GRB 100418A
GCN Circular 10883
Subject
GRB 100418A: late time optical observations
Date
2010-06-25T16:45:00Z (15 years ago)
From
Vasilij Rumjantsev at CrAO <rum@crao.crimea.ua>
V. Rumyantsev (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB
follow-up collaboration:
We observed the field of the Swift GRB 100418A (Marshall et al. GCN
10612) with Shajn telescope of CrAO between (UT) June, 11 20:07 --
21:50 under photometric weather conditions and mean seeing of about 2
arcsec. The preliminary photometry of the afterglow+host in a stacked
image based on USNO-B1.0 star 1014-0271368 (RA(J2000) = 17:05:26.42
Dec(J2000)= +11:27:32.9) assuming R=17.32 is following:
T0+ Filter, Exposure, mag.
(mid, d) (s)
53.9919 R 88x60 22.05 +/-0.07
The brightness of the host is less but compatible with early reported
magnitudes on May 14 (R = 21.86 +/-0.06; GCN 10783) and (Rc = 21.90
+/-0.03; GCN 10794)
GCN Circular 10832
Subject
Radio detection of GRB100418a with ATCA
Date
2010-06-07T14:41:27Z (15 years ago)
From
Aquib Moin at CIRA/ATNF <aquib.moin@postgrad.curtin.edu.au>
Aquib Moin (Curtin Institute of Radio Astronomy / International Centre for Radio Astronomy Research / CSIRO Astronomy and Space Science)
Steven Tingay (Curtin Institute of Radio Astronomy / International Centre for Radio Astronomy Research)
Chris Phillips (CSIRO Astronomy and Space Science)
Gregory Taylor (University of New Mexico)
Mark Wieringa (CSIRO Astronomy and Space Science)
Ralph Martin (Perth Observatory) report:
We observed the field of Swift GRB100418a (GCN 10612, GCN 10614, GCN 10616) at 5.5 GHz and 9.0 GHz with the Australia Telescope Compact Array (ATCA) between 12:30:00 UT and 19:30:00 UT on May 26, 2010.
We clearly detected the radio afterglow at the optical afterglow position of the GRB 100418a (GCN 10616) at both frequencies with flux densities 0.91 +/- 0.04 mJy and 1.46 +/- 0.07 mJy respectively.
Further observations are planned.
The Australia Telescope Compact Array (/ Parkes telescope / Mopra telescope / Long Baseline Array) is part of the Australia Telescope which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.
See the GRB 100418a field images:
http://cira.ivec.org/dokuwiki/doku.php/grb/grb100418a
GCN Circular 10821
Subject
GRB 100418A: Maidanak optical observations
Date
2010-06-01T20:31:58Z (15 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
A. Volnova (SAI MSU), M. Ibrahimov, R. Karimov (MAO), A. Pozanenko (IKI)
report on behalf of larger GRB follow-up collaboration:
We observed the field of the Swift GRB 100418A (Marshall et al. GCN 10612)
with AZT-22 telescope of Maidanak observatory on (UT) Apr. 22 (22:34 --
23:35) and May 7 (22:49 -- 23:27). The optical afterglow (Marshall et al.
GCN 10612, Filgas et al. GCN 10617) is detected in single images on Apr. 22
and in a stacked image on May 7. The photometry of the afterglow based on
USNO-B1.0 star 1014-0271368 (RA(J2000) = 17:05:26.42 Dec(J2000)=
+11:27:32.9) assuming R=17.32 is following:
T0+ Filter, Exposure, seeing, mag.
(mid, d) (s)
4.0793 R 11x300 0.7 20.56 +/- 0.02
19.0821 R 6x300 1.3 22.05 +/- 0.25
GCN Circular 10794
Subject
GRB 100418A: Subaru late-time optical imaging and spectroscopy
Date
2010-05-24T05:38:17Z (16 years ago)
From
Nobuyuki Kawai at Tokyo Tech <nkawai@hp.phys.titech.ac.jp>
T. Hattori and K. Aoki (Subaru Telescope)
report on behalf of the Subaru GRB team:
We observed the field of GRB 100418A (Marshall et al. GCN 10612) with FOCAS
on Subaru Telescope under an excellent condition (seeing 0.3"-0.4"),
starting at 12:13 UT on May 14 2010, 25.63 days after the trigger.
Single exposure of 120 seconds in each V, Rc, and Ic bands was acquired.
We detected and resolved the host galaxy (Malesani GCN 10621), but could not
find any point source in the galaxy. The host galaxy magnitudes (Vega
system) are V=22.62 +-0.06, Rc=21.90 +-0.03 and Ic=21.34 +-0.05.
Rc-band magnitude is consistent with the values reported in GCN 10727
(R=21.85 +-0.05 at 17.7 days after) and GCN 10783 (R=21.86 +-0.06 at 26.0
days after).
No time variation of R-band magnitude was thus detected during 17.7 days and
26.0 days.
We also performed optical spectroscopy for the host galaxy starting
12:35 UT May 14.
We used two settings of the spectrograph with 0.8" width slit.
One was covering the wavelengths between 3900 A and 8300 A, and the other
between 5800 A and 1 micron.
The integration time of the each setting was 1 hour (1200 seconds x 3).
We found strong emission-lines such as [O II], Hgamma, Hbeta, [O III]
at z=0.624 which are same as reported in GCN 10620 and GCN 10624.
The continuum of the galaxy is very similar to that of the nearby blue
compact dwarf galaxy NGC 1140.
We could not identify any supernova feature like broad emission-lines
and bumps.
GCN Circular 10783
Subject
GRB 100418A: CrAO optical observations
Date
2010-05-19T19:25:13Z (16 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB
follow-up collaboration:
We observed the field of the Swift GRB 100418A (Marshall et al. GCN 10612)
with Shajn telescope of CrAO between (UT) May, 14 21:07 -- 22:48 under
photometric weather conditions and mean seeing of about 2 arcsec.
The preliminary photometry of the afterglow+host in a stacked image based on
USNO-B1.0 star 1014-0271368 (RA(J2000) = 17:05:26.42 Dec(J2000)=
+11:27:32.9) assuming R=17.32 is following:
T0+ Filter, Exposure, mag.
(mid, d) (s)
26.0332 R 90x60 21.86 +/-0.06
The photometry is compatible with R-magnitude reported by Perley et al, GCN
10727 (R=21.85+/-0.05 at 17.739 days) and still brighter than assumed
R-magnitude of the normal type of host galaxy (SDSS based ugriz-> R
conversion) which cannot be explained solely by afterglow contribution
fading steeper than power law with decay index of .~0.8.
GCN Circular 10727
Subject
GRB 100418A: Keck imaging
Date
2010-05-07T23:19:17Z (16 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, S. B. Cenko, A. A. Miller, D. Poznanski, A. V. Filippenko,
J. S. Bloom (UC Berkeley), and P. Nugent (LBNL) report:
We imaged the field of GRB 100418A (Marshall et al., GCN 10612) with the
Low Resolution Imaging Spectrometer on the Keck I 10-m telescope during
morning twilight on 2010-05-06 UT. Two exposures of 380 seconds each
were acquired in the g and R bands simultaneously. The midpoint of the
observation was 14:54 UT, 17.739 days after the GRB.
At the position of the afterglow and calibrating to 9 nearby unsaturated
SDSS stars, we measure magnitudes of:
g = 22.67 � 0.07
R = 21.85 � 0.05
The g-band magnitude is marginally consistent with the SDSS magnitude
(Malesani et al., GCN 10621) of g = 22.89 � 0.17, and suggests that the
UVOT flattening (Marshall et al., GCN 10720) is primarily due to the
host galaxy, not an associated supernova. Our reported R-band magnitude
is significantly brighter than the host, but this excess is consistent
with an afterglow origin (Bikmaev et al., GCN 10726). Additional
follow-up observations will be necessary to comment on the presence (or
absence) of a supernova counterpart.
GCN Circular 10726
Subject
GRB 100418A: RTT150 optical observations
Date
2010-05-07T03:44:59Z (16 years ago)
From
Irek Khamitov at TUG <irekk@tug.tug.tubitak.gov.tr>
I. Bikmaev (KSU/AST), I. Khamitov (TUG), N. Sakhibullin (KSU/AST),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
report:
The optical afterglow of GRB 100418A (Marshall et al., GCN 10612, Filgas
et al., GCN 10617) was observed with Russian-Turkish 1.5-m telescope
(RTT150,Bakirlitepe, TUBITAK National Observatory, Turkey) every night
during May 1/2 - 6/7, 2010.
We obtained 4 - 12 exposures by 900 sec each in Rc filter.
Estimates of Rc magnitudes were made relative to the nearby
USNO-B1.0 star 1014-0271368 (R2Mag=17.32).
Additionally we made 4 x 900 sec exposures in g',r',i' SDSS filters
in May 5/6, 2010. OT is still existed in all filters as compared with
SDSS host images.
We found that OT brightness has decreased from Rc = 21.25 in April 28
(Bikmaev et al., GCN 10700, T+0.792 Ms) to Rc = 21.60 +/- 0.05 in May 5,
2010 (T+1.48 Ms) following a power-law decay with an index of -0.8 +/- 0.1,
without plateau reported by Marshall et al. (GCN10720).
In May 7, UT(mean) = 0h50m, we estimated Rc = 21.7+/-0.07 mag.
It means that OT is began to fade faster after T+1.48 Ms.
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GCN Circular 10720
Subject
GRB 100418A: Flattening of the Swift/UVOT Optical Light Curve
Date
2010-05-05T20:10:36Z (16 years ago)
From
Frank Marshall at GSFC <marshall@milkyway.gsfc.nasa.gov>
F.E. Marshall (NASA/GSFC) and S.T. Holland (CRESST/USRA/GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT has monitored the optical flux from GRB 100418A
since shortly after the BAT trigger (Marshall et al., GCN Circ. 10612).
The highest flux was seen at about T+50 ks, followed by a power-law
decay with an index of -1.0 +/- 0.1 in the UVOT white filter
(Siegel et al., GCN Circ. 10645). The power-law decay continued
until about T+700 ks, after which time the flux has remained
approximately constant at about 22.3 mag in the white filter
through the latest observation at about T+1.2 Ms.
This late plateau may be due to flux from the host galaxy
(Malesani, GCN Circ. 10621). We note that the white magnitude is 0.6 mag
brighter than the SDSS g magnitude, but this may be due to
the very different filter responses. Other possibilities for the plateau
include a very bright SN (Malesani, GCN Circ. 10621; Filgas et al.,
GCN Circ. 10644) or optical flaring, which was seen earlier
in the light curve (Bikmaev, GCN Circ. 10635; Covino et al.,
GCN Circ. 10646).
Swift continues to monitor GRB 100418A and observations with other
telescopes are encouraged.
The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0.07 (Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric
system described in Poole et al. (2008, MNRAS, 383, 627).
GCN Circular 10700
Subject
GRB 100418A: RTT150 optical observations
Date
2010-04-28T21:04:18Z (16 years ago)
From
Irek Khamitov at TUG <irekk@tug.tug.tubitak.gov.tr>
I. Bikmaev (KSU/AST), I. Khamitov (TUG),
S. Melnikov, N. Sakhibullin (KSU/AST),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
report:
The optical afterglow of GRB 100418A (Marshall et al., GCN 10612, Filgas
et al., GCN 10617) was observed with Russian-Turkish 1.5-m telescope
(RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey) in April
23/24 and April 27/28, 2010, in partially cloudy conditions. We obtained
one useful 900 sec image in Rc-band in April 24 and nine 900 sec images
in April 28. In spite of bright Moon in April 27/28 observations OT is
clearly detected in combined image.
In the Table below we give our Rc estimates of the OT brightness
relative to the nearby USNO-B1.0 star 1014-0271368 (R2Mag=17.32).
Date UT (T-T0),h Rc err
Apr.24 00:20 123.1 20.6 +/-0.10
Apr.28 00:50 220.0 21.25 +/-0.05
Preliminary Rc-light curve can be found at:
http://hea.iki.rssi.ru/grb/100418a/indexeng.html
OT is still brighter compared with its host galaxy (Malesani, GCN10621)
and further spectroscopic and photometric observations of this event are
very important to check possible SN contribution in the OT flux.
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GCN Circular 10694
Subject
GRB 100418A: Terskol optical observations
Date
2010-04-27T09:50:55Z (16 years ago)
From
Alina Volnova at SAI MSU <alinusss@gmail.com>
M. Andreev, �A. Sergeev (Terskol Branch of �Institute of Astronomy),
A. Volnova (SAI MSU), A. Pozanenko (IKI) report on behalf of larger
GRB follow-up collaboration:
We observed the field of the Swift GRB 100418A (Marshall et al. GCN
10612) with the Z-600 telescope of Mt.Terskol observatory in R-filter
between (UT) Apr. 20 19:47 - 23:00 under good weather conditions with
mean seeing of about 1.6 arcsec. The optical afterglow (Marshall et al. GCN
10612, Filgas et al. GCN 10617) is clearly detected in enhanced XRT
error circle (Osborne et al. GCN 10614). The photometry of the
afterglow in a stacked image based on USNO-B1.0 star 1014-0271368
(RA(J2000) = 17:05:26.42 Dec(J2000)= +11:27:32.9) assuming R=17.32 is
following:
T0+ � � � Filter, � Exposure, � �mag. � � � � � � � UL
(mid, d) � � � � � �(s)
2.0175 � R � � � � 50x180 � � � 19.85 +/- 0.18 � 20.8
GCN Circular 10665
Subject
GRB 100418A: ROVOR optical measurements at 35 hours
Date
2010-04-23T23:41:42Z (16 years ago)
From
J. Ward Moody at BYU <rovor.byu@gmail.com>
J. W. Moody, D. Laney, R. Pearson, and C. Pace report for the BYU ROVOR team:
Beginning approximately 35 hours after the initial detection of GRB 100418A we
obtained BVR optical data using the BYU WMO 0.9m telescope.
Preliminary magnitudes were found by referencing against USNO-B1.0
star 1014-0271368 (RA(J2000) = 17:05:26.42, Dec(J2000) = +11:27:32.9).
Assuming its values are B=18.66, R=17.32 (from catalog) and V=18.0
(our estimate) we obtain the following values:
post burst
t_mid(hr) exp.(min) filter mag. error
37.18 25 B 19.9 0.15
35.91 25 V 19.3 0.1
35.25 20 R 18.5 0.1
Poor weather has prevented subsequent observations.
GCN Circular 10661
Subject
GRB 100418A: Possible Evidence for a Supernova
Date
2010-04-23T19:18:34Z (16 years ago)
From
Stephen Holland at USRA/NASA/GSFC/SSC <Stephen.T.Holland@nasa.gov>
S. T. Holland (CRESST/USRA/GSFC), F. E. Marshall (NASA/GSFC),
M. Page (MSSL-UCL), M. de Pasquale (MSSL-UCL), and
M. H. Siegel (PSU) report on behalf of the Swift/UVOT team:
Swift/UVOT white photometry of GRB 100418A reveals a light curve
with a rise and decay that are broadly similar to the white light
curve of GRB 060218/SN2006aj. The UVOT spectral energy distribution
at 6400 s is consistent with a power law with a spectral index of beta
= 0.2 (f = nu^-beta), which is similar to the UVOT spectral energy
distribution for GRB 060218/SN2006aj at 9300 s. In addition, the
X-ray light curve of GRB 100418A is broadly similar to the X-ray light
curves of GRB 100316D and GRB 060218, both of which had supernova
components. Therefore, we suggest that the brightening of the
afterglow of GRB 100418A seen at approximately 10,000 s (Bikamev et
al. 2010, GCNC 10635; Siegel et al. 2010, GCNC 10645) may be the shock
breakout from a supernova associated with this burst. If this is the
case, and the supernova is similar to SN1998bw, then the supernova has
not yet reached maximum light. Ground based observations to determine
if a supernova is present are encouraged.
GCN Circular 10650
Subject
Radio afterglow detection of GRB 100418A with the EVLA
Date
2010-04-22T17:47:34Z (16 years ago)
From
Poonam Chandra at Royal Mil. College Canada <Poonam.Chandra@rmc.ca>
Poonam Chandra (RMC) and Dale A. Frail (NRAO)
report on behalf of a larger collaboration:
We used the Expanded Very Large Array (EVLA) to observe the Swift GRB
100418A (Marshall et al., GCN 10612) on 2010 Apr 21 UT.
We detect the GRB afterglow with a flux density of 458 +/- 20 uJy
at the GROND optical afterglow position (Filgas et al, GCN 10617).
The EVLA is undergoing active commissioning and as such these results
should be considered preliminary. Further observations are planned.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities Inc.
GCN Circular 10648
Subject
GRB 100418A: Continued PAIRITEL NIR Observations
Date
2010-04-22T12:36:14Z (16 years ago)
From
Adam Morgan at U.C. Berkeley <qmorgan@gmail.com>
A. N. Morgan, D. A. Perley, C. R. Klein, and J. S. Bloom (UC Berkeley) report:
We continued to observe the location of the optical afterglow of GRB
100418A (Marshall et al., GCN 10612) with the 1.3m PAIRITEL located at
Mt. Hopkins, Arizona for a second epoch beginning at 2010-04-20 07:59
UT, ~34.8 hours after the Swift trigger. In mosaics (effective
exposure time of 1.27 hours) taken simultaneously in the J, H, and Ks
filters, we observe that the afterglow has faded approximately 1
magnitude since our first epoch (Klein et al., GCN 10627).
Unfortunately, poor weather conditions prevented further observations
on 2010-04-21 and 2010-04-22.
The preliminary photometry yields:
post burst
t_mid (hr) exp.(hr) filt mag m_err
35.81 1.27 J 18.0 0.1
35.81 1.27 H 17.2 0.1
35.81 1.27 Ks 16.3 0.1
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 10647
Subject
GRB 100418A: WSRT Radio Detection
Date
2010-04-21T23:39:12Z (16 years ago)
From
Alexander van der Horst at NASA/MSFC <Alexander.J.VanDerHorst@nasa.gov>
A.J. van der Horst (NASA/MSFC/ORAU), A.P. Kamble, R.A.M.J. Wijers,
E. Rol (U of Amsterdam), C. Kouveliotou (NASA/MSFC) and K. Wiersema
(U of Leicester) report on behalf of a large collaboration:
"We observed the position of the GRB 100418A afterglow with the
Westerbork Synthesis Radio Telescope at 4.8 GHz at April 20 20.74 UT
to April 21 8.71 UT, i.e. 1.98 - 2.48 days after the burst (GCN 10612).
We detect a radio source with a flux density of 369 +/- 29 microJy
at the position of the optical counterpart (GCN 10616).
We would like to thank the WSRT staff for rapidly scheduling
and obtaining these observations."
GCN Circular 10646
Subject
GRB100418A: REM possible afterglow detection
Date
2010-04-21T19:36:39Z (16 years ago)
From
Stefano Covino at Brera Astronomical Observatory <stefano.covino@gmail.com>
S. Covino (INAF/Brera), D. Fugazza (INAF/Brera), L.A. Antonelli (INAF/Roma), D. Malesani (DARK/NBI), on behalf of the REM team report:
The robotic 60-cm REM telescope located at La Silla (Chile) observed automatically the field of GRB 100418A (GCN 10612, Marshall et al.) from April 19 3:25 UT to 4:34 UT (about 6.2 to 7.4 hr from the burst) in the optical and in the near-infrared.
Nothing is visible at the position of the optical counterpart reported by GROND (GCN 10617, Filgas et al.) except for a single H-band frame with mean time 4:14 UT (about 6.9 hr after the burst) and 5 min exposure. During this observation the afterglow is clearly detected at H=14.3 +- 0.2. The 3sigma upper limits in other H-band frames obtained always with 5 min exposure is H>15.2.
This rapid variability resembles the one observed by Bikmaev et al. (GCN 10635) with the RTT150 which, however, observed the field several hours before. Given this very unusual behavior, we encourage inspection of other datasets taken at comparable epochs.
GCN Circular 10645
Subject
GRB 100418A: Continuing Swift/UVOT Observations
Date
2010-04-21T19:26:57Z (16 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@astro.psu.edu>
M. H. Siegel (PSU), F. E. Marshall (NASA/GSFC), S. T. Holland
(NASA/GSFC), M. M. Chester (PSU), M. de Pasquale (MSS-UCL) and
S. R. Oates (MSSL-UCL) report on behalf of the Swift/UVOT team.
Ongoing Swift/UVOT observations of the field of GRB 100418A
(Marshall et al., GCN Circ. 10612) have continued to monitor the
behavior of the optical transient. UVOT photometry taken about
50 ks after the burst shows an increase in brightness of about a
magnitude compared to the initial detection, confirming the late
increase in brightness reported by Bikamev et al. (GCN Circ. 10635).
The OT has since decayed from this peak with a decay rate of -1.0+-0.1
in the UVOT white filter. This decay is slightly shallower than the
decay observed by Malesani et al. (GCN Circ. 10631, 10643), Updike et
al. (GCN Circ. 10637) and Filgas et al. (GCN Circ 10644). Such a late
peak in brightness is very unusual and Swift will continue to monitor
the GRB.
Photometry from the summed exposures is reported below:
FILTER T_start(s) T_stop Exposure Mag
=========================================================
white fc 88 237 147 20.62+-0.29
white 88 1548 390 20.58+-0.20
white 6143 6343 196 20.32+-0.20
white 50996 52990 1959 19.38+-0.03
white 86204 92193 2308 19.77+-0.04
white 149282 156466 3812 20.54+-0.06
=========================================================
The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0.07 (Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric
system described in Poole et al. (2008, MNRAS, 383, 627).
GCN Circular 10644
Subject
GRB 100418A: further GROND observations and light curve fit
Date
2010-04-21T19:20:41Z (16 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
R. Filgas (MPE Garching), D. A. Kann, S. Klose (all Tautenburg),
M. Nardini, and J. Greiner (all MPE Garching), report on behalf of the GROND
team:
GROND on La Silla (Greiner et al. 2008, PASP 120, 405) continues
observing the afterglow of GRB 100418A. GROND data, with the first epoch
at 28 ks after the burst and the last data point at 133 ks after the
burst, in combination with data from Updike et al. (GCN 10619), Antonelli
et al. (GCN 10620), Malesani (GCN 10621), Pearson et al. (GCN 10626),
Malesani et al. (GCN 10631), Rumyantsev et al. (GCN 10634), Bikmaev et al.
(GCN 10635), Updike et al. (GCN 10637), and Bikmaev et al. (GCN 10643),
show that the R-band afterglow light curve had a break at t = 1.11 +/-
0.01 days and is now decaying with a slope of 2.41 +/- 0.08.
While the steep decay of the afterglow is in favor of a SN search, the
bright host (Malesani, GCN 10621) might make a detection difficult.
Assuming a SN 1998bw template, a Galactic visual extinction along the line
of sight of 0.2 mag, no GRB host extinction but 0.2 mag host extinction
for SN 1998bw, we predict the following SN peak times and magnitudes:
band dt/days mag
V 21.5 24.5
R 22.5 23.7
I 24.0 22.9
J 29.5 22.8
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GCN Circular 10643
Subject
GRB 100418A: RTT150 optical observations
Date
2010-04-21T15:06:43Z (16 years ago)
From
Irek Khamitov at TUG <irekk@tug.tug.tubitak.gov.tr>
I. Bikmaev (KSU/AST), I. Khamitov (TUG),
S. Melnikov, N. Sakhibullin (KSU/AST),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
report:
The optical afterglow of GRB 100418A (Marshall et al., GCN 10612, Filgas
et al., GCN 10617) was observed with Russian-Turkish 1.5-m telescope
(RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey) in April 20/21, 2010,
at moderate seeing conditions.
We obtained a serie of 600 sec and 300 sec images in Rc-band.
The Table gives our Rc value estimation relative nearby USNO-B1.0
star 1014-0271368 (R2Mag=17.32).
April 21, 2010
UT (T-T0), h Rc err
=================================
00:48 51.6 20.05 +/-0.03
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GCN Circular 10637
Subject
GRB 100418A: SARA second epoch
Date
2010-04-20T21:07:59Z (16 years ago)
From
Adria C. Updike at Clemson U <aupdike@clemson.edu>
Adria C. Updike, Dieter H. Hartmann (Clemson University), and Chris De
Pree (Agnes Scott College) report:
We re-observed the field of GRB 100418A (Marshall et al., GCN 10612) using
the 0.9m SARA telescope located at KPNO beginning 1.44 days after the
trigger. Observations consisted of 40 minutes in the R band. We detect
the afterglow (Filgas et al., GCN 10617) at R = 19.3 +/- 0.1, fading 1.0
mag from our previous detection (upon comparison to USNO B1.0 catalog
field stars). Further observations are planned.
GCN Circular 10635
Subject
GRB 100418A: RTT150 observations during the optical afterglow maximum
Date
2010-04-20T18:39:42Z (16 years ago)
From
Irek Khamitov at TUG <irekk@tug.tug.tubitak.gov.tr>
I. Bikmaev (KSU/AST), I. Khamitov (TUG),
S. Melnikov, N. Sakhibullin (KSU/AST),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
report:
The optical afterglow of GRB 100418A (Marshall et al., GCN 10612, Filgas
et al., GCN 10617) was observed with Russian-Turkish 1.5-m telescope
(RTT150,Bakirlitepe, TUBITAK National Observatory, Turkey) in April 18/19
and April 19/20, 2010, in partially cloudy conditions. We obtained a serie
of 300 sec images in Rc-band in April 18/19, and serie of 600 sec images
in April 19/20.
We found that during April 18 set OT shows strong brightness variations of
Rc ~ 18-20 mag within hour time scale. In the Table below we give our Rc
estimates relative to the nearby USNO-B1.0 star 1014-0271368 (R2Mag=17.32).
April 18
UT (T-T0),h Rc err
=================================
21:43 0.5 20.29 +/-0.10
22:38 1.5 >20.50 3-sigma image limit
23:25 2.25 18.64 +/-0.04
23:51 2.6 18.30 +/-0.04
23:58 2.9 18.33 +/-0.02
=================================
April 20
UT (T-T0),h Rc err
=================================
00:40 27.5 18.88 +/-0.03
RTT-150 data shows that brightness of OT sharply increased
from 20 to 18 mag at (T-T0) ~ 2 hours. The OT was observed at maximum
brigtness atapproximately 2.6 hours after the burst and then its flux
started to decline, which is consistent with other measurements
made later on (Rumyantsev et al., GCN 10634, Filgas et al GCN 10617).
The brightening of the OT is shown in the following RTT150 images:
http://hea.iki.rssi.ru/grb/100418a/indexeng.html
--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
GCN Circular 10634
Subject
GRB 100418A: optical observations
Date
2010-04-20T15:55:58Z (16 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev, D. Shakhovkoy (CrAO), A. Pozanenko (IKI) report on behalf of
larger GRB follow-up collaboration:
We observed the field of the Swift GRB 100418A (Marshall et al. GCN 10612)
with AZT-11 telescope of CrAO between (UT) Apr. 19 01:26 -- 01:54 under
poor seeing of about 4 arcsec. The optical afterglow (Marshall et al. GCN
10612, Filgas et al. GCN 10617) is clearly detected in enhanced XRT error
circle (Osborne et al. GCN 10614). The coordinates of the afterglow are
(J2000) RA= 17:05:27.08 Dec= +11:27:42.3
The photometry of the afterglow in a stacked image based on USNO-B1.0 star
1014-0271368 (RA(J2000) = 17:05:26.42 Dec(J2000)= +11:27:32.9) assuming
R=17.32 is following:
T0+ Filter, Exposure, mag.
(mid, d) (s)
0.1883 R 9x180 18.54 +/-0.03
A finding char can be found at
http://grb.rssi.ru/GRB100418A/GRB100418a_100418_R_azt11.gif
GCN Circular 10633
Subject
GRB 100418A: MASTER-Net optical observations
Date
2010-04-20T10:45:29Z (16 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <gcncirc@observ.inetcomm.ru>
K.Ivanov, S.Yazev, N.M.Budnev, E.Konstantinov, V.Lenok, O.Gres, O.
Irkutsk State University
V.Yurkov, Yu.Sergienko, D.Varda, A.Garusina Blagoveschensk Educational State
University, Blagoveschensk
E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina,
D.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov,
D.Zimnukhov, M. Kornilov
Sternberg Astronomical Institute, Moscow State University
A. Tlatov, A.V. Parkhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory
V.Krushinski, I.Zalozhnih, T.Kopytova, A.Popov
Ural State University, Kourovka
MASTER robotic telescope (MASTER-Net: http://observ.pereplet.ru,
testing telescope) located at Tunka Valley (Baykal, Siberia) was
responted to the GRB 100418A (Swift Bat alert, Marshall et al, GCN CIRC
10612) 21 sec after Notice time (~ 8 sec delay in internet socket) and
31 s after the GRB time ( Sun Alt -8 degrees) .
There is now OT on the first 10-s exposition time unfiltered images
inside Swift XRT error box (Pagani et al., GCN CIRC 10622)
brighter 14.5.
The message may be cited.
mailto: lipunov@sai.msu.ru
GCN Circular 10631
Subject
GRB 100418A: VLT optical observations
Date
2010-04-20T09:21:50Z (16 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
Daniele Malesani, Eliana Palazzi, and Simone Scaringi report:
We obtained an R-band image of the afterglow of GRB 100418A (Marshall et
al., GCN 10612; Filgas et al., GCN 10617) with the X-shooter acquisition
camera 34.63 hr after the GRB. The afterglow has decayed by 1.11+-0.03
mag since our previous observation taken 8.37 hr after the GRB
(Antonelli et al., GCN 10620).
We encourage further observations at all wavelengths of this interesting
event. We acknowledge support from the ESO staff at Paranal, in
particular Alvaro Alvarez, Claudia Cid, and Fernando Selman.
[GCN OPS NOTE(20apr10): Per author's request, Scaringi was added
to the author list.]
GCN Circular 10630
Subject
GRB 100418A: SMA submm detection
Date
2010-04-20T06:40:43Z (16 years ago)
From
Antonio Deugarte at IAA-CSIC <deugarte@iaa.es>
S. Martin (ESO), G. Petitpas (SMA), A. de Ugarte Postigo (INAF-OAB),
M. Gurwell (SMA), A.J. Castro-Tirado, J. Gorosabel (IAA-CSIC),
D. Garcia-Apaadoo, C. de Breuck, A. Lundgren (ESO) report:
"We have observed the field of GRB 100418A (Marshall et al., GCNC
10612) from SMA in the 345 GHz band starting on April 19th 13:00 UT.
In a preliminary analysis of the data we detect a single source coincident
with the position of the afterglow with a flux density of 20+/-2.4 mJy.
Further observations of this very peculiar source are encouraged."
GCN Circular 10627
Subject
GRB 100418A PAIRITEL NIR Observations
Date
2010-04-20T02:47:30Z (16 years ago)
From
Adam Morgan at U.C. Berkeley <qmorgan@gmail.com>
C. R. Klein, A. N. Morgan, D. A. Perley, and J. S. Bloom (UC Berkeley) report:
We observed the location of the optical afterglow of GRB 100418A
(Marshall et al., GCN 10612) with the 1.3m PAIRITEL located at Mt.
Hopkins, Arizona. Observations began at 2010-04-19 07:51:27 UT, ~10.69
hours after the Swift Trigger, under non-ideal sky conditions, and
continued until clouds obscured the sky. In mosaics (effective
exposure time of 0.92 hours) taken simultaneously in the J, H, and Ks
filters, we detect the afterglow (Filgas et al., GCN 10617; Updike et
al., GCN 10619; Antonelli et al., GCN 10620; Pearson et al., GCN
10626).
The preliminary photometry yields:
post burst
t_mid (hr) exp.(hr) filt mag m_err
11.13 0.92 J 16.8 0.1
11.13 0.92 H 15.9 0.1
11.13 0.92 Ks 15.3 0.1
We note that our J band point is consistent with little to no fading
since the GROND detection ~3.6 hours prior (using J_AB = J_2mass +
0.90). This is consistent with the shallow decay implied by the R
band magnitudes in this time period reported thus far (Filgas et al.,
GCN 10617; Updike et al., GCN 10619; Antonelli et al., GCN 10620;
Pearson et al., GCN 10626), and with the the non-fading behavior seen
in the UVOT data (Siegel et al., GCN 10625). Further, the XRT light
curve is roughly flat between ~1000s and ~1 day (see
http://astro.berkeley.edu/~nat/Swift/00419797/xrt/swx00419797.html),
indicating a long optical/X-ray plateau phase. Continued observations
are encouraged.
Intermittent clouds led to highly variable transmission and sky
brightnesses during the PAIRITEL observations. 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 10626
Subject
GRB 100418A: ROVOR optical afterglow detection
Date
2010-04-19T22:12:24Z (16 years ago)
From
J. Ward Moody at BYU <rovor.byu@gmail.com>
R. Pearson, J. Ward Moody, and C. Pace report for Brigham Young
University's (BYUs) ROVOR team:
Beginning 9.12 hours after the initial Swift detection of GRB 100418A
(GCN 10612), the 16-inch ROVOR telescope observed its optical
afterglow. Twenty-eight 2 minute R band exposures were recorded at
high airmass (2.48) and subsequently averaged together; a combined
frame of 56 minutes was produced. An optical afterglow was located at
the position specified by Filgas, Klose, and Greiner (GCN 10617).
We report a middle observing time of 06:55:21.474 (9.75 hrs
post-burst) and a R band magnitude of 18.2+/-0.2mag. It was calibrated
using GSC 00984-01465 located at 17:05:55.02+11:27:55.46 (J2000).
Additional follow-up observations are scheduled with ROVOR as well as
BYU's 36-inch telescope on West Mountain Observatory, supported by the
NSF grant AST-0618209.
GCN Circular 10625
Subject
GRB 100418A: Swift/UVOT Observations
Date
2010-04-19T21:54:40Z (16 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@astro.psu.edu>
M. H. Siegel (PSU) and F. Marshall (NASA/GSFC) report on behalf
of the Swift/UVOT team.
The Swift/UVOT began settled observations of the field of GRB
100418A 87s after the BAT trigger (Marshall et al., GCN Circ. 10612).
Data summed from the first and second orbits reveals the source
reported by Marshall et al. The source shows no fading between
the first and second orbits within the photometric uncertainties.
The photometry is consistent with a constant source with a white
magnitude of 20.48+-0.13. This likely represents the GRB host
galaxy reported by Malesani (GCN Circ. 10621) and not the
afterglow reported by Filgas et al. (GCN Circ. 10617), Updike
et al. (GCN Circ. 10619) and Antonelli et al. (GCN Circ. 10620).
The UVOT position of the source is:
RA(J2000.0) = 17:05:26.96 = 256.36278 (deg)
Dec(J2000.0) = +11:27:41.9 = +11.46167 (deg)
with a 90% confidence interval of 0."67.
The 3-sigma upper limits for the finding chart (fc) and
summed exposures from the first and second orbits are reported
below:
FILTER T_start(s) T_stop Exposure Mag/3UL
========================================================
white fc 87 237 147 20.62+-0.29
white 89 1548 390 20.58+-0.20
white 6143 6343 196 20.32+-0.20
v 628 6754 491 >19.90
b 554 6138 294 20.61+-.44
u 299 7348 697 20.47+-0.41
uvw1 678 7164 491 20.47+-0.42
uvm2 653 6959 491 20.09+-0.32
uvw2 604 6548 308 20.73+-0.54
=======================================================
The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0.07 (Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric
system described in Poole et al. (2008, MNRAS, 383, 627).
GCN Circular 10624
Subject
GRB 100418A: Gemini-N redshift confirmation
Date
2010-04-19T14:51:54Z (16 years ago)
From
Antonino Cucchiara at PSU <cucchiara@astro.psu.edu>
A. Cucchiara and D. B. Fox (PSU) report on behalf of a
larger collaboration:
"Starting on 2010 April 19.41 UT we used the GMOS spectrograph
on the Gemini North 8-m telescope to observe the field of the
Swift GRB 100418A (Marshall et al. GCN 10612).
A sequence of 2x1200s spectra were obtained covering the
spectral range of 4000-8000A.
A series of metal absorption features were identified (MgII2796,
2803,FeI3720, Ca H&K, CaI4227) and H-beta in emission at the
common redshift of z= 0.624, confirming the previously reported
result of Antonelli et al. GCN 10620.
We thank the Gemini staff for performing this observation,
in particular A. Fritz."
GCN Circular 10622
Subject
GRB 100418A: Swift-XRT Refined Analysis
Date
2010-04-19T12:05:00Z (16 years ago)
From
Claudio Pagani at U of Leicester <cp232@star.le.ac.uk>
C. Pagani (U. Leicester), A. P. Beardmore (U. Leicester)�� and F. E.
Marshall (NASA/GSFC) report on behalf of the Swift-XRT team:
We have analysed 3.7 ks of XRT data for GRB 100418A (Marshall et al. GCN
Circ. 10612), from 70 s to 7.3 ks after the BAT trigger. The data
comprise 97 s in Windowed Timing (WT) mode (the first 7 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 Osborne et
al. (GCN. Circ 10614).
The light curve can be modelled with an initial power-law decay with an
index of alpha=4.23 (+0.17, -0.16), followed by a break at T+474 s to an
alpha of 0.21 (+0.22, -0.24).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 4.29 (+0.33, -0.30). The
best-fitting absorption column is 2.1 (+/-0.4) x 10^21 cm^-2, in excess
of the Galactic value of 4.8 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 2.0 x 10^-11 (1.3 x 10^-10) erg cm^-2
count^-1.
If the light curve continues to decay with a power-law decay index of
0.21, the count rate at T+24 hours will be 0.012 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.5 x
10^-13 (1.6 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00419797.
This circular is an official product of the Swift-XRT team.
GCN Circular 10621
Subject
GRB 100418A: host galaxy detection in the SDSS
Date
2010-04-19T10:32:36Z (16 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
Daniele Malesani (DARK/NBI) reports:
At the position of the optical afterglow of GRB 100418A (Marshall et
al., GCN 10612; Filgas et al., GCN 10617), a faint, compact object is
well visible in the SDSS frames and catalogs ( Abazajian et al. 2009,
ApJS, 182, 543), in the g, r, and i bands.
The (AB) model magnitudes as reported in the SDSS catalog are:
u: not detected
g = 22.89 +- 0.17
r = 22.41 +- 0.16
i = 21.94 +- 0.17
z: not detected
See e.g.
http://cas.sdss.org/astrodr7/en/tools/explore/obj.asp?id=758879770841908118
The host detection is consistent with the relatively low redshift and
the report of nebular emission lines superimposed on the bright
afterglow continuum (Antonelli et al., GCN 10620). A SN as bright as
SN1998bw would peak at r ~ 24 at the position of GRB 100418A.
GCN Circular 10620
Subject
GRB100418A: VLT/X-shooter redshift and photometry
Date
2010-04-19T08:56:13Z (16 years ago)
From
Stefano Covino at Brera Astronomical Observatory <stefano.covino@brera.inaf.it>
L.A. Antonelli, J.R. Maund, E. Palazzi, P. Goldoni, S.D. Vergani, H. Flores, A. de Ugarte Postigo, S. Covino, J. Fynbo, J. Hjorth, D. Malesani, J. Sollerman, C.C. Thoene, on behalf of the X-shooter GRB collaboration report:
We observed the field of GRB 100418A (Marshall et al. 2010, GCN 10612) with VLT/X-Shooter at Cerro Paranal (Chile). The observation started on Apr 19, at 5:32 UT (about 8.37 hrs after the burst) under very good observing conditions (seeing about 0.7"). The object reported by Filgas and Greiner (GCN 10617) is clearly seen in our image at flux level of R = 18.1+/- 0.1 mag calibrated against USNO B.1 catalog.
Spectra were acquired and in a preliminary analysis they show an abundance of UV absorption lines (Fe II, Mg II, Mg I, Mn II, Ca H,K) as well as [O II] emission at z = 0.6235 (wavelength calibration was obtained with archive calibration data).
We acknowledge the Paranal staff for the support.
GCN Circular 10619
Subject
GRB 100418A: SARA observations
Date
2010-04-19T08:03:11Z (16 years ago)
From
Adria C. Updike at Clemson U <aupdike@clemson.edu>
Adria C. Updike, Dieter H. Hartmann (Clemson University), and Brian Murphy
(Butler University) report:
We observed the field of GRB 100418A (Marshall et al., GCN 10612) using
the 0.9m SARA telescope located at KPNO beginning 10 hours and 18 min
after the trigger. We detect the afterglow (Filgas et al., GCN 10617) in
our first 10 min exposure at high airmass (2.1) at a magnitude of R = 18.3
upon comparison to the USNO B1.0 catalog. Observations are continuing.
GCN Circular 10617
Subject
GRB 100418A: GROND observations; missing author list added
Date
2010-04-19T06:06:19Z (16 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
R. Filgas (MPE Garching), S. Klose (TLS Tautenburg),
and J. Greiner (MPE Garching), report on behalf of the GROND team:
GROND (Greiner et al. 2008, PASP 120, 405), the 7-channel imager mounted at
the 2.2m ESO/MPI telescope at La Silla Observatory (Chile), started follow-up
observations of GRB 100418A (Marshall et al. 2010, GCN 10612) on Apr 19, at
4:50 UT (about 7.5 hrs after the burst).
Within the enhanced XRT 1.9 arcsec error circle reported by Osborne et al.
(GCN 10614) we find a fading point source at coordinates RA, DEC (J2000) =
17:05:27.09,
11:27:42.3
with an uncertainty of 0.5" in each coordinate and estimate the following
preliminary magnitudes (in the AB system):
g' = 19.2 +- 0.1
r' = 18.8 +- 0.1
i' = 18.4 +- 0.1
z' = 18.1 +- 0.1
J = 17.7 +- 0.1
Given magnitudes are calibrated against SDSS field stars and are not
corrected for the expected Galactic foreground extinction corresponding to a
reddening of E_(B-V)=0.07 mag in the direction of the burst (Schlegel et al.
1998).
GCN Circular 10616
Subject
GRB 100418A: GROND observations
Date
2010-04-19T06:01:52Z (16 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
GROND (Greiner et al. 2008, PASP 120, 405), the 7-channel imager mounted
at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile), started
follow-up observations of GRB 100418A (Marshall et al. 2010, GCN 10612) on
Apr 19, at 4:50 UT (about 7.5 hrs after the burst).
Within the enhanced XRT 1.9 arcsec error circle reported by Osborne et al.
(GCN 10614) we find a fading point source at coordinates RA, DEC (J2000) =
17:05:27.09,
11:27:42.3
with an uncertainty of 0.5" in each coordinate and estimate the following
preliminary magnitudes (in the AB system):
g' = 19.2 +- 0.1
r' = 18.8 +- 0.1
i' = 18.4 +- 0.1
z' = 18.1 +- 0.1
J = 17.7 +- 0.1
Given magnitudes are calibrated against SDSS field stars and are not
corrected for the expected Galactic foreground extinction corresponding to
a reddening of E_(B-V)=0.07 mag in the direction of the burst (Schlegel et
al. 1998).
GCN Circular 10615
Subject
GRB 100418A: Swift-BAT refined analysis
Date
2010-04-19T01:00:52Z (16 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
T. N. Ukwatta (GWU) 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/UMD), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC),
G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
(i.e. the Swift-BAT team):
Using the data set from T-61 to T+242 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 100418A (trigger #419797)
(Marshall, et al., GCN Circ. 10612). The BAT ground-calculated position is
RA, Dec = 256.358, 11.457 deg, which is
RA(J2000) = 17h 05m 25.8s
Dec(J2000) = +11d 27' 26.8"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 49%.
The mask-weighted light curve shows two overlapping peaks starting at ~T-10 sec,
peaking at ~T+2 sec, and ending at ~T+40 sec.
T90 (15-350 keV) is 7.0 +- 1.0 sec (estimated error including systematics).
The time-averaged spectrum from T-1.1 to T+7.8 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
2.16 +- 0.25. The fluence in the 15-150 keV band is 3.4 +- 0.5 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.47 sec in the 15-150 keV band
is 1.0 +- 0.2 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/419797/BA/
GCN Circular 10614
Subject
GRB 100418A: Enhanced Swift-XRT position
Date
2010-04-19T00:40:50Z (16 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1381 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 100418A, 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 = 256.36327, +11.46114 which is equivalent
to:
RA (J2000): 17h 05m 27.18s
Dec (J2000): +11d 27' 40.1"
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 10613
Subject
GRB 100418A: ROTSE-III Optical Limits
Date
2010-04-18T21:35:05Z (16 years ago)
From
Shashi Bhushan Pandey at ROTSE <shaship@umich.edu>
S. B. Pandey (U Mich), W. Zheng (U Mich), Limin Xiao (Louisiana State) and
T. Guver (U Arizona), report on behalf of the ROTSE collaboration:
ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe,
Turkey, responded to GRB 100418A (Swift trigger 419797), producing images
beginning 4.6 s after the GCN notice time. An automated response took the
first image at 21:10:30.5 UT, 16.7 s after the burst, and during the
gamma-ray emission, under fair conditions. We took 10 5-sec, 10 20-sec and
10 60-sec exposures. These unfiltered images are calibrated relative to
USNO A2.0 (R). Imaging is on going.
Comparison to the DSS (second epoch) reveals no new sources within the
3-sigma Swift/BAT error circle or the XRT error circle, for both single
images and coadding into sets of 10. Individual images have limiting
magnitudes ranging from 15.1-16.2; we set the following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
21:10:30.6 21:10:35.6 5 15.4 16.7 N
21:10:30.6 21:12:37.9 127 16.8 16.7 Y
Further observations are ongoing.
GCN Circular 10612
Subject
GRB 100418A: Swift detection of a burst with a possible optical afterglow
Date
2010-04-18T21:27:58Z (16 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
F. E. Marshall (NASA/GSFC), A. P. Beardmore (U Leicester),
J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC),
E. A. Hoversten (PSU), J. A. Kennea (PSU),
O. M. Littlejohns (U Leicester), C. B. Markwardt (CRESST/GSFC/UMD),
P. T. O'Brien (U Leicester), C. Pagani (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
A. Rowlinson (U Leicester), M. C. Stroh (PSU),
T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the
Swift Team:
At 21:10:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 100418A (trigger=419797). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 256.376, +11.464 which is
RA(J2000) = 17h 05m 30s
Dec(J2000) = +11d 27' 50"
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 4 sec. The peak count rate
was ~700 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 21:11:27.1 UT, 79.1 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
256.3635, 11.4619 which is equivalent to:
RA(J2000) = 17h 05m 27.24s
Dec(J2000) = +11d 27' 42.7"
with an uncertainty of 3.1 arcseconds (radius, 90% containment). This
location is 44 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
4.78e+20 cm^-2 (Kalberla et al. 2005).
The initial flux in the 2.5 s image was 1.27e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White
filter starting 87 seconds after the BAT trigger. A possible
afterglow candidate has been found in the initial data products at
the location of the XRT afterglow. The preliminary UVOT position is
RA(J2000.0) = 17:05:26.96 = 256.36233 (deg)
Dec(J2000.0) = +11:27:41.9 = +11.46164 (deg)
with an estimated uncertainty of 1.0 arcsec (radius, 90% confidence,
statistical + systematic). The estimated white magnitude is 20.7 +/-
0.3. No correction has been made for the expected extinction
corresponding to E(B-V) of 0.07.
Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.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.)