GRB 080319C

W. Li, R. Chornock, and A. V. Filippenko, University of California 
at Berkeley, on behalf of the KAIT GRB team, report:

KAIT responded to GRB 080319C (Swift trigger 306778) and was taking 
images. There is an afterglow candidate at position

RA  = 17:15:55.54
DEC = +55:23:30.8
(equinox J2000)

The measured magnitude is R = 17.4 at 12:27:55 UT. Further observations
are ongoing.

C. Pagani (PSU), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), P. A. Evans (U Leicester),
N. Gehrels (NASA/GSFC), O. Godet (U Leicester),
S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU),
V. Mangano (INAF-IASFPA), J. P. Osborne (U Leicester),
K. L. Page (U Leicester), A. M. Parsons (GSFC), J. L. Racusin (PSU),
B. Sbarufatti (INAF-IASFPA), M. Stamatikos (NASA/ORAU),
R. L. C. Starling (U Leicester), G. Stratta (ASDC) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:

At 12:25:56 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080319C (trigger=306778).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 258.973, +55.410 which is 
   RA(J2000)  =  17h 15m 54s
   Dec(J2000) = +55d 24' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows several overlapping FRED-like
peaks starting at T+0 and ending around T+20 sec.  The peak count rate
was ~8000 counts/sec (15-350 keV), at ~T+0 sec after the trigger. 

The XRT began observing the field at 12:29:40 UT, 224 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 258.9828, 55.3920
which is equivalent to:
   RA(J2000)  = 17h 15m 55.86s
   Dec(J2000) = +55d 23' 31.2"
with an uncertainty of 4.5 arcseconds (radius, 90% containment). This
location is 3 arcseconds from the optical afterglow candidate position. 

UVOT took a finding chart exposure of 100 seconds with the White   
(160-650 nm) filter starting 227 seconds after the BAT trigger. There
is a candidate afterglow in the rapidly available 2.7'x2.7' 
sub-image at   

  RA(J2000)  =	17:15:55.51 = 258.9813   
  DEC(J2000) = +55:23:30.8  = +55.3919    

with a 1-sigma error radius of  about 0.5 arc sec. This position
is 67.4 arc sec. from the center of  the BAT error circle.  This
is consistent with the KAIT position (Li  et al., 2008, GCNC 7441). 
The estimated magnitude is white = 18.8 with a  1-sigma  error of
about 0.5 mag. No correction has been  made for the  expected
extinction corresponding to E(B-V) of 0.03. 

Burst Advocate for this burst is C. Pagani (pagani AT astro.psu.edu). 
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.)

G. G. Williams (MMTO) and P. A. Milne (Steward Observatory), on behalf
of the Super-LOTIS Collaboration, report:

The robotic 0.6-m Super-LOTIS telescope began observing the error box
of GRB 080319C (Swift Trigger 306778, Pagani et al. GCN 7442
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 ) at
12:26:38.5 UT, 42.5 seconds after the trigger.  Our initial
observations include 5 x 10s exposures, 5 x 20s exposures, and 30 x
60s exposures, all in the R-band.

We detect the afterglow reported by Li et al. (GCN 7441
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 ) in our
earliest 10 second exposure.  Using the USNO-B1.0 star (453-025776) at
RA=17:15:51.7, Dec=55:23:38.4 with R2MAG=14.61, we estimate the
following R-band magnitude for the OT:

t_start (UT)	exp t (s)	t_start-t_0 (s)	R Mag
----------------------------------------------------------------
12:26:38.5	10 		42.5 		R = 16.83 +/- 0.13

Additional observations and analysis are ongoing.

MASTER-Net Team:

V. Lipunov, V.Kornilov, D.Kuvshinov, E.Gorbovskoy, N.Tyurina, 
A.Belinski,  A.Krylov, N.Shatskiy, A.Sankovich, V.Vladimirov,
  P.Gritsyk, V.Vibornov, A.Kuznetsov, P.Balanutsa
Sternberg Astronomical Institute, Moscow Union 'Optic'

A. Tlatov, I.Golubov
Kislovodsk Solar Station of the Pulkovo observatory

K.Ivanov
Irkutsk State University

I.Zalognikh
Ural State University, Kourovka

MASTER Very Wide Field Camera located at Kislovodsk Solar Station
(http://observ.pereplet.ru, D=70 mm, 420 square degrees, 11 Mpixel's CCD) 
has moved to the Swift-BAT trigger 306793 and it has taken a series of 5s
exposures starting 92 s after notice arrivel time  708 s after GRB time at 
17 16  57 UT under good weather  condition and moon.


There is no OT was found inside Swift error box brighter than 11.5m.

MASTER-Net team  congratulate "Pi of the Sky" - Team 
with wonderfull and long-awaited  result (Cwiok et al. GCN 7445
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 )!

This message can be cited.
Mailto: lipunov@sai.msu.ru

M. Marisaldi (INAF/IASF Bologna), F. Fornari (INAF/IASF Milano), C. 
Labanti, F. Fuschino, M. Galli, A. Bulgarelli, F. Gianotti, M. Trifoglio, 
G. Di Cocco (INAF/IASF Bologna), E. Costa, E. Del Monte, I. Donnarumma, Y. 
Evangelista, M. Feroci, I. Lapshov, F. Lazzarotto, L. Pacciani, M. 
Rapisarda, P. Soffitta (INAF/IASF Roma), A. Giuliani, S. Vercellone, A. 
Chen, S. Mereghetti, A. Pellizzoni, F. Perotti, M. Fiorini, P. Caraveo 
(INAF/IASF Milano), M. Tavani, G. Pucella, F. D'Ammando, V. Vittorini, A. 
Argan, A. Trois (INAF/IASF Rome), G. Barbiellini, F. Longo, E. Vallazza 
(INFN Trieste), P. Picozza, A. Morselli (INFN Roma-2), M. Prest 
(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:

"The Swift localized GRB 080319C (Pagani et al., GCN 7442
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 ) triggered the 
Mini-Calorimeter (MCAL) instrument onboard the AGILE satellite at 12:25:56 
UT (=T0). The MCAL instrument covers the energy range 350 keV - 10 MeV, 
without imaging capabilities.

The MCAL light curve shows two main overlapping broad peaks, the first 
peaking at T0 and the second peaking at T0+9s in the 350-700 keV energy 
band. Above 700 keV only the first peak is still detected, with 5 sigma 
detection also in the 1.4-2.8 MeV energy band. Using the preliminary 
in-flight calibration, we can estimate the 1-s peak flux in the 350-700 
keV energy band at T0 to be 2.0(-0.8,+0.9) photons/cm2/s.

The Swift localization is out of the field of view of the AGILE Gamma-Ray 
Imaging Detector (GRID), sensitive in the 50 MeV - 50 GeV energy range. 
Analysis of the GRID count rate does not show any detection. The event was 
well outside of the SuperAGILE field of view as well, but the event passed 
through the collimator shield and was weakly detected in the count rate."

We incidentally note that the brighter GRB 080319B (Racusin et al. GCN 
7427
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 ) was not observed by the AGILE instruments due to Earth occultation.

This message may be cited.

C. Pagani, J. L. Racusin, J.A. Kennea, D. N. Burrows (PSU) and P. A. Evans (U
Leicester) report on behalf of the Swift-XRT team:

The Swift-XRT started observing GRB 080319C (trigger=306778, Pagani et al. GCN
7442
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 ) at 12:29:40 UT, 224 seconds after the BAT trigger. The Swift slew to the
burst was delayed because of an Earth constraint. The current dataset consist
of 2.2ks of Photon Counting mode data from the first orbit of observation.

Using 595 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 = 258.97980,
55.39197 which is equivalent to:

RA (J2000):  17 15 55.15
Dec (J2000): +55 23 31.1

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

The 0.3-10 keV X-ray light curve starts at a count rate of ~7 counts/s and peaks
at ~18 counts/s at T+360 seconds, after which it shows a decline with a decay
slope of 0.9 +/- 0.1 with hints of superimposed flaring activity.

The spectrum of the PC data can be well fit by an absorbed powerlaw with photon
index 1.73 +/- 0.06 and column density of (1.5 +/- 0.1)e21 cm^-2, in excess of
the Galactic column density of 2.21e20 cm^-2 in this direction. The average
observed 0.3-10 keV flux is 1.0e-10 erg cm^-2 s^-1, which corresponds to an
unabsorbed flux of 1.3e-10 erg cm^-2 s^-1. The counts to observed flux
conversion factor at the time of this spectrum is 4.3e-11 erg cm^-2 count^-1.

If the underlying powerlaw decay continues as is, we predict an XRT count rate
of 0.11 counts/s at T+24hr, which corresponds to an observed 0.3-10keV flux of
4.7e-12 erg cm^-2 s^-1.

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

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
GRB080319C 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/GRB080319C

We supply FITS images in each of the 5 SDSS bands of a 8'x8'
region centered on the GRB position (ra=258.983 (17:15:55.9),
dec=55.3920 (55:23:31.2); GCN 7442
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 ), 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 GRB080319C_sdss.calstar.dat, we report photometry
and astrometry of 467 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 GRB080319C_sdss.objects_flux.dat and
GRB080319C_sdss.objects_magnitudes.dat, we report photometry
of 508 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 GRB080319C_sdss.objects_flux.dat are in nanomaggies while
the magnitudes listed in GRB080319C_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=0.134 mag, A_g=0.098 mag,
A_r = 0.071 mag, A_i=0.054 mag, and A_z=0.038 mag.

The file GRB080319C_sdss.spectro.dat contains a list of the
4 objects with SDSS spectroscopy within 6 arcminutes of the
GRB position.  In addition to the redshift and 1-sigma error
for each object, this file also lists the object spectroscopic
classification.


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, PASP 118, 733).  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. (2007, ApJS, 172, 634),
when using the data or referring to the technical documentation.

W. Li and A. V. Filippenko, University of California, Berkeley,
report on behalf of the KAIT GRB team:

We have analyzed the KAIT observations of the optical afterglow (OA) of GRB
080319C (GCN 7442
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 , GCN 7460
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 ) as reported in GCN 7441
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 . Our first 5 s unfiltered
observation started at 12:27:11 UT, 75 s after the BAT trigger. Four subsequent
5 s exposures from t = 81 s to 100 s indicate a smoothly decaying behavior (but
perhaps not power law). After reaching a minimum at t = 180 s (or perhaps a bit
earlier), the OA brightened steeply to a second prominent peak centered at t ~
320 s, after which the OA decayed as an approximate power law, with evidence
for a gradually steepening decay index. Selected photometry, all unfiltered but
calibrated to the R band via USNO B1:

  t_start (s) exp (s)    mag  mag_err

          75    5.0      17.353 0.057 
         100    5.0      17.71  0.062 
         180   20.0      17.95  0.051
         271   20.0      17.322 0.022
         362   20.0      17.32  0.023 
         453   20.0      17.487 0.027
         845   20.0      18.06  0.048 
        1429   20.0      18.866 0.096

J. Wren, W.T. Vestrand, P.R. Wozniak, H. Davis
of Los Alamos National Laboratory report:

Our RAPTOR telescopes responded to Swift trigger 306778
(Pagani et al., GCN 7442
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 ) at 12:26:30.66 UTC, 33.70 seconds
after the trigger.  We detect the optical counterpart
initially reported by Li (GCN 7441
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 ).  Our measurements are
consistent with those reported by KAIT (GCN 7441
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  and 7475
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 )
and Super-LOTIS (7443).  Our images became dominated by the
morning twilight at about 12:35 UTC.  The unfiltered
measurements reported in the following table are calibrated
to the USNO-B1 R band.

t-mid(s)    exp(s)     mag     mag-err
-----------------------------------------
47.60       5.0       16.97     0.32
85.27       80.3      17.65     0.18
177.36      61.5      18.22     0.36
228.87      61.1      17.32     0.16
293.28      61.7      17.41     0.20
358.12      62.1      17.13     0.16

M. Stamatikos (GSFC/ORAU), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), C. Pagani (PSU),
D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC),
G. Sato (GSFC/ISAS), J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-120 to T+88 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 080319C (trigger #306778)
(Pagani, et al., GCN Circ. 7442
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 ).  The BAT ground-calculated position is
RA, Dec = 259.006, 55.393 deg which is 
   RA(J2000)  =  17h 16m 01.4s 
   Dec(J2000) = +55d 23' 33.0" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 30%.
 
For the limited event-by-event data we have received on this burst,
the mask-weighted light curve shows 2 (possibly 3) overlapping
FRED-like peaks starting at T-0.5 sec, peaking at T+0.2 sec, and
ending at ~T+50 sec.  The event-by-event data for this m-w lightcurve
ends at T+88 sec.  The on-board raw countrate lightcurve shows
no activity after the T+88 sec limit of the event data, but the sensitivity
is significantly less for this data product.  T90 (15-350 keV) is 34 +- 9 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-0.3 to T+51.2 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.37 +- 0.07.  The fluence in the 15-150 keV band is 3.6 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.13 sec in the 15-150 keV band
is 5.2 +- 0.3 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/306778/BA/

If we receive any more data on this burst and it shows any on-going
activity beyond the current data limit of T+88 sec, then we will
issue a revised circular.

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 080319C (Swift-BAT trigger #306778: Pagani et al., GCN
7442
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 , Stamatikos et al., GCN 7483
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 )
triggered Konus-Wind at T0=44757.938 s UT (12:25:57.938).

The burst light curve shows a multipeaked structure
with a total duration of ~15 s.

As observed by Konus-Wind the burst
had a fluence of 1.50(-0.21, +0.34)x10^-5 erg/cm2,
and a 256-ms peak flux measured from T0+0.256 s
of 3.35(-0.70, +0.79)x10^-6 erg/cm2/s
(both in the 20 keV - 4 MeV energy range).

The time-integrated spectrum of the burst
(from T0 to T0+16.640 s) is well fitted (in the 20 keV-4 MeV range)
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.20 +/- 0.10,
and Ep = 594(-131, +224) keV (chi2 = 79.3/73 dof).
Fitting by GRBM (Band) model yields:
the low-energy photon index is alpha = -1.01 +/- 0.13,
the high energy photon index beta = -1.87(-0.63, +0.15),
the peak energy Ep = 307(-92, +141) keV (chi2 = 76.1/72 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/GRB080319_T44757/

S. T. Holland (CRESST/USRA/GSFC) & C. Pagani (PSU) report on behalf of
the Swift/UVOT team:

   The Swift/UVOT observed the field of GRB 080319C starting 210 s
after the BAT trigger (Pagani et al., GCN Circ. 7442
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 ).  We detect the
optical afterglow in the v, b, u, and white filters at location of the
KAIT optical afterglow (Li, et al., 2008, GCNC 7441).  The UVOT source
position is

RA(J2000.0) =  17:15:55.49
Dec(J2000.0) = +55:23:30.6

with an estimated uncertainty of +/-0.53 arcsec (radius, 90%
confidence).

   Magnitudes and upper limits are reported below.

Filter    T_start (s) T_stop  Exposure      Mag  Err  Comment
v          334        353       19     18.09 0.30
b          433        443       10     19.02 0.53
u          408        581       39     19.08 0.36
uvw1        383       2410      214    >20.0        3-sigma UL
uvm2        358       2385      175    >19.6        3-sigma UL
uvw2        463       2336      175    >19.9        3-sigma UL
white        227        327       98     18.81 0.08

The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0 .03 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 three ultraviolet filters may indicate that the redshift is
z >~ 3.

K.Onda, M. Tashiro, Y. Terada, Y. Urata, A. Endo,
M. Suzuki, N. Kodaka, K. Morigami (Saitama U.),
M. Ohno, T. Uehara, T. Takahashi, Y. Fukazawa,
C. Kira, Y. Hanabata (Hiroshima U.), T. Tamagawa (RIKEN),
K. Yamaoka, Y. E. Nakagawa, S. Sugita (Aoyama Gakuin U.),
T. Enoto, R. Miyawaki, K. Nakazawa, K. Makishima (Univ. of Tokyo),
E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara (Univ. of Miyazaki),
M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), S. Hong (Nihon U.),
on behalf of the Suzaku WAM team, report:

The long GRB 080319C (Swift/BAT trigger #306778 ; Pagani et al.,
GCN 7442
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 ) triggered the Suzaku Wide-band  All-sky Monitor (WAM)
which covers an energy range of 50 keV - 5 MeV at 12:25:56 UT (=T0).
The observed light curve shows a multi-peaked structure starting at T0s,
ending at T0+14s with a duration (T90) of about 13 seconds.
The fluence in 100 - 1000 keV was 6.4(+0.4, -0.9)*10^-6 erg/cm^2.
The 1-s peak flux measured from T0+2s was 4.2(+0.2, -0.3) photons/cm^2/s
in the same energy range.

Preliminary result shows that the time-averaged spectrum from
T0s to T0+13s is well fitted by a power-law with exponential cutoff model:
   dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
   alpha       0.67(+0.30, -0.36), and
   Epeak       761(+255, -136) keV (chi^2/d.o.f. = 32.2/23).

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

K. Wiersema, N. Tanvir (University of Leicester), P. Vreeswijk, J. Fynbo 
(DARK Cosmology Centre), R. Starling, E. Rol (Leicester) and P. Jakobsson 
(Hertfordshire) report on behalf of a large collaboration:

We observed the afterglow of GRB 080319C (GCN 7442
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 ) with Gemini North, 
using the GMOS-N instrument. We took spectra using the B600 grism 
(exposure time 4 x 900s) in bad weather conditions: exposures were taken 
through holes in the cloud deck. Observations started at 14:51 UT on
March 19th.

The spectrum shows several absorption lines of C IV, Al II, Si II, Al III, 
Mg I and the CrII / ZnII blend. From these we find the redshift z = 1.95.

We are very grateful to the Gemini staff, in particular Paul Hirst, for 
executing these observations.