GRB 090817
GCN Circular 9815
Subject
GRB 090817: a long GRB localized by INTEGRAL
Date
2009-08-17T02:53:44Z (16 years ago)
From
Volker Beckmann at ISDC <Volker.Beckmann@obs.unige.ch>
V.Beckmann (ISDC, Versoix), D.Gotz (CEA-Saclay), S.Mereghetti,
A.Paizis (IASF-Milano), A. Neronov, M. Beck (ISDC, Versoix), and J.
Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report:
A long GRB with duration of about 250 s has been detected by IBAS in
IBIS/ISGRI data at 00:51:33 UT on August 17th.
The refined coordinates (J2000) are:
RA: 63.9659 [degrees]
DEC: +44.1234 [degrees]
with an uncertainty of 2.6 arcmin (90% c.l.).
The light curve shows two prominent peaks at T0 and at T0+196s. A plot
of the light curve will be posted at
http://ibas.iasf-milano.inaf.it/IBAS_Results.html
This message can be cited.
GCN Circular 9819
Subject
GRB 090817: Swift-XRT observations
Date
2009-08-17T13:59:42Z (16 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
P.A. Evans (U. Leicester), C. Guidorzi (U Ferrara) and W.H. Baumgartner
(GSFC/UMBC) report on behalf of the Swift-XRT team:
The Swift-XRT observed the field of GRB 090817 (Beckmann et al. GCN
Circ. 9815) from T0+11 ks to T0+17.5 ks gathering 1.8 ks of Photon
Counting (PC) mode data.
Inside the INTEGRAL error circle we find a single, uncatalogued X-ray
source at RA, Dec = 63.96600, 44.12900 which is equivalent to:
RA (J2000): 04 15 51.85
Dec (J2000): +44 07 44.5
with an uncertainty of 2.0 arcsec (radius, 90% confidence). The optical
source USNO-B1.0 1341-0096763 lies only 1.3 arcsec from the XRT
position. This object is point-like in USNO-B1, with magnitudes I=18.5,
R=20.0, B=20.8.
The light curve of the X-ray source shows a rapid rise from 0.04 ct/sec
at T0+11 ks to 0.1 ct s^-1 at T0+12 ks; by T0+18 ks the count rate has
returned to 0.04 ct s^-1. A spectrum formed from the PC mode data can
be modelled with an absorbed power law with a photon index of 2.5 (+0.7,
-0.6) with an absorption column of 9.5 (+4.9, -4.0) x 10^21 cm^-2, in
excess of the Galactic value of 4.0 x 10^21 cm^-2 (Kalberla et al.
2005).
Given the light curve of this source, it is not clear whether or not
this is a GRB afterglow. A further observation has therefore been
planned, and will take place today.
No other sources are detected in the INTEGRAL error circle, with a
3-sigma upper limit of 5 x 10^-3 ct s^-1. Using the typical
counts-to-observed-flux conversion factor from Evans et al (2009, MNRAS,
397, 1177) this gives a flux limit of 1.7 x 10^-13 erg cm^-2 s^1.
This circular is an official product of the Swift-XRT team.
--
-------------------------
Phil Evans,
Swift Development Scientist
X-ray and Observational Astronomy Group,
University of Leicester
Tel: (0116) 252 5059
pae9@star.le.ac.uk
http://www.star.le.ac.uk/~pae9
GCN Circular 9822
Subject
GRB 090817: Swift/UVOT Upper Limits
Date
2009-08-17T15:58:28Z (16 years ago)
From
Alice Breeveld at MSSL-UCL <aab@mssl.ucl.ac.uk>
A. Breeveld (MSSL/UCL) and W. Baumgartner (GSFC) report on behalf of
the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 090817
11008 s after the INTEGRAL trigger (Beckmann et al., GCN Circ. 9815).
No new sources are found in the UVOT data at the position of the XRT
source (P.A. Evans et al., GCN Circ. 9819). Preliminary 3-sigma upper
limits using the UVOT photometric system (Poole et al. 2008, MNRAS,
383, 627) and a 3 arcsec radius aperture, for the initial summed
exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 11516 17719 413 >21.3
v 11975 12398 416 >19.6
b 11058 17509 787 >21.2
u 11008 17157 78 >19.5
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.66 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 9823
Subject
GRB 090817: Fermi GBM observation
Date
2009-08-17T18:23:30Z (16 years ago)
From
Colleen A. Wilson at NASA/MSFC/NSSTC <colleen.wilson@nasa.gov>
Colleen A. Wilson-Hodge (NASA/MSFC)
reports on behalf of the Fermi GBM Team:
"At 00:51:26.21 UT on 17 August 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090817 (trigger 272163088 / 090817036).
which was also detected by INTEGRAL (Beckmann et al. 2009, GCN 9815)
The GBM on-ground location is consistent with the INTEGRAL position.
The angle from the Fermi LAT boresight is 82 degrees.
The GBM light curve consists of an initial bright peak at the trigger time
followed by a weak broad bump about 200 s after the trigger. This burst has
a duration (T90) of about 220 s (8-1000 keV).
Spectral analysis was performed only for the bright initial peak. The
time-averaged spectrum from T0 to T0+41 s is adequately fit by a Band
function with Epeak = 115 +/- 50 keV, alpha = -1.1 +/- 0.3, and
beta = -2.2 +/- 0.6
The event fluence (8-1000 keV) over the T90 interval is
(7.3 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.15 s in the 8-1000 keV band
is 3.8 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 9825
Subject
GRB 090817: Confirmation of the X-ray afterglow
Date
2009-08-18T08:52:01Z (16 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans (U. Leicester), C. Guidorzi (U Ferrara) and W.H. Baumgartner
(GSFC/UMBC) report on behalf of the Swift-XRT team:
Swift conducted a second observation of GRB 090817 (Beckmann et al. GCN
Circ. 9815), collecting 3.9 ks of Photon Counting (PC) mode XRT data in
the interval T0+50 ks to T0+58 ks. The source reported by Evans et al.
(GCN Circ. 9819) has faded to a level of ~0.015 ct s^-1. A power-law fit
to the light curve yields a temporal decay index of alpha=0.9+/-0.2
Inspecting the USNO-B1 catalogue within 3.5' of the GRB we find 216
objects with R2<20.0. The probability of finding a USNO-B1 source within
a 2" radius circle in this field is thus 2%. The strength of the
potential association between the XRT and USNO-B1 sources noted in GCN
Circ. 9819 is therefore fairly weak.
We therefore suggest that the XRT source is the afterglow of GRB 090817.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020108.
This circular is an official product of the Swift-XRT team.
GCN Circular 9826
Subject
GRB 090817: optical upper limit
Date
2009-08-18T12:02:36Z (16 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev (CrAO), A. Pozanenko (IKI), M. Andreev (Terskol Branch of
Institute of Astronomy) report on behalf of larger GRB follow-up
collaboration:
We observed a field of the INTEGRAL GRB 090817 (Beckmann et al., GCN 9815)
with Shajn telescope of CrAO starting on Aug. 17 (UT) 01:07, i.e. ~17
minutes after burst onset. A series of 37 images of 60 s exposure was
obtained in R filter. Within XRT error circle of the afterglow (Evans et
al., GCN 9819, GCN 9825) we do not detect any new object. The quoted
USNO-B1.0 star USNO-B1.0 1341-0096763 (Evans et al., GCN 9819) does not
change its brightness within ~0.08 m during our observations. An upper limit
of a single frame of 60 s exposure is R~21.5 m. Data reduction is
continuing.
GCN Circular 9827
Subject
GRB 090817: Liverpool Telescope Observations
Date
2009-08-18T18:56:21Z (16 years ago)
From
Zach Cano at ARI/John Moores Liverpool <zec@astro.livjm.ac.uk>
GRB 090817: Liverpool Telescope Observations
Z. Cano, I.A. Steele, C.G. Mundell, A. Melandri, S. Kobayashi, C.J.
Mottram, R.J. Smith, D. Bersier (Liverpool JMU), A. Gomboc (U. Ljubljana),
report on behalf of a large collaboration:
On August 17 2009, 1.459 hours after the burst was detected, the 2-m
Liverpool Telescope automatically began observing the INTEGRAL GRB 090817
(Beckmann et al.,GCN Circ. 9815) using g',r' and i' filters.
We do not detect any uncatalogued source inside the Swift-XRT error circle
(Evans et al. GCN Circ 9819). Upper limits in stacked R and I images for
isolated objects are 20.6 and 20.8 respectively.
Magnitudes have been calibrated from the nearby USNO star (1341-0096766):
04:15:52.314, +44:07:50.9 using R2=17.56 and I=17.04.
We note that the upper limits presented are the limits for detecting an
isolated object in our images. As the USNO star (1341-0096763) lies only
1.3" from the XRT position the actual upper limits will be accordingly
brighter.
GCN Circular 9828
Subject
GRB 090817: aphotometry of USNO-B1.0 341-0096763
Date
2009-08-19T21:51:06Z (16 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev (CrAO), A. Pozanenko (IKI), M. Andreev (Terskol Branch of
Institute of Astronomy) report on behalf of larger GRB follow-up
collaboration:
We report a photometry of the USNO-B1.0 object 341-0096763 in the XRT error
circle of the X-ray afterglow (Evans et al., GCN 9819, GCN 9825) of the
INTEGRAL GRB 090817 (Beckmann et al., GCN 9815). The observations took
place with Shajn telescope of CrAO on Aug.17 (Rumyantsev et al., GCN
9826). The photometry is based on the reference star USNO B1.0 1341-0096766
(04 15 48.35 +44 08 07.7) assuming R = 17.54, only statistical errors are
quoted. Upper limits are presented for isolated object. To make any
conclusion about variability of the star or the presence in the tail of the
star other possible source we are planning second epoch observation.
Date Time start (UT) Upper_Limit R_mag
2009-08-17 01 09 36.45 21.5 19.33 +/-0.05
2009-08-17 01 10 40.62 21.5 19.38 +/-0.05
2009-08-17 01 13 23.49 21.7 19.43 +/-0.04
2009-08-17 01 14 27.16 21.7 19.32 +/-0.04
2009-08-17 01 15 30.91 21.8 19.35 +/-0.04
2009-08-17 01 16 34.72 21.9 19.46 +/-0.04
2009-08-17 01 17 38.27 21.9 19.40 +/-0.04
2009-08-17 01 18 41.93 21.9 19.44 +/-0.04
2009-08-17 01 19 45.99 21.7 19.39 +/-0.04
2009-08-17 01 20 49.53 21.7 19.37 +/-0.04
2009-08-17 01 21 53.11 21.8 19.45 +/-0.04
2009-08-17 01 22 58.16 21.7 19.40 +/-0.04
2009-08-17 01 24 01.75 21.8 19.28 +/-0.04
2009-08-17 01 25 05.64 21.8 19.45 +/-0.04
2009-08-17 01 26 09.20 21.8 19.46 +/-0.04
2009-08-17 01 27 12.86 21.8 19.39 +/-0.04
2009-08-17 01 28 16.41 21.8 19.38 +/-0.04
2009-08-17 01 29 22.52 21.6 19.38 +/-0.05
2009-08-17 01 30 26.12 21.6 19.39 +/-0.05
2009-08-17 01 31 29.63 21.6 19.38 +/-0.05
2009-08-17 01 32 33.37 21.7 19.33 +/-0.04
2009-08-17 01 33 38.37 21.6 19.39 +/-0.05
2009-08-17 01 34 42.08 21.6 19.38 +/-0.05
2009-08-17 01 35 45.77 21.6 19.42 +/-0.05
2009-08-17 01 36 49.51 21.5 19.46 +/-0.06
2009-08-17 01 37 53.18 21.4 19.34 +/-0.05
2009-08-17 01 38 56.70 21.3 19.55 +/-0.08
2009-08-17 01 40 00.31 21.3 19.44 +/-0.07
2009-08-17 01 41 06.39 21.2 19.30 +/-0.07
2009-08-17 01 42 12.89 21.2 19.47 +/-0.08
2009-08-17 01 43 16.53 21.1 19.41 +/-0.08
2009-08-17 01 44 20.34 21.1 19.43 +/-0.08
2009-08-17 01 45 24.13 20.9 19.41 +/-0.10
2009-08-17 01 46 28.68 20.9 19.42 +/-0.10
2009-08-17 01 47 32.26 20.7 19.29 +/-0.11
2009-08-17 01 48 35.81 20.7 19.52 +/-0.13
GCN Circular 9831
Subject
GRB 090817: Swift/UVOT Observations of a Host Galaxy Candidate
Date
2009-08-20T19:17:42Z (16 years ago)
From
Stephen Holland at USRA/NASA/GSFC/SSC <Stephen.T.Holland@nasa.gov>
S. T. Holland (CRESST/GSFC/USRA), A. Breeveld (MSSL/UCL), and
W. Baumgartner (GSFC/UMBC) report on behalf of the Swift UVOT team:
The Swift/UVOT observed the field of GRB 090817 (Beckman et al.,
2009, GCN Circ. 9815) between 11 ks and 284 ks after the INTEGRAL
trigger. The USNO-B1.0 source 1341-0096763 (Evans et al. 2009, GCN
Circ. 9819, Rumyantsev et al. 2009, GCN Circ. 9828) is detected inside
the XRT error circle (Evans et al., 2009, GCN Circ. 9819). We find no
evidence for variability in this source during our observations.
Preliminary
magnitudes and 3-sigma upper limits from all of the coadded data are
Filter Exposure Mag Err Sigma
--------------------------------------
v 416 19.86 0.46 2.4
b 787 20.99 0.33 3.4
u 4003 21.49 0.30 3.7
uvw1 4326 >22.0 ... ...
white 413 21.19 0.37 3.2
The quoted magnitudes and upper limits have not been corrected for the
expected Galactic extinction along the line of sight corresponding to
a reddening of E_{B-V} = 0.66 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).
The UVOT coordinates of this source are
RA (J2000.0) 04:15:51.85 = 63.96604 (deg)
Dec (J2000.0) +44:07:44.5 = +44.12902 (deg)
with an estimated uncertainty of 1.0 arcsec (radius, 90% confidence,
statistical + systematic). The dereddened colours of the source are
not consistent with a stellar spectrum. However, the colours are
consistent with an Sm or Im galaxy (de Vaucouleurs, 1961, ApJS, 5,
233). This suggests that the source may be the host galaxy of GRB
090817. If this galaxy has an absolute magnitude similar to that of
the LMC then it is located at a redshift of approximately z = 0.05.
An intrinsically fainter galaxy would be closer. Follow-up
spectroscopy is encouraged to verify this.
GCN Circular 9834
Subject
GRB 090817: Swift/UVOT Observations of a Possible Late-Time Brightening
Date
2009-08-24T18:58:29Z (16 years ago)
From
Stephen Holland at USRA/NASA/GSFC/SSC <Stephen.T.Holland@nasa.gov>
S. T. Holland (CRESST/GSFC/USRA), A. Breeveld (MSSL/UCL), and
W. Baumgartner (GSFC/UMBC) report on behalf of the Swift UVOT team:
Swift/UVOT observed the USNO-B1.0 source 1341-0096763 (Evans et
al. 2009, GCN Circ. 9819; Rumyantsev et al. 2009, GCN Circ. 9828;
Holland et al. 2009, GCN Circ. 9831), which is located inside the XRT
error circle (Evans et al., 2009, GCN Circ. 9819), at approximately 6
and 7 days after the INTEGRAL trigger (Beckman et al., 2009, GCN
Circ. 9815). A preliminary examination of the UVOT data yields weak
evidence that the source may have brightened by approximately 0.5 mag
in the UVOT v band between approximately 6.5 and 7.1 days. Our
observations are consistent with a supernova rising to maximum light.
However, we stress that further observations are needed to confirm
this. Follow-up photometric and spectroscopic observations of this
source are strongly encouraged.
GCN Circular 9837
Subject
GRB 090817: No host galaxy, no supernova
Date
2009-08-25T11:16:13Z (16 years ago)
From
Jules Halpern at Columbia U. <jules@astro.columbia.edu>
J. P. Halpern and J. Ruan (Columbia U.) report:
We obtained R-band photometry of the USNO-B1.0 object 341-0096763
on 2009 August 21 10:46 UT using the McGraw Hill 1.3m telescope.
In five 300 s exposures in seeing of 1.5"-1.8", there is no evidence
to support the hypothesis of Holland et al. (GCN Circ. 9831) that this
object is the host galaxy of GRB 090817. The image is consistent
with the stellar point spread function. Using the reference star of
Rumyantsev et al. (GCN Circ. 9828), we measure R = 19.39+/-0.04,
consistent with their photometry on Aug. 17.
On Aug. 25 09:56 UT, we again obtained five 300 s exposures in seeing
of 1.5". We measure R = 19.42+/-0.03, 8.4 days after the burst,
which is consistent with all previous measurements. Thus, there is
no evidence for brightening suggested by Holland et al. (GCN Circ. 9834)
from Swift UVOT observations between 6.5 and 7.1 days. The set of
consistent magnitudes from day zero in GCN Circ. 9828 to days 4 and 8
in this report are indicative of a chance coincidence with a normal star.
GCN Circular 9841
Subject
GRB090817: Keck/LRIS Spectroscopy
Date
2009-08-26T08:22:47Z (16 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. B. Cenko, L. M. Walkowicz (UC Berkeley), M. M. Kasliwal, V. Bhalero, S.
R. Kulkarni, F. A. Harrison (Caltech), I. Arcavi (Weizmann Institute) and
W. H. Baumgartner (GSFC/UMBC) report on behalf of a larger collaboration:
We have obtained a spectrum of the putative host galaxy of GRB09817
(Holland et al., GCNs 9831 and 9834) with the Low Resolution Imaging
Spectrometer mounted on the 10 m Keck I telescope. Our spectra were taken
in twilight conditions at Aug 25.55 UT and cover a wavelength range from
3500 - 9000 A.
After correcting for the large Galactic extinction, the source exhibits
a blue continuum with superposed absorption features from the H Balmer
series (H-alpha, -beta, -gamma, and -delta) and Ca (H+K and the NIR
triplet), all consistent with their rest wavelengths. As suggested by
Halpern and Ruan (GCN 9837), the object is therefore a foreground star
(likely a hot, ~ A-type) and likely unrelated to GRB090817.
GCN Circular 9842
Subject
GRB 090817 - TLS Observations
Date
2009-08-27T00:27:50Z (16 years ago)
From
Alexander Kann at TLS Tautenburg <kann@tls-tautenburg.de>
D. A. Kann, F. Cusano and F. Ludwig (TLS Tautenburg) report:
We observed the field of the INTEGRAL/Fermi GRB 090817 (Beckmann et al.,
GCN 9815, Wilson-Hodge, GCN 9823) with the 1.34m Tautenburg Schmidt
telescope under good conditions. We obtained 3 x 600 sec Rc images at a
mid-time of 8.015 days after the GRB.
At the position of the X-ray afterglow (Evans, Guidorzi & Baumgartner,
GCN 9819, GCN 9825), the USNO-B1.0 object 1341-0096763 is clearly
detected. Using the comparison star of Rumyantsev, Pozanenko & Andreev
(GCN 9828), we find Rc = 19.54 +/- 0.03 mag. This is in agreement
with the reports of non-variability (Rumyantsev, Pozanenko & Andreev,
GCN 9828, Halpern & Ruan, GCN 9837) of this proposed host galaxy/SN
candidate (Holland, Breeveld & Baumgartner, GCN 9831, GCN 9834), and a
stellar PSF is in full agreement with it being a foreground star (Halpern
& Ruan, GCN 9837, Cenko et al., GCN 9841).
No further observations are planned.
This message may be cited.