GRB 060814

Christina C. Thoene (DARK/UC Berkeley), Daniel A. Perley and J. S. Bloom
(UC Berkeley) report:

On 2007 April 15 (UT) we imaged the field of GRB 060814 with Keck I 10m
telescope + LRIS for 750s in I and 840s in V under poor seeing conditions.
The host galaxy reported by Malesani et al. (GCN 5456
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 ) and others is
well-detected at a position consistent with the locations of the IR (Levan
et al., GCN 5455
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 ) and X-ray (GCN 5451
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 ; [1]) transients. A finding chart of
the field can be found at:

http://lyra.berkeley.edu/~dperley/060814/060814_lris_v.png

We also took spectra of the host galaxy on July 18 with LRIS, using grism
600/4000 and dicroic 560, which covers the wavelength range between 5500
and 9700 AA in the red arm. From the detected [OII] 3729 AA and [OIII]
5008 AA emission lines, we infer a redshift of z=0.84 for the host galaxy.
The second [OIII] line at 4959 is marginally detected whereas H beta lies
in the atmospheric absorption lines and could not be detected.
An image of the 2D spectrum indicating the detected emission lines can be
found at:

http://lyra.berkeley.edu/~cthoene/GRBs/GRB060814_2dspec.jpg


footnote:

[1] 14:45:21.29, +20:35:10.7, 90% unc. 0.9", from
http://astro.berkeley.edu/~nat/swift/xrt_pos.html (v0.0)

M. Suzuki, Y. Terada, T. Tamagawa (RIKEN), M. Ohno, T. Takahashi,
 T. Asano, T. Uehara, Y. Fukazawa (Hiroshima U.), K. Yamaoka,
 S. Sugita (Aoyama Gakuin U.), K. Abe, K. Onda, M. Suzuki,Y. Urata, 
 M. Tashiro (Saitama U.), S. Hong (Nihon U.), K. Nakazawa,
 T. Takahashi (ISAS/JAXA), T. Enoto, R. Miyawaki, K. Kokubun
 K. Makishima (Univ. of Tokyo),  
 on behalf of the Suzaku WAM team report:

 The bright, long burst, GRB 060814 (Swift-BAT trigger #224552;
 A. Moretti et al., GCN 5447
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 ; GCN 5451
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 ; M. Stamatikos et al., GCN 5459
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 ),
 triggered the Suzaku Wideband All-sky Monitor (WAM) which covers an
 energy range of 50 keV - 5 MeV at 23:02:17.783 (UT).
 The 1st, 2nd and 3rd peaks (GCN 5459
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 ) are clearly seen in the light
 curve observed by WAM and the 4th peak is marginally seen.
 The T90 duration is ~125 seconds.
 The fluence in 100 - 1000 keV was 2.2 (-0.3 +0.2)X10^-5 erg/cm2.
 The 1-s peak flux was 2.9 (-1.2 +0.1) photons/cm2/s
 in the same energy range.

 Preliminary result shows that the time-averaged spectrum
 is well-fitted by a power law with an exponential
 cutoff (A * E^{-alpha} * exp(-(2-alpha)*E/Epeak)) 
 having the following parameters:
 alpha        1.6 (-0.5, +0.4), and
 Epeak        312 (-152, +159) keV.

 All the quoted errors are at statistical 90% confidence level, 
 in which systematic errors are not included.

A. Pelangeon & J-L. Atteia (LATT-OMP) report:

We have used the spectral parameters obtained for the most intense part
of GRB 060814 -- from T0 to T0+8.448 s, Konus time
(V. Pal'shin, Ioffe Inst., private communication) --
observed by Konus-Wind (Golenetskii et al., GCNC 5460)
to compute the spectral pseudo-redshift** of this bright burst
detected by SWIFT-BAT (Moretti et al., GCNC 5447).

We find a pseudo-redshift pz= 2.4 +/- 0.8

We thank V. Pal'shin for having kindly performed the spectrum analysis  of
the most intense part and providing us the spectral parameters.


** cf. http://www.ast.obs-mip.fr/grb/pz

A. Moretti (INAF-OAB), C. Guidorzi (Univ. Bicocca & INAF-OAB),
P. Romano (INAF-OAB), D.N. Burrows (PSU), N. Gehrels (GSFC)
report on behalf of the Swift-XRT team:

Based on the most recent downlinked data on GRB060814 (trigger number
224552) we find clear evidence of a break in the light curve at
42(+/-6) ks from the burst trigger (see the light curve at
http://www.brera.inaf.it/~moretti/grbplot/xrt060814.gif )
which could be a jet break.
The light curve slope steepens from 1.04+/-0.05 to 1.9+/-0.3
(errors are quoted at 90% confidence level).
In order to convert the XRT count rate to absorbed (unabsorbed)
flux the conversion factor is 4.9E-11 (8.5E-11)

Therefore we encourage optical data collection on this GRB in order to
measure the redshift and to test whether this break is achromatic.

This circular is an official product of the Swift-XRT team.

A.J. Levan (U. Hertfordshire), E. Rol, N.R. Tanvir (U. Leicester),
A. Fruchter (STScI), J. Rhoads (ASU), C. Davis, A. Adamson (JAC)
report for a larger collaboration:

We obtained a second epoch of K-band observations of GRB 060814
at UKIRT beginining at August 16, 06:46 UT. The suggested IR
afterglow (GCN Circ 5455
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 ) is still detected and has faded by
0.4 +/- 0.1 mags, confirming its association with GRB 060814.

The afterglow decay is very slow, with alpha~0.25. This may
well represent a signficant contribution from an underlying
host galaxy (see GCN Circs 5456
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  & 5457).

S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and
T. Cline on behalf of the Konus-Wind team report:

The long GRB 060814 (Swift-BAT trigger #224552; Moretti et al., GCN 5447
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 )
triggered Konus-Wind at T0=82954.447 s UT (23:02:34.447).

As observed by Konus-Wind the burst shows
two main pulses and a weak extended emission seen up to T-T0 ~200s.
The most intense pulse starts at T-T0 ~ -21 s
and has a duration of ~40 s,
the second pulse starts at T-T0 ~38 s and has a duration of ~35 s.
T90 (18-1160 keV) is 134 +- 4 sec.

The burst fluence is 2.69(-0.79, +0.12)x10^-5 erg/cm2,
and the 256-ms peak flux measured from T0+0.576 s
2.13(-0.55, +0.29)x10^-6  erg/cm2/s
(both in the 20 keV - 1 MeV energy range).

The spectrum of the burst integrated from T0 to T0+73.984 s
is well fitted (in the 20 keV - 1 MeV range)
by a power law with exponential cutoff model:
dN/dE ~ E^(-alpha) * exp(-(2-alpha)*E/Ep)
with alpha = 1.43(-0.16, +0.15)
and Ep = 257(-58, +122) keV (chi2 = 65/57 dof).

All the quoted errors are at the 90% confidence level.

M. Stamatikos (GSFC/ORAU), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/ORAU), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), M. Koss (GSFC/UMD),
C. Markwardt (GSFC/UMD), A. Moretti (INAF-OAB), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS),
J. Tueller (GSFC)
on behalf of 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 060814 (trigger #224552)
(Moretti, et al., GCN Circ. 5447
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 ).  The BAT ground-calculated position is
RA,Dec = 221.336, 20.593 deg {14h 45m 20.6s, 20d 35' 36.3"} (J2000)
+- 0.7 arcmin, (radius, sys+stat, 90% containment).  The partial coding was 64%.
 
There are four main peaks.  The first starts at ~T-10 sec and blends into
the second peak which peaks at T+16 and ends around T+40 sec. The second peak
is the brightest.  The third peak starts roughly T+50, peaks at ~T+70 and
ends at ~T+110 sec.  It is half as bright as the second peak.  The fourth and
much smaller peak is about 40 sec wide and peaks at T+130 sec.
T90 (15-350 keV) is 146 +- 10 sec (estimated error including systematics).
 
The time-averaged spectrum from T-9.4 to T+224 is best fit by a simple power-law
model.  The power law index of the time-averaged spectrum is 1.56 +- 0.03.
The fluence in the 15-150 keV band is 1.50 +- 0.02 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+15.40 sec in the 15-150 keV
band is 7.4 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90%
confidence level.

E. O. Ofek and S. B. Cenko (Caltech) report on behalf of a larger
collaboration:

We have imaged the field of GRB 060814 (Moretti et al; GCN 5447
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 ) with the
automated Palomar 60-inch telescope.
We obtained 19 x 180 s i-band images and 15 x 180 s z-band images,
both at UTC 2006 August 15.24 (mid time; 0.28 d after the burst).
We identify the extended source reported by Malesani (GCN 5456
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 ),
on the edge of the revised XRT error circle (GCN 5451
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 ).
We note that this source is also detected in the SDSS
g-band image, and possibly also in the SDSS i-band image.
The magnitude of this source is g=22.9 and i=22.5, as measured
in the SDSS g-band and P60 i-band images, respectively.

We cannot identify any other sources within the XRT error circle
to a limiting magnitude of about 23.0 and 21.5 in i- and z-band, respectively.


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 This Mail Was Scanned By Mail-seCure System
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S. B. Cenko, E. O. Ofek (Caltech), D. Gelino (Michelson Science Center,
Caltech), Tommy Thompson (UC-San Diego), P. A. Price (IfA), and E. Berger
(Carnegie) report on behalf of a larger collaboration:

We have imaged the field of GRB 060814 (Moretti et al.; GCN 5447
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 ) with the
Wide Field Infrared Camera mounted on the Palomar 200" Hale Telescope.
Images were taken in the Ks band at a mean epoch of approximately 03:25 15
August UT (~ 4.4 hours after the burst).

Near the revised XRT error circle (Moretti et al.; GCN 5451
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 ), we find
only the possible counterpart identified by Levan et al. (GCN 5455
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 ) and
Malesani (GCN 5456
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 ).  We measure the magnitude of this extended object to
be Ks ~ 18.2 (calculated with respect to several nearby 2MASS objects).
This is in agreement with the measurement of Levan et al. several hours
later, indicating significant host contribution to any possible afterglow.

The limiting magnitude of our co-added stack is approximately Ks > 18.5.

D. Malesani (SISSA) reports on behalf of the MISTICI collaboration:

Following the revised position for the X-ray afterglow of GRB 060814 
(Moretti et al., GCN 5447
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 , 5451
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 ), I have looked at the VLT images taken 
the last night (Malesani et al., GCN 5450
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 ).

On the edge of the XRT error box, there is a source. It is extended, or 
it may be the superposition of more than one source (the seeing was 
0.8"). The source is detected in both R and I images, and is not visible 
in the SDSS frames (Cool et al., GCN 5449
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 ). However, it is likely 
fainter than the SDSS limit. The "centroid" of the object has the 
following approximate coordinates:

alpha = 14:45:21.3
delta = +20:35:10.19

A finding chart is posted at the following URL:

http://www.sissa.it/~malesani/GRB/060814/GRB060814_finder.jpg

At the moment, it is not clear whether the object is related to the GRB.

This message can be cited.

A.J. Levan (U. Hertfordshire), N.R. Tanvir, E.Rol (U. Leicester), A.
Fruchter (STScI), A. Adamson (JAC) report on behalf of a larger
collaboration:

We observed the location of GRB 060814 with UKIRT beginning at 05:50 UT
(approximately 7 hours post burst). Observations were obtained in the
K-band. Within the refined XRT error circle (Moretti GCN Circ. 5451
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 ) we 
find a single source at

RA: 14:45:21.1 (J2000)
DEC: +20:35:09 (J2000)

With a magnitude of K~18. We suggest this may be the IR afterglow of GRB
060814.

Further observations are planned.

A. Cucchiara and A. Moretti report on behalf of the
Swift/UVOT team:

The Swift UVOT began observing GRB 060814 (trigger #224552,
A. Moretti et al., GCN Circ. 5447
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 ) 80 seconds after the BAT
trigger. No optical afterglow is detected in the XRT refined error
circle (A. Moretti et al, GCN Circ. 5451
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 ).

The 3-sigma limiting magnitudes for the finding chart and the
coadded images for the UVOT filters are listed below:

Finding chart:

Filter        T_range (s)    Exposure (s)    3sigma UL
White         80-178         98              19.70

Coadded images:

Filter        T_range (s)    Exposure (s)    3sigma UL
WHITE         80-20180       1445            21.39
V             180-12176      2008            20.36
B             388-25364      2085            21.53
U             364-24651      2310            21.04
W1            340-23738      2138            20.52
M2            285-13073      1080            20.50
W2            416-7882       349             20.02

T_range is calculated from the time of the burst. No correction has
been made for the Galactic reddening of E(B-V) = 0.04 mag
(Schlegel et al. 1998) along the line of sight to the burst.

A. Moretti (INAF-OAB), C. Guidorzi (Univ. Bicocca & INAF-OAB),
P. Romano (INAF-OAB) report on behalf of the Swift-XRT team:

We have analysed the first 4 orbits of Swift-XRT data obtained for GRB
060814 (trigger number 224552). The data consist of 428 s in Windowed
Timing (WT) mode, starting 72 seconds after the BAT trigger and 9.2 ks
in Photon Counting (PC) mode. Using PC data we obtain a refined
position of:

RA(J2000) =   14 45 21.48
Dec(J2000) = +20 35 11.8

with an estimated uncertainty radius of 3.5 arcsec (90% containment).

The light-curve, initially, shows a steep decay (alpha1=2.3+/-0.1) up to a
break at t_break1=1292+/-140.s. On top of this steep decay there is a
flare peaking at 150 s. After the break, the afterglow shows a
shallow decay (alpha2=0.3+/-0.1) up to t_break2=7500+/-2000 s, when
the light-curve steepens (alpha3=1.0+/-0.2).

The spectrum formed from all the WT data (< t_break1) can be modelled
with a power-law of photon index Gamma = 1.67 +/- 0.03, with an excess
absorbing column of NH = (2.7 +/- 0.2)e21 cm^-2 in addition to the
Galactic value of 2.40e20 cm^-2. The spectrum formed from the PC data
(> t_break1) is significantly softer than the pre-break spectrum: it
can be modelled with a power-law of photon index Gamma = 2.2 +/- 0.10,
with an absorbing column of NH = (3.6 +/- 0.4)e21 cm^-2, which is
marginally consistent with the previous one.

Assuming the light-curve continues to decay with alpha3=1.0, the
count rate at 24 hours is predicted to be 0.030 count s^-1. This
corresponds to an observed (unabsorbed) flux of 1.5e-12 (2.7e-12)
erg cm^-2 s^-1.

This circular is an official product of the Swift-XRT team.


[GCN OPS NOTE(15aug06): This Circular was delayed by ~4 hrs due to problems
at the GCN end.]

D. Malesani (SISSA) and R. Scarpa (ESO) report on behalf of the MISTICI 
collaboration:

We have observed the field of GRB 060814 (Moretti et al., GCN 5447
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 ). 
Observations were carried out with the ESO VLT UT2 equipped with FORS1, 
under thin clouds.

We find no source at the position of the X-ray afterglow, with a 3sigma 
limiting magnitude R = 24. The mean time was Aug 15.0 UT (58 minutes 
after the burst).

This message can be cited.

[GCN OPS NOTE(16aug06): Per author's request, 'F. Patat' was replaced
with 'R. Scarpa'.]

Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona), David W. Hogg
(NYU), Michael R. Blanton (NYU), David J. Schlegel (LBNL), J.  
Brinkmann (APO),
Donald Q. Lamb (Chicago), Donald P. Schneider (PSU), and Daniel E.  
Vanden Berk
(PSU) report:

The Sloan Digital Sky Survey (SDSS) imaged the field of burst GRB060814
prior to the burst.  As these data should be useful as a pre-burst  
comparison
and for calibrating photometry, we are supplying the images and  
photometry
measurements for this GRB field to the community.

Data from the SDSS, including 5 FITS images, 3 JPGS, and
3 files of photometry and astrometry, are being placed at
http://mizar.as.arizona.edu/~grb/public/GRB060814

We supply FITS images in each of the 5 SDSS bands of a 8'x8' region  
centered
on the GRB position (ra=221.348 (14:45:23.5), dec=20.5830 (20:34:58.8);
Swift-BAT TRIGGER 224552), as well as 3 gri color-composite JPGs (with
different stretches). The units in the FITS images are nanomaggies  
per pixel.
A pixel is 0.396 arcsec on a side. A nanomaggie is a flux-density  
unit equal
to 10^-9 of a magnitude 0 source or, to the extent that SDSS is an AB  
system,
3.631e-6 Jy.  The FITS images have WCS astrometric information.

In the file GRB060814_sdss.calstar.dat, we report photometry and  
astrometry
of 347 bright stars (r<20.5) within 15' of the burst location.  The  
magnitudes
presented in this file are asinh magnitudes as are standard in the  
SDSS (Lupton
1999, AJ, 118, 1406). Beware that some of these stars are not well- 
detected
in the u-band; use the errors and object flags to monitor data quality.

In the files GRB060814_sdss.objects_flux.dat and
GRB060814_sdss.objects_magnitudes.dat, we report photometry of 1071
objects detected within 6' of the GRB position.  We have removed  
saturated
objects and objects with model magnitudes fainter than 23.0 in the r- 
band.
The fluxes listed in GRB060814_sdss.objects_flux.dat are in nanomaggies
while the magnitudes listed in GRB060814_sdss.objects_magnitudes.dat are
asinh magnitudes.

All quantities reported are standard SDSS photometry, meaning that  
they are
very close to AB zeropoints and magnitudes are quoted in asinh  
magnitudes.
Photometric zeropoints are known to about 2% rms.  None of the  
photometry
is corrected for dust extinction.  The Schlegel, Finkbeiner, and Davis
(1998) predictions for this region are A_U=0.201 mag, A_g=0.148 mag,  
A_r =
0.107 mag, A_i=0.081 mag, and A_z=0.058 mag.

There are currently no objects within 6 arcminutes of the GRB  
position in
the SDSS spectroscopic database.

SDSS astrometry is generally better than 0.1 arcsecond per coordinate.
Users requiring high precision astrometry should take note that the SDSS
astrometric system can differ from other systems such as those used  
in other
notices; we have not checked the offsets in this region.

More detailed information pertaining to our SDSS GRB releases can be  
found
in our initial data release paper (Cool et al. 2006, astro-ph/0601218).
See the SDSS DR4 documentation for more details: http://www.sdss.org/ 
dr5.

These data have been reduced using a slightly different pipeline than  
that
used for SDSS public data releases.  We cannot guarantee that the  
values here
will exactly match those in the data release in which these data are  
included.
In particular, we expect the photometric calibrations to differ by of  
order
0.01 mag.

This note may be cited, but please also cite the SDSS data release  
paper,
Adelman-McCarthy et al. (2006, ApJS, in press, astro-ph/0507711),  
when using
the data or referring to the technical documentation.

Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:

We imaged the field of GRB 060814 detected by SWIFT
(trigger 224552) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

First image was acquired 21.5s after the GRB trigger
(6s after the notice). 3 first images were recorded
during the gamma propt emission.

The field elevation decreased from 11 degrees
above horizon and weather conditions were good.

Date of trigger : t0 = 2006-08-14T23:02:18.816

First image is 60s exposure trailed. No OT is visible:
t0+21.5s to t0+81.5s : R > 14.8

Second image is 30s exposure. No OT is visible:
t0+88s to t0+118s : R > 15.7

Third image is 30s exposure. No OT is visible:
t0+125s to t0+155s : R > 15.7

Fourth image is 30s exposure. No OT is visible:
t0+161s to t0+191s : R > 15.7

We co-added a series of exposures. No OT is visible:
t0+88s to t0+228s : R > 17.4

Magnitudes were estimated with the nearby USNO-B1 stars

Galactic coordinates are lon= 24.9891 lat=+63.2011
and the galactic extinction in R band is 0.1 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.

A. Moretti (INAF-OAB), S. D. Barthelmy (GSFC),
J. R. Cummings (NASA/UMD), C. Guidorzi (Univ Bicocca&INAF-OAB),
K. M. McLean (LANL/UTD), D. M. Palmer (LANL), P. Romano (INAF-OAB),
M. Stamatikos (NASA/ORAU) and D. E. Vanden Berk (PSU) report on
behalf of the Swift Team:

At 23:02:19 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 060814 (trigger=224552).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA,Dec 221.348, +20.583 {14h 45m 23s, +20d 34' 58"} (J2000)
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows at least 3 large peaks. 
The first peak starts at T-10 sec, peaks at T+16 sec with 12,000 cnts/sec. 
The second peaks at T+70 sec at 6000 cnts/sec.  The third peaks at T+120 sec
at ~1000 cnts/sec. 

The XRT began observing the field at 23:03:30 UT, 72 seconds after the
BAT trigger. XRT found a bright variable X-ray source
located at RA(J2000) = 14h 45m 21.2s, Dec(J2000) = +20d 35' 02.7", with an
estimated uncertainty of 5.0 arcseconds (90% confidence radius). 
This location is 32 arcseconds from the BAT on-board position, within
the BAT error circle. The initial flux in the 0.1s image was
5.7e-08 erg/cm2/s (0.2-10 keV). 

UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 80 seconds after the BAT trigger. No
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 typical
3-sigma upper limit has been about 18.5 mag. The 8'x8' region for the
list of sources generated on-board covers 100% of the XRT error
circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to
E(B-V) of  0.04.