10-1000 keV) in this time interval is
(1.4 +/- 0.05)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.0 s in the 10-1000 keV band
is 5.2 +/- 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 14431
Subject
GRB 130420A: Continued RATIR Optical and NIR Observations
Date
2013-04-21T16:54:47Z (12 years ago)
Edited On
2024-11-07T19:55:28Z (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 again observed the field of GRB 130420A (Page et al., GCN 14406) 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 2013/04 21.30 to 2013/04 21.47UTC (23.66 to 27.79 hours after the BAT trigger), obtaining a total of 1.44 hours exposure in the r' and i' bands and 0.59 hours exposure in the Z, Y, J, and H bands.
The afterglow is well-detected. In comparison with SDSS DR8 and 2MASS, we obtain:
r' 22.11 +/- 0.08
i' 21.90 +/- 0.09
Z 21.52 +/- 0.18
Y 21.40 +/- 0.31
J 21.24 +/- 0.26
H 20.38 +/- 0.23
These magnitudes are in the AB system, quoted with 1-sigma uncertainty, and not corrected for Galactic extinction in the direction of the GRB. In comparison with our observations on the previous night (Watson et al., GCN 14409), the afterglow has faded by more than about 2 magnitudes in all bands.
We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.
GCN Circular 14436
Subject
GRB 130420A: Early RAPTOR Simultaneous Multi-Color Observations
Date
2013-04-22T17:34:49Z (12 years ago)
From
James Wren at LANL <jwren@nis.lanl.gov>
J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis,
of Los Alamos National Laboratory report:
The RAPTOR network of robotic optical telescopes made follow-up observations
of Swift trigger 553977 (Page, et al., GCN 14406). Our RAPTOR-S and RAPTOR-T
robotic telescopes located in Los Alamos, NM, began imaging at 07:29:52.95 UTC,
83.4 s after the Swift BAT trigger and continued during the entire period the
BAT was detecting the dominant gamma-ray pulse (Lien, et al., GCN 14419). We
detect optical emission during the gamma-ray emitting interval at the location
of the counterpart reported by the Faulkes team (Guidorzi, et al., GCN 14405).
In subsequent images we see a rapid rise in brightness at the same location,
peaking at about T+300s. These observations were made simultaneously using
SDSS g', r', i', z' and clear filters. Our unfiltered observations are
consistent with the lightcurve published by the ISON team (Elenin, et al.,
GCN 14428).
GCN Circular 14437
Subject
GRB 130420A: Redshift from 10.4m GTC
Date
2013-04-22T18:33:44Z (12 years ago)
From
Antonio de Ugarte Postigo at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), N. Tanvir (U. Leicester),
R. Sanchez-Ramirez (IAA-CSIC), C.C. Thoene (IAA-CSIC),
J. Gorosabel (UPV/EHU, IAA-CSIC), and J. P. U. Fynbo (DARK/NBI) report:
We obtained spectroscopy of the afterglow of GRB 130420A (Page
et al. GCN 14406) with the 10.4m GTC telescope on the 22nd April 2013,
starting at 03:42 UT (1.84 days after the burst). The observation consisted of
4x900 s using the R500B grating, with a resolution of R~500 in the range 3600
- 8700 A.
The spectrum shows an emission line that we identify as [OII] from the host
and several absorption features that correspond to MgII, MgI, FeII and AlIII at
a common redshift of 1.297, which we identify as the redshift of the GRB.
We also note the presence of an unrelated nearby galaxy (at an angular
separation of 2.5") which shows emission lines of [OII], H-beta and [OIII] at a
redshift of 0.584.
We acknowledge the excellent support of the GTC staff.
GCN Circular 14439
Subject
GRB 130420A: Continued RATIR Optical and NIR Observations
Date
2013-04-22T21:22:43Z (12 years ago)
Edited On
2024-11-07T19:55:14Z (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>
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 (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 again observed the field of GRB 130420A (Page et al., GCN Circular
14406) 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 2013/04 22.35 to
2013/04 22.47 UTC (48.84 to 51.69 hours after the BAT trigger),
obtaining a total of 0.71 hours exposure in the r' and i' bands and 0.29
hours exposure in the Z, Y, J, and H bands.
The afterglow is again detected in several bands. In comparison with
SDSS DR8 and 2MASS, we obtain:
r' 22.63 +/- 0.17
i' 22.46 +/- 0.17
Z 21.62 +/- 0.25
Y > 21.32
J > 21.39
H > 20.91
These magnitudes are in the AB system, quoted with 1-sigma uncertainty,
and not corrected for Galactic extinction in the direction of the GRB.
The upper limits are at the 3-sigma level.
In comparison with our earlier observations (Watson et al., GCN Circular
14409; Butler et al., GCN Circular 14431), we see that the afterglow
faded by about 2 magnitudes from about 3 to about 25 hours after the
Swift trigger, but then by only about another 0.5 magnitudes from about
25 to about 50 hours after the Swift trigger.
We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.
GCN Circular 14440
Subject
GRB 130420A: ROTSE-III data analysis
Date
2013-04-24T21:13:55Z (12 years ago)
From
Farley V. Ferrante at Southern Methodist U/ROTSE <fferrante@smu.edu>
F. V. Ferrante (SMU), G. Dhungana (SMU), T. Guver (Sabanci U), W. Zheng (UC Berkeley), H. Flewelling (IfA/Hawaii), F. Yuan (Australian National University), and R. Kehoe (SMU) report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 130420A (Swift trigger 553977; Guidorzi et al., GCN 14405; Page et al., GCN 14406; Guver et al., GCN 14407). The first image was at 07:29:51.5 UT, 82.0 s after the burst (7.5 s after the GCN notice time). We continued to monitor the source reported in GCN 14405, 14406, and 14407. The unfiltered images are calibrated relative to USNO A2.0. We took 220 20-sec exposures and observed a maximum magnitude of 15.5.
Further analysis of ROTSE-IIIb data using RPHOT indicates that the afterglow of GRB 130420A displays a single power-law decay with index alpha = - 0.70 up to ~1500 s after the burst. After the power law fall-off, the afterglow continued to be detected in subsequent images for ~6 ks. The minimum observed magnitude was 17.5.
GCN Circular 14441
Subject
GRB 130420A: Continued RATIR Optical and NIR Observations
Date
2013-04-25T01:25:12Z (12 years ago)
Edited On
2024-11-07T18:57:03Z (7 months 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>
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 again observed the field of GRB 130420A (Page et al., GCN Circular
14406) 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 2013/04 24.26 to
2013/04 24.46 UTC (94.73 to 99.64 hours after the BAT trigger),
obtaining a total of 2.84 hours exposure in the r' and i' bands and 1.19
hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT error circle, in comparison with SDSS
DR8 and 2MASS, we obtain the following upper limits (3-sigma) in the AB
magnitude system:
r' > 23.15
i' > 23.02
Z > 21.75
Y > 21.44
J > 21.72
H > 21.16
These magnitudes are not corrected for Galactic extinction in the
direction of the GRB.
In comparison with our earlier observations (Watson et al., GCN Circular
14409; Butler et al., GCN Circular 14431; Watson et al., GCN Circular
14439), the source has faded by about at least a magnitude in r' and i'
between about 50 and about 97 hours.
We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.
GCN Circular 14445
Subject
GRB 130420A: Continued Skynet/GORT Observations/Detections
Date
2013-04-25T22:19:25Z (12 years ago)
From
Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet <atrotter@physics.unc.edu>
A. Trotter, N. Frank, A. LaCluyze, D. Reichart, K. McLin, L. Cominsky,
T. Berger, H. T. Cromartie, R. Egger, A. Foster, J. Haislip, K. Ivarsen,
M. Maples, J. Moore, M. Nysewander, E. Speckhard, and J. A. Crain report:
Skynet continued observing the field of GRB 130420A (Page et al., GCN
14406, Swift trigger #553977) with the 14" GLAST Optical Robotic
Telescope (GORT) at the Hume Observatory in California. It took 214 80-s
exposures in Ic at times t=20.48-23.30h and t=26.25-28.56h after burst
trigger, and 96 80-s exposures in Rc at t=23.33-26.15h. We performed
photometry on the stacked exposures in each band, calibrated to six SDSS
stars in the field. We detect the afterglow in both Ic and Rc bands at
t~24h:
band exp length mean time since trig mag(Vega)
Ic 4.76h 24.37h 21.04 (+0.43,-0.31)
Rc 2.47h 24.77h 21.00 (+0.25,-0.21)
As we note in Trotter et al. (GCN 14427), and as Elenin et al. (GCN
14428) confirm, the afterglow exhibits a rising light curve at early
times, peaking at t=330s (peak Rc~16, Ic~15.5). After the peak, the
light curve fades with a power law index alpha~-0.9.
A preliminary light curve of the first and second nights' data is at:
http://skynet.unc.edu/grb/grb130420a_2.png