GRB 091003
GCN Circular 9986
Subject
GRB 091003: Swift XRT analysis
Date
2009-10-04T00:44:01Z (16 years ago)
From
Rhaana Starling at U of Leicester <rlcs1@star.le.ac.uk>
R.L.C. Starling and A.P. Beardmore (U. Leicester) report on behalf
of the Swift-XRT team:
The Swift X-ray Telescope (XRT) observed the Fermi GBM/LAT and
Integral-detected GRB 091003 (Rau GCN Circ. 9983; McEnery et al. GCN
Circ. 9985) on 2009 October 3 at 20:07:28 UT, 15.5 hours after the
Fermi trigger.
In 2.5 ks of photon counting mode data we detect an uncatalogued
X-ray source at RA, Dec = 251.52047, 36.62548 degrees, which is
equivalent to:
RA (J2000) = 16:46:04.9
Dec (J2000) = +36:37:31.74
with an uncertainty of 3.7 arcsec (radius, 90% containment). This
is 6.85 arcmin from the Fermi LAT position and within its error circle.
A spectrum formed from these data can be fit with an absorbed power law of
photon index 1.7+/-0.3, with nH < 2e21 cm-2, and has an observed 0.3-10 keV
count rate of 0.087+/-0.007 count/s corresponding to a flux of 3.6e-12
erg/cm2/s.
At this stage we do not have enough data to tell if the source is fading.
This circular is an official product of the Swift-XRT team.
GCN Circular 9987
Subject
GRB 091003: Swift UVOT Detection of a Candidate UV Afterglow
Date
2009-10-04T02:21:18Z (16 years ago)
From
Caryl Gronwall at PSU/Swift-UVOT <caryl@astro.psu.edu>
C. Gronwall (PSU) and R.L.C. Starling (U. Leicester) report on behalf
of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 091003
approximately 15.5 hours after the Fermi/GBM trigger (Rau,
GCN Circ. 9983). In a 885 sec observation in the uvw2 filter, we
find a faint candidate fading UV afterglow within the XRT error circle
(Starling & Beardmore, GCN Circ. 9986). The estimated magnitude is
21.02 +/- 0.27. This value is not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.02 in the direction of
the burst (Schlegel et al. 1998).
GCN Circular 9988
Subject
GRB 091003: UVOT-enhanced XRT position
Date
2009-10-04T12:10:23Z (16 years ago)
From
Rhaana Starling at U of Leicester <rlcs1@star.le.ac.uk>
R.L.C. Starling, P.A. Evans, A.P. Beardmore and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team:
Using 4881 s of XRT Photon Counting mode data and 11 UVOT
images for GRB 091003, 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 =
251.51980, 36.62470 which is equivalent to:
RA (J2000): 16 46 4.75
Dec (J2000): +36 37 29.0
with an uncertainty of 1.7 arcsec (radius, 90% confidence). The UV
counterpart reported in Gronwall & Starling (GCN Circ.9987) is consistent
with this position.
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 is an official product of the Swift-XRT team.
GCN Circular 9989
Subject
GRB 091003: Skynet/DSO Observations
Date
2009-10-04T18:14:15Z (16 years ago)
From
Josh Haislip at U.North Carolina <haislip@physics.unc.edu>
J. Haislip, D. Reichart, A. Smith, D. Caton, L. Hawkins, K. Ivarsen, A.
LaCluyze, A. Foster, J. Moore, A. Oza, M. Schubel, J. Styblova, A. Trotter,
J. A. Crain, and M. Nysewander report:
Skynet observed the Fermi/LAT localization (McEnery, Chiang & Hanabata, GCN
9985) of GRB 091003 (Rau, GCN 9935) with the 14" Dark Sky Observatory
telescope in North Carolina beginning 20.2 hours after the trigger in BVRI.
We do not detect the afterglow (Starling & Beardmore, GCN 9986; Gronwall &
Starling, GCN 9987). Stacking only images that increase the limiting
magnitude yields:
mean 1-sig. 1-sig.
time 3-sig. sys. stat.
since lim. cal. cal. cal.
trig. tel. exp. fil. mag. stars* unc. unc.
(h) (# x s) (mag) (mag)
21.0 DSO-14 16 x 80 V 19.6 58 SDSS 7 0.076 0.000
21.0 DSO-14 17 x 80 B 19.5 33 SDSS 7 0.087 0.001
21.0 DSO-14 16 x 80 R 19.8 64 SDSS 7 0.064 0.000
21.0 DSO-14 16 x 80 I 19.3 45 SDSS 7 0.049 0.000
* Transformed using Jester et al., 2005, ApJ, 130, 873.
GCN Circular 9990
Subject
GRB 091003: Swift/UVOT Detection of an Optical Afterglow
Date
2009-10-04T23:42:48Z (16 years ago)
From
Tyler Pritchard at PSU <tapritchard@astro.psu.edu>
T. A. Pritchard (PSU) , E.A. Hoversten (PSU), and
R.L.C. Starling (U. Leicester) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began settled observations of the field of
GRB 091003 approximately 15.5 hours after the FERMI/GBM Trigger (Rau,
GCN Circ. 9983) A faint source is detected with 3.9-sigma confidence
in the summed UVOT observations at the Swift UVOT-enhanced XRT
position (R.L.C. Starling, et al. GCN Circ. 9988).
The observed magnitudes and upper limits using the UVOT photometric
system (Poole etal. 2008, MNRAS, 383, 627) for the initial exposures
are:
Filter T_start(s) T_stop(s) Exp(s) Mag
=======================================================================
w2 56820 64169 1150 21.08 � 0.28 (3.9 sigma)
w1 103712 104474 750 20.70 � 0.32 (3.4 sigma)
b 92252 92954 685 20.80 � 0.26 (4.1 sigma)
m2 98013 98715 691 > 21.63
v 86432 87195 741 > 20.27
The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 9991
Subject
GRB 091003: Swift-XRT confirmation of fading afterglow
Date
2009-10-05T07:59:40Z (16 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
K.L. Page, R.L.C. Starling, P.A. Evans & A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team:
We have now collected 15 ks of Swift-XRT Photon Counting mode data on the
Fermi burst GRB 091003 (Rau, GCN Circ. 9983; McEnery, Chiang & Hanabata,
GCN Circ. 9985), between 56 and 168 ks after the trigger. The light-curve
is fading, with alpha = 1.02 +0.21/-0.20. We therefore confirm that the
source given by Starling et al. in GCN Circ. 9986 and 9988 is, indeed, the
X-ray afterglow.
This circular is an official product of the Swift-XRT team.
GCN Circular 9995
Subject
GRB 091003: WHT ACAM observations
Date
2009-10-05T17:11:44Z (16 years ago)
From
Klaas Wiersema at U of Leicester <kw113@star.le.ac.uk>
K. Wiersema, N. Tanvir (Leicester), A. Levan (Warwick) and C. Benn (ING)
report on behalf of a larger collaboration:
We observed the afterglow of Fermi GRB 091003 (Rau GCN 9983; McEnery et al
GCN 9985; Starling & Beardmore GCN 9986) with the William Herschel
Telescope, using the ACAM instrument. We took a 60 and a 250 second
exposure in imaging mode, starting at 21:11 UT, October 4 (1.69 days after
burst).
The afterglow is clearly detected, with r = 21.33 +/- 0.11 (calibrated to
SDSS field stars), at position:
RA (J2000) = 16:46:04.687
Dec (J2000) = +36:37:30.76
with uncertainty 0.3 arcseconds.
We obtained spectroscopy with ACAM immediately after, at high airmass. Two
900 second exposures were obtained using the 400V grism and a 1 arcsecond
slit. Faint continuum emission is detected over the 4000-9300 A range. No
strong absorption or emission lines are detected. The detection of
continuum at 4000A gives a upper limit to the redshift of 2.3.
GCN Circular 9997
Subject
GRB 091003: Lick observations and possible SDSS host galaxy
Date
2009-10-06T22:17:22Z (16 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, J. Choi, A. J. L. Morton, and M. Ganeshalingam (UC
Berkeley) report:
We observed the position of Fermi GRB 091003 (Rau et al., GCN9983) using
the Nickel 1m telescope at Lick Observatory on the night of 2009-10-06
(UT) starting at 04:06 for a series of five 600-second exposures in
R-band. The afterglow (Starling and Beardmore, GCN 9986; Gronwall and
Starling, GCN 9987) is marginally detected in the combined frame.
Calibrating to nearby SDSS stars transformed to R-band using the
equations of Lupton et al. (2005) we estimate a magnitude of
R = 21.2 +/- 0.4 (t_mid = 3.00 days)
This suggests only limited fading since the observations of Wiersama et
al. (GCN 9995).
Further, we note that a source coincident with this position is detected
in the SDSS survey imaging. The object (SDSS J164604.70+363731.1) has a
magnitude of r = 23.2 and is classified as a star, but could represent
the host galaxy of this event. A low redshift would also be consistent
with the absence of absorption signatures in the spectrum of Wiersema et
al. and with the Swift UVW2 detection (Pritchard et al., GCN 9990). We
encourage further observations, in particular additional spectroscopy,
of this object.
GCN Circular 10031
Subject
GRB 091003: Gemini-N redshift of possible host galaxy
Date
2009-10-18T19:20:08Z (16 years ago)
From
Antonino Cucchiara at PSU <cucchiara@astro.psu.edu>
A. Cucchiara, D. B. Fox (PSU), S. B. Cenko (U. Berkeley), N. Tanvir (U.
Leicester),
E. Berger (Harvard U.) report on behalf of a larger collaboration:
"On October 17.20 UT we observed the possible host galaxy of the Fermi/LAT
GRB 091003 (McEnery at al, GCN 9985 and Perley et al. GCN 9997) with
Gemini GMOS-N.
We took a sequence of 2 spectra of 1800s each covering the 6000-10000A
wavelength range. The spectra clearly show emission lines which we
interpreted
as [OII]3727, Hbeta and we resolved the [OIII]4959,5007 doublet.
All these identifications are consistent with redshift z = 0.8969 for
this galaxy.
The galaxy is detected in our 300s R-band acquisition image.
The estimated magnitude, calibrated using 3 SDSS stars is:
R = 22.65 +- 0.05 mag
This value is brighter than the cataloged magnitude, which may indicate a
contribution of the afterglow. After subtracting the contribution
of the galaxy we derive an estimate of the OT flux, R = 23.65 +- 0.05 mag.
We thank the Gemini staff for performing these observations."
GCN Circular 10032
Subject
GRB 091003: Possible Supernova Component
Date
2009-10-18T19:56:31Z (16 years ago)
From
Stephen Holland at USRA/NASA/GSFC/SSC <Stephen.T.Holland@nasa.gov>
S. T. Holland (CRESST/USRA/GSFC) reports:
The excess light from the z = 0.8969 host galaxy candidate for
GRB 091003 (Cucchiara et al. 2009, GCNC 10031) correspond to a
rest-frame B-band absolute magnitude of approximately M_B = -20 mag.
This is approximately consistent with the peak rest-frame B-band
absolute magnitude of SN1998bw. The Cucchiara et al. (2009, GCNC
10031) observation was taken on 2009 Oct 17, which corresponds to
approximately seven days after the burst in the rest frame, which is
approximately the expected time of maximum light for a SN Ib/c.
Therefore, we suggest that the excess light seen in this galaxy may be
due to a supernova component of GRB 091003. The lack of an observed
optical afterglow at earlier times supports this interpretation.
Further spectroscopic observations are encouraged to test this
hypothesis.
GCN Circular 10033
Subject
Fwd: GRB 091003: Possible Supernova Component Retraction
Date
2009-10-18T20:04:51Z (16 years ago)
From
Stephen Holland at USRA/NASA/GSFC/SSC <Stephen.T.Holland@nasa.gov>
S. T. Holland (CRESST/USRA/GSFC) reports:
I would like to retract GCNC 10032 (Holland 2009). It was sent
in error due to a confusion between GRB 091003 and GRB 091010. I
apologize for the error and any confusion that it may have caused.