GRB 080319D

P. J. Brown (PSU), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
M. M. Chester (PSU), N. Gehrels (NASA/GSFC), O. Godet (U Leicester),
S. T. Holland (CRESST/USRA/GSFC), S. Immler (CRESST/GSFC/UMD),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
P. T. O'Brien (U Leicester), J. P. Osborne (U Leicester),
C. Pagani (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL),
M. Perri (ASDC), J. L. Racusin (PSU), M. Stamatikos (NASA/ORAU),
R. L. C. Starling (U Leicester), E. Troja (U Leicester/INAF-IASFPA)
and T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:

At 17:05:09 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080319D (trigger=306793).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 99.480, +23.933 which is 
   RA(J2000) = 06h 37m 55s
   Dec(J2000) = +23d 56' 01"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is usual with an image trigger, the prompt light 
curve does not not show any clear structure.  We will be able to tell more with 
the full data set. 

The XRT began observing the field at 17:07:36.9 UT, 147.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued, 
variable X-ray source with an enhanced position: RA, Dec 99.47270, 23.94306
which is equivalent to:
   RA(J2000)  = 06h 37m 53.45s
   Dec(J2000) = +23d 56' 35.5"
with an uncertainty of 3.0 arcseconds (radius, 90% containment). This
location is 44 arcseconds from the BAT onboard position, within the BAT
error circle. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of
2.17e+21 cm^-2 (Kalberla et al. 2005), so we cannot constrain the
redshift at this time using the relation from Grupe et al. (2007). A
summary of the promptly downlinked data is given at
http://www.swift.ac.uk/sper/306793/. 

UVOT took a finding chart exposure of 100 seconds with the White (160-650 nm)
filter starting 152 seconds after the BAT trigger. A possible afterglow 
candidate has been found in the initial data products, at a magnitude of 
~19 mag. No correction has been made for the expected extinction corresponding
to E(B-V) of 0.19. The position of the tentative UVOT source is:
   RA(J2000)  = 06h 37m 53.6s
   Dec(J2000) = +23d 56' 34.1"

Burst Advocate for this burst is P. J. Brown (pbrown 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.)

Correction to GCN 7454
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 !

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

S. Immler (CRESST/GSFC/UMD) and P. J. Brown (PSU) report on behalf
of the Swift UVOT team:

The Swift/UVOT observations of the field of GRB 080319D (trigger 306793)
starting 151 seconds after the BAT trigger (Brown, et al., GCN Circ. 7453
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 )
reveal a fading optical afterglow candidate. The white and v-filter 
magnitudes
are as follows:

Filter        T_start (s)    T_stop (s)        Exp (s)    Mag (3-sigma UL)
----------------------------------------------------------------------------------------------
White    151        251            100        19.7+/-0.3
White    866        966            100        20.2+/-0.4
v        257        657            400        >19.5
v        972        1362        400        >19.5
----------------------------------------------------------------------------------------------

No correction has been made for the expected Galactic extinction 
corresponding
to E(B-V) of 0.19 (Schlegel, et al. 1998). The position of the optical 
afterglow
candidate is

RA (2000) = 06h 37m 53.6s
Dec (2000) = +23d 56' 34.2"

with an uncertainty of 0.5 arcsec, which is 2.2 arcsec offset from the XRT
position (Brown, et al., GCN Circ. 7453
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 ).

Dirk Grupe and Peter Brown (PSU)  report on behalf of the Swift-XRT team:

The Swift-XRT started observing GRB 080319D (trigger=306793, Brown et 
al. GCN
7453
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 ) at 17:07:37 UT, 148 seconds after the BAT trigger.

The astrometrically corrected X-ray position (using the XRT-UVOT 
alignment and
matching UVOT field sources to the USNO-B1 catalogue) is: RA, Dec = 
99.47254,
+23.94275 which is equivalent to:

RA (J2000):  06 37 53.41
Dec (J2000): +23 56 33.9

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

The 0.3-10 keV X-ray light curve starts with three flares up to 20 
counts/s. The
afterglow decays very fast and started to flatten at about 1000 s after the
burst. The light curves shows another break at about 5 ks after the 
burst and is
currently decaying with a decay slope of 1.3.

The spectrum of the PC data can be well fit by an absorbed single
powerlaw with photon  index 2.12 � 0.27 and column density of
 (3.8 � 1.4)e21 cm-2.  This is in excess of
the Galactic column density of 2.17e21 cm-2 in this direction.
Using this spectrum we estimated a count rate to flux conversion of
1 count/s converts to 6.28e-11 ergs/cm2/s.

If the underlying powerlaw decay continues as is, we predict an XRT 
count rate
of 1.6e-3 counts/s at T+24 hours and 6.5e-4 counts/s at T+48 hours
after the burst, or 1.0e-13 ergs/s/cm2 and 4.1e-14 ergs/s/cm2, 
respectively.

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

T. Ukwatta (GWU) S. D. Barthelmy (GSFC), P. J. Brown (PSU),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD),
D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC),
G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
(i.e. 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 080319D (trigger #306793)
(Brown, et al., GCN Circ. 7453
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 ).  The BAT ground-calculated position is
RA, Dec = 99.479, 23.982 deg which is 
   RA(J2000)  =  06h 37m 55.0s 
   Dec(J2000) = +23d 58' 56.0" 
with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 59%.
 
The mask-weighted light curve shows a roughly symmetric peak starting
at ~T+0, peaking at ~T+23, and ending at ~T+50 sec.
T90 (15-350 keV) is 24 +- 4 sec (estimated error including systematics).
 
The time-averaged spectrum from T+5.0 to T+34.5 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.92 +- 0.35.  The fluence in the 15-150 keV band is 3.2 +- 0.7 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+25.35 sec in the 15-150 keV band
is 0.1 +- 0.1 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/306793/BA/

G. Greco (Bologna University), F. Terra (Second University of
Roma "Tor Vergata"), C. Bartolini, A. Guarnieri, A. Piccioni
(Bologna University), F. Munz, G. Pizzichini (INAF/IASF Bologna),
D. Nanni (INAF/OAR and Second University of Rome "Tor Vergata"),
A. Shearer (Centre for Astronomy, Galway), 
R. Gualandi (Bologna Observatory) report:


We observed the field of GRB 080319D (Brown et al., GCN 7453
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with the 152 cm telescope located in Loiano, under unfavourable
conditions due to full moon light.

One Rc-band observation (1x600 sec) was done on 2008
March at 20.779 UT middle exposure time.

We do not detect any object at the position of the candidate
afterglow reported by Immler et al. (GCN 7458
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 ).
Our 3-sigma limiting magnitude is R~20 (based on the Nomad1 catalogue).

The image has been posted in our public directory
from where it can be retrieved
by sftp using
hostname: ermione.bo.astro.it
username: publicGRB
password: GRB_bo.
directory: GRB080319D

C. Clemens, S. Klose (Tautenburg Obs.), J. Greiner, A. Kupcu Yoldas, A. 
Yoldas, T. Kruehler and G. Szokoly (Eoetvoes Univ., Budapest and MPE 
Garching) (all others MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 080319D (SWIFT trigger 306793; P. J. Brown et 
al., GCN 7453
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 ) simultaneously in g', r', i', z', J, H and K with GROND 
(Greiner et al. 2008, PASP) mounted at the 2.2m ESO/MPI telescope at La Silla 
Observatory (Chile).

Observations started at 00:15 UT on March 20th, 2008, about 7.2 hrs after the 
GRB trigger at an airmass of 1.7 to 2.5. We obtained 0.5 hrs of total 
integration time in g', r', i' and z' and found a source, which might be the 
host galaxy, also present in the DSS2 red images at

RA (J2000.0) = 06h 37m 53.56s
DEC (J2000.0) = 23d 56' 34.2''

within the 0.5'' Swift UVOT error circle reported by S. Immler et al. in GCN 
7458
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 . The object is seen in all bands except K, implying a redshift smaller 
than 3.5.

Our co-added images reveal roughly estimated magnitudes of g' = 21.3, r' = 
20.7, i' = 19.9 and z' = 19.7, calibrated against USNO-B catalogue stars.

No statement about variability, i.e. an additional contribution from afterglow 
light, can be made at this point. Further observations are planned.

C. Clemens, S. Klose (Tautenburg Obs.), J. Greiner, A. Kupcu Yoldas, A. 
Yoldas, T. Kruehler and G. Szokoly (Eoetvoes Univ., Budapest and MPE 
Garching) (all others MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 080319D for a second time at 23:43 UT on March 
23rd, 2008, about 4.3 days after the GRB trigger with 0.5 hrs of total 
integration time in g', r', i' and z'.

We do not detect any object within the Swift UVOT error circle (S. Immler et 
al., GCN #7458
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 ) to the following 3-sigma upper limits:

g' > 24.7, r' > 23.4, i' > 22.7 and z' > 22.5.

This indicates a clear fading of the optical afterglow compared to our first 
epoch observations (C. Clemens et al., GCN #7503
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 ).