GRB 090417B
GCN Circular 9135
Subject
GRB 090417B: Swift detection of a burst
Date
2009-04-17T15:41:13Z (16 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
B. Sbarufatti (INAF-IASFPA), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), P.A. Curran (MSSL-UCL),
P. A. Evans (U Leicester), O. Godet (U Leicester),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
E. A. Hoversten (PSU), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (MSSL),
V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB),
R. Margutti (Univ Bicocca&OAB), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL), P. Romano (INAF-IASFPA),
B. A. Rowlinson (U Leicester), M. H. Siegel (PSU),
M. Stamatikos (NASA/ORAU) and T. N. Ukwatta (GSFC/GWU) report on
behalf of the Swift Team:
At 15:20:03 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 090417B (trigger=349450). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 209.706, +47.000 which is
RA(J2000) = 13h 58m 49s
Dec(J2000) = +47d 00' 01"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The TDRSS BAT light does not show much
for this 320-sec image trigger (as is typical for image triggers).
The XRT began observing the field at 15:26:30.4 UT, 387.0 seconds after
the BAT trigger. XRT found a bright, uncatalogued and fading X-ray source
located at RA, Dec 209.6931, +47.0170 which is equivalent to:
RA(J2000) = 13h 58m 46.34s
Dec(J2000) = +47d 01' 01.2"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 68 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 2.77e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 395 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The 3-sigma upper limit is white = 20.1 mag.
No correction has been made for the expected extinction corresponding to E(B-V)
of 0.02.
Burst Advocate for this burst is B. Sbarufatti (sbarufatti AT ifc.inaf.it).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN Circular 9139
Subject
GRB 090417B: Swift-BAT refined analysis
Date
2009-04-17T23:31:58Z (16 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), B. Sbarufatti (INAF-IASFPA),
J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 090417B (trigger #349450)
(Sbarufatti, et al., GCN Circ. 9135). The BAT ground-calculated position is
RA, Dec = 209.624, 46.954 deg, which is
RA(J2000) = 13h 58m 29.7s
Dec(J2000) = +46d 57' 14.1"
with an uncertainty of 4.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 94%.
The mask-weighted light curve shows that this burst started before T-200 sec
(where we start collecting event data on each trigger), slowly rises
to a peak around T+400 sec and slowly decreases out past T+950 sec
(where we stop processing the data). T90 (15-350 keV) is greater than 260 sec.
The time-averaged spectrum from T+278.7 to T+617.1 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.85 +- 0.14. The fluence in the 15-150 keV band is 2.3 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+434.93 sec in the 15-150 keV band
is 0.3 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/349450/BA/
GCN Circular 9140
Subject
GRB090417B: optical observations
Date
2009-04-18T00:23:39Z (16 years ago)
From
Johan U. Fynbo at U.Copenhagen <jfynbo@astro.ku.dk>
J. P. U. Fynbo, D. Malesani, Jens Hjorth (DARK/NBI), E. Leitet, Staffan
Linne (Uppsala), Thomas A. Ottosen (NOT), P. Jakobsson (Univ. Iceland),
report on behalf of a larger collaboration:
We observed the field of GRB 090417B (Sbarufatti et al., GCN 9135) with
the NOT equipped with ALFOSC. Observations were carried out in the B, R
and i bands.
Inside the revised XRT error circle, we find a single source detected in
all three bands, with approximate magnitude R=21.3 (at mean time Apr
17.966, 7.84 hr after the GRB).
The source is also visible in the SDSS and classified as a galaxy.
Photometry reveals that the object has approximately the same brightness
as in the SDSS (in the R band). In the NOT images the object also appears
extended. The source is thus unlikely to be the afterglow of GRB 090417B,
although it may be its host galaxy.
We acknowledge excellent support from the NOT staff and observer.
GCN Circular 9141
Subject
GRB 090417B: optical observations
Date
2009-04-18T01:25:33Z (16 years ago)
From
Igor Volkov at Asro.Inst.Slovak Acad.Sciences <volkov@ta3.sk>
On 2009 April 17 I observed the field of GRB 090417B (Sbarufatti et al.
GCN Circ. 9135) with the 0.5m reflector and ST-10XME CCD camera of Stara
Lesna (Slovak Republic) observatory. I have got 11 frames in standard Rc
system, starting at 22:10:05 UT, 23332s after the alert. In my coadded
frame (total exposition 930s)it was not possible to detect a single source
inside the refined XRT error box (Sbarufatti et al. GCN Circ. 9135) with
S/N rate more than 5, which corresponds to limiting magnitude Rc >19.9.
The time of the middle of the sequence was 22:18:00 UT. GSC2.3 catalog was
used for flux calibration.
Igor Volkov, visiting astronomer of Astronomical Institute of the Slovak
Academy of Sciences, 059 60 Tatranska Lomnica, Slovak Republic; Sternberg
Astronomical Institute, 119992 Moscow, Universitetskij pr.13;
e-mail: volkov@ta3.sk, imv@sai.msu.ru
GCN Circular 9142
Subject
GRB090417B: Xinglong TNT optical upper limit
Date
2009-04-18T05:03:56Z (16 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
L. P. Xin, X. F. Wang, W. K. Zheng, Y. L. Qiu, J. Y. Wei,
J. Wang, J. S. Deng, Y. Urata and J. Y. Hu
on behalf of EAFON report:
We have observed GRB 090417B (Sbarufatti et al., GCN 9135)
with Xinglong TNT telescope from Apr.17,15:34:38(UT),
14.5 min after the burst. The weather was cloudy.
After combined white and R band images,
no new source was found in our combined images.
The 3 sigma upper limits derived from USNO-B1.0 R2
magnitudes were shown as following:
--------------------------------------------------------
MeanTime exposure Band Mag UpperLimit? coadded?
--------------------------------------------------------
16.5min 8*40s white 20.1 yes yes
1.63hr 29*300s R 21.6 yes yes
-------------------------------------------------------
We also notice that in the location of XRT error circle,
a extended object was likely to be present,
as found by Fynbo et al (GCN 9140).
However, the S/N is very low that we could not make sure.
This message may be cited.
For more information about Xinglong GRBs Follow-up
observations, please visit the website:
http://www.xinglong-naoc.org/grb/
GCN Circular 9143
Subject
GRB 090417B: MITSuME Okayama optical upper limits
Date
2009-04-18T06:21:01Z (16 years ago)
From
Michitoshi Yoshida at Okayama Astrophysical Obs <yoshida@oao.nao.ac.jp>
D. Kuroda, M. Yoshida, K. Yanagisawa, Y. Shimizu, S. Nagayama,
H. Toda (OAO, NAOJ) and N. Kawai (Tokyo Tech) report on behalf
of the MITSuME collaboration:
We observed the field of GRB 090417B (Sbarufatti et al. GCN 9135)
with optical three color (g', Rc and Ic) CCD camera attached to
the MITSuME 50cm telescope of Okayama Astrophysical Observatory.
We started the observation at 15:29:29 UT, 566s after the burst.
There is no point source brighter than 20 mag within the XRT error
circle (Cummings et al. GCN 9139) in our 5940 sec exposure frames.
3-sigma upper limits to our observation are listed below.
We used GSC2.3 catalog for flux calibration.
Mid-UT Td EXP-T g' Rc Ic
-----------------------------------------------------------
15:34:43 880s 540s (9x60s) >19.2 >18.8 >18.4
15:44:55 1492s 1560s (24x60s) >19.9 >19.6 >19.1
15:59:37 2374s 3000s (50x60s) >20.2 >19.9 >19.4
16:29:42 4179s 5940s (99x60s) >20.3 >20.0 >19.5
-----------------------------------------------------------
GCN Circular 9144
Subject
GRB 090417B: Liverpool Telescope observations
Date
2009-04-18T09:13:41Z (16 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
C. Guidorzi (U. Ferrara), R. Smith, C.G. Mundell (Liverpool JMU),
A. Gomboc (U. Ljubljana), P. O'Brien, N. Tanvir (U. Leicester) on
behalf of a large collaboration report:
On 2009 April 18 at 03:10:50 UT we observed the Swift GRB 090417B
(Sbarufatti et al., GCN Circ. 9135) with the Liverpool Telescope
using the SDDS-R filter.
From a 6x300 s frame, inside the revised XRT error circle we clearly
detect the SDSS galaxy already mentioned by Fynbo et al. (GCN Circ. 9140).
At a mid epoch of 12.10 hrs post burst we estimate its magnitude of
r'=21.9 +/- 0.3, calibrated with respect to nearby SDSS stars.
This value is consistent with that reported in the SDSS catalogue of
21.6 mag. We therefore conclude that this source is not the afterglow of
GRB 090417B, while it could possibly be its host galaxy, as already
suggested by Fynbo et al. (GCN Circ. 9140).
GCN Circular 9145
Subject
GRB 090417B: Subaru NIR Observations
Date
2009-04-18T09:53:27Z (16 years ago)
From
Nobuyuki Kawai at Tokyo Tech <nkawai@hp.phys.titech.ac.jp>
K. Aoki, I. Tanaka, F. Nakata (Subaru Telescope), K. Ohta, S. Yuma (Kyoto U),
and N. Kawai (Tokyo Tech) report on behalf of the Subaru GRB team:
We observed the field of GRB 090417B (Sbarufatti et al. GCN 9135)
with MOIRCS on Subaru Telescope in J band Ks bands under a
cirrus condition.
The observing period is from 05:00 UT to 07:45 UT on April 18th,
about 15 hours after the burst.
In the XRT error circle, we detected the object reported
by Fynbo et al. (GCN 9140).
Roughly estimated J and Ks magnitudes of this object relative
to a nearby 2MASS star are 20.0 mag and 18.5 mag (Vega), respectively.
The object seems to be point-like under the seeing condition of
0."7, though the S/N is not so good to be definitive.
No other sources are found in the error circle.
The GRB may be a dusty GRB in the galaxy seen in the SDSS image,
or might be a high redshift GRB that appeared far behind the galaxy,
or intrinsically very faint.
GCN Circular 9153
Subject
GRB 090417B: Swift-BAT further refined analysis
Date
2009-04-18T15:31:19Z (16 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), D. M. Palmer (LANL), B. Sbarufatti (INAF-IASFPA)
(for the Swift-BAT team):
Continuing the analysis for BAT GRB 090417B (trigger #349450)
(Cummings, GCN Circ 9139) using more downlinked data, we report that
this burst is very long. The revised mask-weighted light curve
starts before T-200 sec (where we start collecting event data
on each trigger), slowly rises to a peak around T+400 sec
and slowly decreases to a minumum around T+1100 sec, then increases
to a second maximum around T+1650 sec, and then decreases again
with continuing emission past T+2100 sec (where the data stops).
The amplitudes of the two peaks are 0.09 +- 0.01 and 0.060 +- 0.006
ph/cm2/sec, resp.
GCN Circular 9155
Subject
GRB 090417B: Swift-XRT refined analysis
Date
2009-04-18T16:55:25Z (16 years ago)
From
Boris Sbarufatti at INAF-IASF-Pa <sbarufatti@ifc.inaf.it>
Sbarufatti B., Mangano V. (INAF-IASFPA) report on behalf of the
Swift Team:
We have analysed the first six orbits of Swift-XRT data obtained from
GRB 090417B (trigger 349450; Sbarufatti, et al., GCN Circ. 9135),
comprising 1456 s taken in Windowed Timing (WT) mode, from T+393 s to
T+2.0 ks, and a total exposure of 9.2 ks in Photon Counting (PC)
mode divided in 192 s from T+1.1 ks to T+1.3 ks and 9.0 ks from
T+5.4 ks to the end of the observation at T+30 ks.
Using 6972 s of XRT Photon Counting mode data and 9 UVOT images, we
find an astrometrically corrected X-ray position (using the XRT-UVOT
alignment and matching to the USNO-B1 catalogue):
RA, Dec = 209.6942, 47.0182 which is equivalent to:
RA (J2000): 13 58 46.62
Dec (J2000): +47 01 05.4
with an uncertainty of 1.4 arcsec (90% confidence). This position
lies 4.8 arcmin from the BAT refined position, outside the quoted
error circle (Cummings, et al., GCN circ. 9139).
The 0.3-10 keV X-ray light curve of the first orbit is dominated by
flaring activity, with 3 major peaks at ~T+530, ~T+1410 s and
~T+1560 s respectively. From the second orbit on the light-curve is
decaying according to a power-law with slope -1.21+/-0.05. If
decaying at this rate, the afterglow will reach a count-rate of
1.98E-2 counts/s at T+48h.
The average WT spectrum of the first orbit is best fitted by an
absorbed power-law model with a high energy cutoff. The best fit
parameters are photon index 0.40+/-0.17, cutoff energy 3.1+/-0.4 keV
and NH (9.2+/-0.6)E21 cm^-2, in large excess with respect to the
galactic value 1.6E20 cm^-2 (Kalberla et al. 2005). The average
observed(unabsorbed) flux in the 0.3-10 keV band is 1.6(2.1)E-9 ergs
cm^-2 s^-1. The average spectrum of the large double peaked flare
between T+1.3 ks and T+2.0 ks is also fitted by an absorbed power-law
model with a high energy cutoff with best fit parameters photon
index 0.46+/-0.2, cutoff energy 3.2+/-0.5 and NH (9.5+/-0.7)E21 cm^-2.
The average PC spectrum in the T+5.4 ks - T+30 ks interval is well
fitted by an absorbed power-law with photon index 2.0+/-0.1 and NH
(9.6+/-0.10E21 cm^-2. The average observed(unabsorbed) flux in the
0.3-10 keV band is 2.8(5.6)E-11 ergs cm^-2 s^-1.
The count-rate to flux conversion factor is 1.0E-10.
All quoted errors are at 90% confidence level.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00349450.
This circular is an official product of the Swift-XRT team.
GCN Circular 9156
Subject
GRB 090417B: Galaxy redshift
Date
2009-04-18T17:49:52Z (16 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
E. Berger (Harvard) and D.B. Fox (PSU) report:
"We obtained spectroscopic observations of the SDSS galaxy located inside
the XRT error circle of GRB 090417B (GCNs 9153, 9155, 9140) with GMOS on
the Gemini-North telescope. In a combined 1800 sec spectrum we detect
emission lines corresponding to [OII]3727, [OIII]5006, and H-alpha at a
redshift of z=0.345. At this redshift the observed fluence of the burst
(2.3e-6 erg/cm^2; GCN 9139) translates to an isotropic-equivalent energy
of 9e50 erg."
GCN Circular 9158
Subject
GRB 090417B: Gemini imaging
Date
2009-04-18T18:54:50Z (16 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
E. Berger (Harvard), D.B. Fox (PSU), and N. Tanvir (Leicester) report:
"In addition to the spectroscopic observations described in GCN 9156, we
also imaged the field of GRB 090417B with GMOS in the griz filters
starting on 2008 April 18.38 (17.7 hours after the burst). A total of 360
sec were obtained in gri, and a total of 540 sec was obtained in z. We
find the following magnitudes for the SDSS galaxy coincident with the XRT
afterglow position:
g = 22.47+/-0.16 mag (SDSS: 23.0+/-0.5 mag)
r = 21.62+/-0.10 mag (SDSS: 21.62+/-0.16 mag)
i = 21.31+/-0.12 mag (SDSS: 21.41+/-0.09 mag)
z = 21.49+/-0.30 mag (SDSS: 20.78+/-0.25 mag)
Thus, we find no evidence for brightening compared to the SDSS archival
magnitudes."
GCN Circular 9165
Subject
VLA radio upper limit on GRB 090417B
Date
2009-04-19T23:26:11Z (16 years ago)
From
Poonam Chandra at U Virginia/NRAO <pc8s@virginia.edu>
Poonam Chandra (RMC) and Dale A. Frail (NRAO) report on
behalf of a larger collaboration:
"We used the Very Large Array to observe the field of view toward
GRB 090417B (GCN 9135) at a frequency of 8.46 GHz on 2009 Apr. 19.37
UT. The GRB radio afterglow is undetected within the Swift-XRt error
circle (GCN 9155). We place the three-sigma upper limit of 120 uJy on
the GRB afterglow.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 9173
Subject
GRB 090417B Correction to the BAT refined analysis position
Date
2009-04-20T17:04:26Z (16 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <jayc@milkyway.gsfc.nasa.gov>
J. R. Cummings (GSFC/UMBC), S. D. Barthelmy, H. A. Krimm (GSFC/USRA),
B. Sbarufatti(INAF-IASFPA), P.A. Evans (U. Leicester)
on behalf of the Swift team
We wish to make a correction to the reported analysis of the
extremely long-duration burst GRB 090417B (GCN circ #9135,
Sbarufatti et al.).
The position in the BAT refined-analysis circular (GCN circ #9139,
Cummings et al.) was based on the results of an automated script,
which was unable to find the optimum imaging interval due to the
unusual length of this burst. Thus the reported position was not
the best BAT ground-calculated position. The best position is
RA, Dec 209.687 +47.015, which is:
RA (J2000) 13h 58m 44.8s
Dec (J2000) 47d 00m 55s
with an error radius of ~1 arcmin. This position is 0.35 arcmin
from the XRT refined position (GCN circ #9155, Sbarufatti et al.).
We are grateful to those who noticed the discrepancy, and regret
any confusion resulting from this error. Any corrections to other
BAT refined-analysis items (which are expected to be slight), such
as to the spectral index, will appear in the final Swift Team
report on this burst.
GCN Circular 9174
Subject
GRB 090417B: Swift/UVOT Upper Limits
Date
2009-04-20T19:46:26Z (16 years ago)
From
Stephen Holland at USRA/NASA/GSFC/SSC <Stephen.T.Holland@nasa.gov>
S. T. Holland (CRESST/GSFC/USRA) and B. Sbarufatti (INAF-IASFPA)
report on the behalf of the Swift UVOT team:
The Swift/UVOT observed the field of GRB 090417B starting 378 s
after the BAT trigger (Sbarufatti, et al., 2009, GCN Circ. 9135).
Settled exposures started at T+395 s. We do not find any new source,
relative to the DSS, USNO-B1.0, or 2MASS at the position of the XRT
afterglow (Sbarufatti, et al. 2009, GCN Circ. 9155). Preliminary
3-sigma upper limits for detecting a source in the white finding
chart, and the co-added images, using a 2.5 arcsecond radius circular
aperture, are
Filter T_start T_stop Exp(s) Mag
--------------------------------------------
white (fc) 395 545 147 >21.7
v 552 13,098 1237 >21.3
b 651 19,457 862 >21.9
u 1300 25,241 1376 >22.0
uvw1 601 25,174 2300 >22.2
uvm2 750 24,268 1878 >21.8
uvw2 700 29,604 1331 >22.0
white 395 7823 841 >22.6
--------------------------------------------
The quoted upper limits have not been corrected for the expected
Galactic extinction along the line of sight corresponding to a
reddening of E_{B-V} = 0.02 mag (Schlegel, et al., 1998, ApJS, 500,
525). All photometry is on the UVOT photometry system described in
Poole et al. (2008, MNRAS, 383, 627).
GCN Circular 9180
Subject
GRB 090417B: Optical observation
Date
2009-04-21T04:28:00Z (16 years ago)
From
Rupak Roy at ARIES <rupakroy1980@gmail.com>
Brajesh Kumar, Rupak Roy, Brijesh Kumar and S. B. Pandey (ARIES, NainiTal,
India, on behalf
of larger Indian GRB collaboration).
We observed swift GRB 090417B (GCN 9135) using 104 cm Sampurnanand optical
telescope
at A.R.I.E.S. Nainital on 17th April, 2009 at 16.244 hrs UT, under good sky
conditions using
2k*2k CCD detector.
No afterglow candidate was found in our co-added R_c band image (exp time =
5*300 sec)
within the error region of BAT. Photometry of the stacked frame poses an
upper limit of
~ 21 mag, in comparison to nearby USNO-B1 stars.