GRB 080514B
GCN Circular 7715
Subject
GRB 080514B: SuperAGILE/IPN GRB Localization
Date
2008-05-14T19:06:44Z (17 years ago)
From
Marco Feroci at IASF/INAF <feroci@iasf-roma.inaf.it>
M. Rapisarda, E. Costa, E. Del Monte, I. Donnarumma, Y. Evangelista,
M. Feroci, I. Lapshov, F. Lazzarotto, L. Pacciani, P. Soffitta,
(INAF/IASF Rome), A. Giuliani, S. Vercellone, A. Chen, S. Mereghetti, A.
Pellizzoni, F. Perotti, F. Fornari, M. Fiorini, P. Caraveo
(INAF/IASF Milan), A. Bulgarelli, F. Gianotti, M. Trifoglio,
G. Di Cocco, C. Labanti, F. Fuschino, M. Marisaldi,
M. Galli, (INAF/IASF Bologna), M. Tavani, G. Pucella, F. D'Ammando, V.
Vittorini, A. Argan, A. Trois (INAF/IASF Rome), G. Barbiellini,
F. Longo (INFN Trieste), P. Cattaneo (INFN Pavia), P. Picozza,
A. Morselli (INFN Roma-2), M. Prest, E. Vallazza (Universita`
dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), and P. Giommi, C.
Pittori, B. Preger, F. Verrecchia (ASDC) and L. Salotti (ASI),
on behalf of the AGILE Team,
K. Hurley,
on behalf of the Mars Odyssey team,
I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team, and
W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on
behalf of the GRS-Odyssey GRB team,
report:
"SuperAGILE and AGILE/MCAL detected a gamma ray burst on
May 14th, at 09:55:56 UT. The event was localized by SuperAGILE
at approximately 38 degrees off axis, in the one-dimensional portion of
its field of view, thus providing a narrow and long error box.
The narrow side is 6 arcmin wide, while the long side is approximately 40
degrees wide. In the 20-60 keV energy range the event had a 10s duration,
with a multi-peaked structure.
The same event was also detected by Mars Odyssey. The IPN was
thus able to reduce the SuperAGILE error box to the 100 sq arcmin
error box whose corners are given by the following
coordinates (RA, Dec):
322.962 (21h 31m 50.81s) 0.733 (0d 43m 59.69s)
322.774 (21h 31m 5.74s) 0.667 (0d 40m 2.78s)
322.867 (21h 31m 27.99s) 0.806 (0d 48m 21.16s)
322.678 (21h 30m 42.80s) 0.740 (0d 44m 23.63s)
The centroid of the error box is at (RA, Dec)= (322.820, 0.737)
and the maximal distance between the box corners is 0.283 deg,
that is 16.9 arcmin.
The event occurred in the field of view of the AGILE GRID.
A report on the AGILE/GRID data analysis will follow shortly.
We urge follow-up observations at all wavelengths."
This message may be cited.
GCN Circular 7716
Subject
GRB 080514B: possible AGILE detection at E>50 MeV
Date
2008-05-14T19:13:06Z (17 years ago)
From
Sandro Mereghetti at IASF/CNR <sandro@iasf-milano.inaf.it>
A. Giuliani, F. Fornari, S. Mereghetti, S. Vercellone, A. Chen, A.
Pellizzoni, F. Perotti, M. Fiorini, P. Caraveo, A. Zambra (INAF/IASF
Milan), P. Soffitta, I. Donnarumma, E. Del Monte, M. Feroci, Y.
Evangelista, E. Costa, I. Lapshov, F. Lazzarotto, L. Pacciani, M.
Rapisarda (INAF/IASF Rome), A. Bulgarelli, F. Gianotti, M. Trifoglio, G.
Di Cocco, C. Labanti, F. Fuschino, M. Marisaldi, M. Galli, (INAF/IASF
Bologna), M. Tavani, G. Pucella, F. D'Ammando, V. Vittorini, A. Argan, A.
Trois (INAF/IASF Rome), G. Barbiellini, F. Longo (INFN Trieste), G. De
Paris, P. Picozza, A. Morselli (INFN Roma-2), M. Prest, E. Vallazza
(Universita` dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), and P.
Giommi, C. Pittori, (ASDC) and L. Salotti (ASI), on behalf of the AGILE
Team, report:
"A quick look analysis of the AGILE GRID data of GRB 080514B (Rapisarda et
al. GCN 7715) shows a possible detection at energies E>50 MeV at a
position consistent with the SuperAGILE-IPN localization.
We have requested a ToO observation of the SuperAGILE-IPN error box with
the Swift satellite. We encourage follow-up observations at other
wavelengths."
This message may be cited.
GCN Circular 7718
Subject
GRB 080514B: Watcher observations
Date
2008-05-15T04:33:22Z (17 years ago)
From
Antonio Deugarte at IAA-CSIC <deugarte@iaa.es>
P. Kubanek (IAA-CSIC, GACE), J. French (UCD),
A. de Ugarte Postigo (ESO) report on behalf of a larger
collaboration:
The 0.4m WATCHER telescope located at Boyden Observatory,
South Africa, has observed the field of GRB 080514B (Rapisarda
et al., GCN 7715) starting at May 15.042 UT (~15.1 hours after
the burst) in a sequence of 120s R band exposures. A combined
image covering ~90% of the error box does not show any new
source down to a limiting magnitude of R>19 at a mean epoch of
May 15.076 UT.
Further analysis is ongoing.
GCN Circular 7719
Subject
GRB 080514B: Afterglow candidate
Date
2008-05-15T05:40:09Z (17 years ago)
From
Antonio Deugarte at IAA-CSIC <deugarte@iaa.es>
A de Ugarte Postigo (ESO), A. Castro-Tirado,
J. Gorosabel, M. Jelinek (IAA-CSIC), P. Kubanek
(IAA-CSIC, GACE) A. Garcia, A. Pimienta,
E. Curras (IAC), C. Pereira (Armagh Obs.), on behalf
of a larger collaboration report:
We have observed the error box of GRB080514B (Rapisarda et
al., GCN 7715) from the 0.8m IAC80 telescope at Iza�a Observatory
(Spain) in I-band starting on May 15.133 (17.3 hours after the burst)
There is a source with a mag of I~20.4, not present in the SDSS-i at
the following coordinates (J2000 +/-1"):
R.A.: 21:31:22.69
Dec.: +00:42:28.9
Further observations are encouraged to confirm if this is related to
the GRB.
GCN Circular 7720
Subject
GRB 080514B: Finding chart
Date
2008-05-15T06:14:48Z (17 years ago)
From
Antonio Deugarte at IAA-CSIC <deugarte@iaa.es>
A de Ugarte Postigo (ESO), A. Castro-Tirado,
J. Gorosabel, M. Jelinek (IAA-CSIC), P. Kubanek
(IAA-CSIC, GACE) A. Garc�a, A. Pimienta,
E. Curras (IAC), C. Pereira (Armagh Obs.), on behalf
of a larger collaboration report:
A finding chart of the optical candidate of GRB 080514B
(Rapisarda et al., GCN 7715) reported in GCN 7719,
compared to the SDSS-i frame can be found at:
http://www.sc.eso.org/~adeugart/GRB/080514B/GRB080514B.jpg
GCN Circular 7722
Subject
GRB 080514B, GROND observations
Date
2008-05-15T07:59:26Z (17 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
A. Rossi (Tautenburg), A. Kupcu-Yoldas, J. Greiner (MPE Garching),
S. Klose, R. Filgas (Tautenburg), A. Yoldas, T. Kruehler (MPE), and
G. Szokoly (Eoetvoes Univ. Budapest and MPE)
report on behalf of the GROND team:
We observed the field of GRB 080514B (Rapisarda et al., GCN 7715; Giuliani
et al., GCN 7716) simultaneously in g'r'i'z'JHK using the multi-channel
imager GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m
MPI/ESO telescope on La Silla (Chile). Observations started at 7:03 UT,
about 21 h after the burst.
The afterglow candidate reported by de Ugarte Postigo et al. (GCN 7719) is
detected in g'r'i'z'. Preliminary photometry yields g' = 19.95 +/- 0.2,
calibrated against NOMAD field stars. Observations are ongoing.
We thank Antonio de Ugarte Postigo (ESO) for a rapid communication of the
finding chart.
GCN Circular 7723
Subject
GRB 080514B: Swift-XRT analysis
Date
2008-05-15T08:19:04Z (17 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
K.L. Page, A.P. Beardmore (U. Leicester), S. Mereghetti (INAF - IASF
Milano), M. Feroci and M. Tavani (INAF/IASF Roma) report on behalf of the
Swift-XRT and AGILE teams:
Following a ToO request, Swift-XRT started observing the field of GRB
080514B at 20:12 on 14th May, about 37 ks after the trigger. Within the
SuperAGILE/IPN error box, there are two sources detected, one of which is
much brighter and appears to be fading. We therefore believe this to be
the X-ray afterglow of the GRB.
Using 925 s of overlapping XRT Photon Counting mode and UVOT data, 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 =
322.84426, 0.70843 which is equivalent to:
RA (J2000): 21 31 22.62
Dec (J2000): +00 42 30.3
with an uncertainty of 1.6 arcsec (radius, 90% confidence). This position
is 1.7 arcsec from the i-filter object mentioned by de Ugarte Postigo et
al., in GCN Circ. 7719.
A spectrum of the three orbits of Photon Counting (PC) mode data (6 ks of
data, spanning 37-49 ks after the trigger) can be modelled with an
absorbed power-law of Gamma = 2.06 +0.35/-0.31 and NH = (1.2
+0.8/-0.6)x10^21 cm^-2, which is slightly in excess of the Galactic value
of 3.75x10^20 cm^-2. The observed (unabsorbed) 0.3-10 keV flux is
2.34x10^-12 (3.14x10^-12) erg cm^-2 s^-1. This corresponds to an observed
counts to flux conversion of 1 count = 3.96x10^-11 erg cm^-2.
The light-curve can be fitted with a single power-law, with a slope of
alpha = 1.5 +/- 1.0. If the light-curve continues to follow this decay,
the count rate at 48 hours is predicted to be 6.6x10^-3 count s^-1 (an
observed flux of 2.6x10^-13 erg cm^-2 s^-1).
This circular is an official product of the Swift-XRT team.
GCN Circular 7724
Subject
GRB 080514B: slow fading behaviour ?
Date
2008-05-15T09:35:14Z (17 years ago)
From
Aybuke, Kupcu Yoldas at MPE <ayoldas@mpe.mpg.de>
A. Rossi (Tautenburg), A. Kupcu-Yoldas, J. Greiner (MPE Garching),
S. Klose, R. Filgas (Tautenburg), A. Yoldas, T. Kruehler (MPE), and
G. Szokoly (Eoetvoes Univ. Budapest and MPE)
report on behalf of the GROND team:
We continued observing the field of GRB 080514B (Rapisarda et al.,
GCN 7715; Giuliani
et al., GCN 7716) simultaneously in g'r'i'z'JHK using the multi-channel
imager GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m
MPI/ESO telescope on La Silla (Chile).
We detect a very slow fading behaviour in the afterglow brightness.
The i' band magnitude dropped ~0.05 magnitudes within 1.5 hours,
resulting in i'~20.9 around 08:20 UT. This magnitude is ~0.5
magnitudes fainter than the i-band magnitude given by Ugarte et al.
(GCN 7719).
Please note that the g' magnitude mentioned in GCN 7722 has a typo;
it should be g' = 21.2.
GCN Circular 7725
Subject
GRB 080514B: KPNO 4m IR observations
Date
2008-05-15T11:32:00Z (17 years ago)
From
Adria C. Updike at Clemson U <aupdike@clemson.edu>
Adria C. Updike, Ginger Bryngelson, and Dieter H. Hartmann (Clemson
University) report on behalf of the Clemson GRB Follow-Up Team:
We observed GRB 080514B (Hurley et al., GCN 7715) using the KPNO 4m
telescope and the NEWFIRM NIR imager under decent weather conditions. In
4 min of stacked exposures beginning 24 hours and 20 minutes after the
trigger, we detect the afterglow (Postigo et al., GCN 7719) at J = 19.8
+/- 0.2 (as calibrated to the 2MASS catalog). Observations are ongoing.
This message may be cited.
GCN Circular 7730
Subject
GRB 080514B : redshift estimation
Date
2008-05-15T16:24:56Z (17 years ago)
From
Bruce Gendre at LAM-OAMP <bruce.gendre@oamp.fr>
B. Gendre (LAM/CNRS/Universite de Provence), A. Galli (IASF-Roma/INAF),
M. Bo�r (OHP/CNRS) report :
Using the XRT analysis reported by Page et al. (GCN 7723), we
extrapolated an X-ray flux of 4.8 10^-13 cgi 1 day after the burst (2-10
keV). Using the Boer & Gendre relation, we estimate the redshift of GRB
080514B to be either 2.8 or 0.9 if this event is a group I or II
respectively (see Gendre, Galli & Bo�r, ApJ, in press), with
uncertainties of 30%. Further constraints on the redshift could be set
by B observations of the afterglow candidate reported in de Ugarte
Postigo et al. (GCN 7719).
This message can be cited.
GCN Circular 7734
Subject
GRB 080514B: NOT observations
Date
2008-05-16T06:06:27Z (17 years ago)
From
Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center <malesani@astro.ku.dk>
D. Malesani (DARK/NBI), P.E. Nissen (Univ. Aarhus), W.J. Schuster
(UNAM), and J.P.U. Fynbo (DARK/NBI), report on behalf of a larger
collaboration:
We observed the afterglow of GRB 080514B (Rapisarda et al., GCN 7715;
Giuliani et al., GCN 7716; de Ugarte Postigo et al., GCN 7719) with the
NOT equipped with ALFOSC. Observations were carried out with the B, R
and I filters.
We clearly detect the afterglow in all bands. On mean time May 16.184 UT
(1.77 days after the trigger), we measure R = 22.52 +- 0.10 (AB),
calibrated against SDSS r magnitudes. The detection in B implies a
redshift limit z < 3.7.
GCN Circular 7745
Subject
GRB 080514B: Further NIR observations
Date
2008-05-18T03:40:55Z (17 years ago)
From
Adria C. Updike at Clemson U <aupdike@clemson.edu>
Adria C. Updike, Ginger Bryngelson, and Dieter H. Hartmann (Clemson
University) report on behalf of the Clemson GRB Follow-Up Team:
We re-imaged the field of GRB 080514B (Hurley et al., GCN 7715) with the
KPNO 4m + NEWFIRM under good weather conditions. We obtained 15 minutes
in the J and H bands approximately 48 hours after the trigger. In stacked
images, we marginally detect the afterglow (Postigo et al., GCN 7719) at J
= 20.7 +/- 0.3 (calibrated to the 2MASS catalog). We do not detect the
afterglow in the H band with a limiting magnitude of 20.2.
This message may be cited.
GCN Circular 7750
Subject
GRB 080514B: second epoch Swift XRT data confirms the X-ray afterglow
Date
2008-05-19T10:23:12Z (17 years ago)
From
Paolo Esposito at INAF-IASF,Milano <paoloesp@iasf-milano.inaf.it>
P. Esposito, A. De Luca, A. Tiengo, G. Vianello (INAF-IASF MI),
K.L. Page (U. Leicester) report:
GRB 080514B was discovered by the SuperAGILE detector on May
14th, at 09:55:56 UT (Rapisarda et al., GCN Circ. 7715) and
possibly detected at energies E>50 MeV in AGILE GRID data
(Giuliani et al., GCN Circ. 7716).
The first Swift/XRT observation was performed on May 14th at
20:12, starting about 37 ks after the GRB trigger (Page et al.,
GCN Circ. 7723). A likely afterglow candidate was found, with a
flux decay described by a power-law (slope: 1.5+/-1.0; GCN Circ.
7723). The spectrum was modelled with an absorbed ( 1.2x10^21 cm^-2)
power-law, with photon index = 2.06 (GCN Circ. 7723).
Swift/XRT observed again the field of GRB 080514B on May 16th at
20:13, about 58 hours after the trigger. 6 ks of data in Photon
Counting mode were collected in three consecutive orbits, spanning
5 hours.
The candidate X-ray afterglow (GCN Circ. 7723) is significantly
detected with a 0.3-10 keV observed flux of (1.9+/-0.8)x10^-13
erg cm^-2 s^-1 (assuming the spectrum of Circ. 7723).
The new XRT data confirm the fading trend reported in (GCN Circ.
7723) and better constrain the decay slope at 1.6 +0.3/-0.2.
We thank the Swift PI, N. Gehrels, for approval of this TOO, and
the the Swift team (in particular the duty scientists and science
planners) for performing it.
GCN Circular 7751
Subject
Konus-Wind observation of GRB 080514B
Date
2008-05-19T13:14:50Z (17 years ago)
From
Valentin Pal'shin at Ioffe Inst <val@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks,
and T. Cline on behalf of the Konus-Wind team report:
The bright GRB 080514B localized by SuperAGILE/IPN (Rapisarda et al.,
GCN 7715) triggered Konus-Wind at T0=35758.672 s UT (09:55:58.672).
The burst light curve shows a multipeaked structure with a duration of
~7 s.
As observed by Konus-Wind the burst
had a fluence of 3.23(-0.26, +0.27)x10^-5 erg/cm2,
and a 16-ms peak flux measured from T0+3.328 s
of (2.07 +/- 0.43)x10^-5 erg/cm2/s
(both in the 20 keV - 5 MeV energy range).
The time-integrated spectrum of the burst
(from T0 to T0+12.032 s) is well fitted (in the 20 keV-5 MeV range)
by GRBM (Band) model for which:
the low-energy photon index is alpha = -0.599(-0.134, +0.161),
the high energy photon index beta = -2.48(-0.25, +0.18),
the peak energy Ep = 224 (-22, +23) keV (chi2 = 72.3/76 dof).
All the quoted errors are at the 90% confidence level.
The Konus-Wind light curve of this GRB is available
at http://www.ioffe.rssi.ru/LEA/GRBs/GRB080514_T35758/
GCN Circular 7752
Subject
GRB 080514B: Suzaku WAM observation of the prompt emission
Date
2008-05-20T06:20:41Z (17 years ago)
From
Yoshitaka Hanabata at Hiroshima U <hanabata@hep01.hepl.hiroshima-u.ac.jp>
Y. Hanabata, T. Uehara, Y. Fukazawa, T. Takahashi, C. Kira (Hiroshima U.),
M. Ohno, M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA),
K. Yamaoka, S. Sugita (Aoyama Gakuin U.),
K. Onda, M. Tashiro, Y. Terada, Y. Urata, A. Endo, N. Kodaka,
K. Morigami, T. Sugasahara, W. Iwakiri (Saitama U.),
Y. E. Nakagawa, T. Tamagawa (RIKEN), T. Enoto, K. Nakazawa,
K. Makishima (Univ. of Tokyo), E. Sonoda, M. Yamauchi, H. Tanaka,
R. Hara (Univ. of Miyazaki), S. Hong (Nihon U.),
on behalf of the Suzaku WAM team, report:
The long GRB 080514B, (SuperAGILE/IPN: Rapisarda et al., GCN7715 )
triggered the Suzaku Wide-band All-sky Monitor (WAM)
which covers an energy range of 50 keV - 5 MeV at 09:55:57 UT (=T0).
The observed light curve shows a multi-peaked structure
starting at T0-1s , ending at T0+7s, with a duration (T90) of about
6.3 seconds. The fluence in 100 - 1000 keV was 1.4(+0.2,-0.1) x 10^-5
erg/cm^2. The 1-s peak flux measured from T0+2s was 11.3(+0.5,-0.1)
photons/cm^2/s in the same energy range.
A preliminary result shows that the time-averaged spectrum from
T0-1s to T0+7s is well fitted by a GRB Band model as follows.
the low-energy photon index alpha: -1.4(+0.6,-0.5),
the upper limit of the high-energy photon index beta: -2.5
and the peak energy Epeak: 259 (+43, -104) keV (chi^2/d.o.f = 27.9/23).
----
All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.
----
The light curves for this burst are available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html
GCN Circular 7759
Subject
GRB 080514B: UVOT Observations
Date
2008-05-21T14:07:20Z (17 years ago)
From
Stephen Holland at USRA/NASA/GSFC/SSC <sholland@milkyway.gsfc.nasa.gov>
S. T. Holland (CRESST/USRA/GSFC) reports on behalf of the Swift/UVOT
team:
The Swift/UVOT observed the field of GRB 080514B starting 37,005 s
after the SuperAGILE/IPN detection (Rapisarda et al., GCN Circ. 7715).
We detect the optical afterglow in the b, u, uvw1, and uvm2 filters at
the location of the IAC80 optical afterglow (de Ugarte Postigo, et al.,
2008, GCNC 7719). The UVOT source position is
RA(J2000.0) = 21:31:22.71
Dec(J2000.0) = +00:42:28.4
with an estimated uncertainty of +/-0.60 arcsec (radius, 90%
confidence).
Magnitudes and upper limits are reported below.
Filter T_start (s) T_stop Exposure Mag Err Comment
v 38,184 43,906 352 >20.1 3-sigma UL
b 37,449 48,630 559 20.92 0.27
u 37,229 48,415 559 19.97 0.17
uvw1 37,005 48,198 1118 20.74 0.24
uvm2 38,333 44,537 1030 20.83 0.32
uvw2 37,601 49,441 2199 >22.1 3-sigma UL
white 209,879 228,394 5360 >23.3 3-sigma UL
The above magnitudes and upper limits are not corrected for the
Galactic extinction along the line of sight corresponding to a
reddening of E_{B-V} = 0 .06 mag (Schlegel et al., 1998, ApJS,
500, 525). The photometry is on the UVOT flight system described
in Poole et al. (2008, MNRAS, 383,627). The non-detections in
the uvw2 filters may indicate that the redshift is z >~ 1.9.
GCN Circular 7760
Subject
GRB 080514B: pseudo-z= 1.8 from prompt emission spectrum
Date
2008-05-21T15:09:41Z (17 years ago)
From
Alexandre Pelangeon at LATT,OMP,Toulouse <alexandre.pelangeon@ast.obs-mip.fr>
A. Pelangeon & J-L. Atteia (LATT-OMP) report:
We used the spectral parameters of GRB 080514B
provided by Golenetskii et al. (GCNC 7751) to compute
the spectral pseudo-redshift(**) of this burst localized
by SuperAGILE/IPN (Rapisarda et al., GCN 7715).
We find a pseudo-redshift pz= 1.76 � 0.30
We note that this redshift estimate is consistent with
the observations of the afterglow in B band performed
with the NOT, that may imply a redshift z < 3.7
(Malesani et al., GCNC 7734). This is also consistent
with the observations of the Swift/UVOT (Holland et al.,
GCNC 7759), in which the non-detection of the afterglow
in uvw2 filters may suggest z >~ 1.9
(**) cf. http://www.ast.obs-mip.fr/grb/pz
GCN Circular 7874
Subject
GRB 080514B: Spectroscopic constraints and probable host galaxy
Date
2008-06-13T16:18:12Z (17 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, J. S. Bloom (UC Berkeley), H.-W. Chen (U Chicago), R. J.
Foley, A. A. Miller, J. Shiode, J. Brewer, D. Starr, and R. Kennedy
(UCB) report:
On the night of 2008-06-07 (UT) we observed the location of the
Super-AGILE burst GRB 080514B (GCN 7715, Rapisarda et al.) with Keck I /
LRIS in g and R filters for 1080s and 960s respectively, starting at
12:53 UT. We detect a source consistent with the afterglow position (de
Ugarte Postigo et al., GCN 7719) in both filters. Photometry within a
1.1" radius aperture gives an magnitude (calibrated to three nearby USNO
B1.0 stars) of:
R = 23.9 +/- 0.2 (t = 24.1 days)
Compared to the measurement of Malesani et al. (R = 22.52 at 1.77 days,
GCN 7734), this would suggest a decay index of only about alpha = 0.5
were this the GRB afterglow, which is unlikely at such late times. More
likely, the source represents a relatively bright host galaxy of this burst.
However, analysis of a 2x1200s Gemini-North spectrum using GMOS taken at
the afterglow location (offset <0.5" from the host from a comparison
from the Gemini i-band acquisition image) 1.9 days after the GRB shows
no significant emission or absorption features over the usable spectral
range from 4000-6720 Angstroms. The continuum flux extends all the way
to 4000 Angstroms without evidence of Lyman-alpha forest absorption,
which imposes a redshift constraint of z < 2.3. Further follow-up is
encouraged.
A colorized image of the field is available at:
http://lyra.berkeley.edu/~dperley/080514b/080514b_color.png